Thermal Insulation

Abstract

The present invention relates to inorganic fibres having a composition comprising: 65.7 to 70.8 wt % SiO.sub.2; 27.0 to 34.2 wt % CaO; 0.10 to 2.0 wt % MgO; and optional other components providing the balance up to 100 wt %,
wherein the sum of SiO.sub.2 and CaO is greater than or equal to 97.8 wt %; and the other components, when present, comprise no more than 0.80 wt % Al.sub.2O.sub.3; and wherein the amount of MgO and other components are configured to inhibit the formation of surface crystallite grains upon heat treatment at 1100° C. for 24 hours, wherein said surface crystallite grains comprise an average crystallite size in a range of from 0.0 to 0.90 μm.

Claims

1. Inorganic fibres having a composition comprising: 65.7 to 70.8 wt % SiO.sub.2; 27.0 to 34.2 wt % CaO; 0.10 to 2.0 wt % MgO; and optional other components providing the balance up to 100 wt %, wherein the sum of SiO.sub.2 and CaO is greater than or equal to 97.8 wt %; and the other components, when present, comprise no more than 0.80 wt % Al.sub.2O.sub.3; and wherein the amount of MgO and other components are configured to inhibit the formation of surface crystallite grains upon heat treatment at 1100° C. for 24 hours, wherein said surface crystallite grains comprise an average crystallite size in a range of from 0.0 to 0.90 μm.

2. The inorganic fibres according to claim 1, wherein the amount of MgO and other components are configured to inhibit the formation of surface crystallite grains upon heat treatment at 1100° C. for 24 hours, wherein said surface crystallite grains comprise an average crystallite size in a range of from 0.0 to 0.60 μm.

3. The inorganic fibres according to claim 1, wherein the amount of MgO and other components are configured to inhibit the formation of surface crystallite grains upon heat treatment at 1100° C. for 24 hours, wherein said surface crystallite grains comprise an average crystallite size in a range of from 0.0 to less than 0.4 μm.

4. The inorganic fibres according to claim 1, wherein the amount of MgO and other components, when present, are configured to obtain a vacuum cast preform of the fibres, which has a shrinkage of 3.5% or less when exposed to 1300° C. for 24 hrs.

5. The inorganic fibres according to claim 1, wherein the amount of MgO and other components, when present, are configured to obtain a vacuum cast preform of the fibres, which has a shrinkage of 3.5% or less when exposed to 1200° C. for 24 hrs.

6. The inorganic fibres according to claim 1, wherein the other components comprise an alkali metal oxide content in a range of from 0.0 to 0.50 wt % of the fibre composition.

7. The inorganic fibres according to claim 1, wherein the other components comprise an Al.sub.2O.sub.3 content in a range of from 0.0 to 0.70 wt % of the fibre composition.

8. The inorganic fibres according to claim 1, wherein the SiO.sub.2 content is no more than 69.2 wt % of the fibre composition.

9. The inorganic fibres according to claim 1, wherein the SiO.sub.2 content is no more than 69.0 wt % of the fibre composition.

10. The inorganic fibres according to claim 1, wherein the sum of SiO.sub.2 and CaO is greater than or equal to 98.5 wt % of the fibre composition.

11. The inorganic fibres according to claim 1, wherein the sum of SiO.sub.2 and CaO is greater than or equal to 98.8 wt % of the fibre composition.

12. The inorganic fibres according to claim 1, wherein the other components comprise no more than 1.2 wt % of the fibre composition.

13. The inorganic fibres according to claim 1, wherein the other components comprises a range of from 0.1 to 1.4 wt % of the sum of BaO+Cr.sub.2O.sub.3+Fe.sub.2O.sub.3+HfO.sub.2+La.sub.2O.sub.3+Mn.sub.3O.sub.4+Na.sub.2O+K.sub.2O+P.sub.2O.sub.5+SrO+SnO.sub.2+TiO.sub.2+V.sub.2O.sub.5+ZrO.sub.2+ZnO.

14. The inorganic fibres according to claim 1, wherein the other components comprises a range of from 0.1 to 1.2 wt % of the sum of BaO+Cr.sub.2O.sub.3+Fe.sub.2O.sub.3+HfO.sub.2+La.sub.2O.sub.3+Mn.sub.3O.sub.4+Na.sub.2O+K.sub.2O+P.sub.2O.sub.5+SrO+SnO.sub.2+TiO.sub.2+V.sub.2O.sub.5+ZrO.sub.2+ZnO.

15. The inorganic fibres according to claim 1, wherein the other components comprises a range of from 0.1 to 1.0 wt % of the sum of BaO+Cr.sub.2O.sub.3+Fe.sub.2O.sub.3+HfO.sub.2+La.sub.2O.sub.3+Mn.sub.3O.sub.4+Na.sub.2O+K.sub.2O+P.sub.2O.sub.5+SrO+SnO.sub.2+TiO.sub.2+V.sub.2O.sub.5+ZrO.sub.2+ZnO.

16. The inorganic fibres according to claim 1, wherein the other components comprises a range of from 0.1 to 0.8 wt % of the sum of BaO+Cr.sub.2O.sub.3+Fe.sub.2O.sub.3+HfO.sub.2+La.sub.2O.sub.3+Mn.sub.3O.sub.4+Na.sub.2O+K.sub.2O+P.sub.2O.sub.5+SrO+SnO.sub.2+TiO.sub.2+V.sub.2O.sub.5+ZrO.sub.2+ZnO.

17. The inorganic fibres according to claim 1, wherein the inorganic fibres are non-reactive with mullite when held in contact at 1200° C. for 24 hours.

18. An insulation or sealant system comprising: (a) a refractory component comprising a contact surface; and (b) an insulating lining or sealant material comprising inorganic fibres having a composition according to claim 1, wherein the insulating lining or sealant material is disposed against the contact surface.

19. The insulation or sealant system of claim 18, wherein the refractory component comprises mullite.

20. The insulation or sealant system according to claim 18, wherein the refractory component comprises at least 20 wt % alumina.

21. The insulation or sealant system of claim 18, wherein the refractory component comprises refractory mortar, refractory cement, refractory board, refractory fibres or refractory bricks.

22. A process for the manufacture of inorganic fibres comprising: (a) selecting a composition and proportion of each of the following raw materials: (i) silica sand and (ii) lime, said lime comprising at least 0.10 wt % magnesia; and (iii) optional additives (b) mixing the silica sand; lime; and optional additives to form a mixture; (c) melting the mixture in a furnace; (d) shaping the molten mixture into inorganic fibres, wherein the raw material selection comprises composition selection and proportion selection of silica sand and lime to obtain an inorganic fibre composition according to claim 1.

23. The process according to claim 22, wherein the raw materials consists of silica sand and lime.

24. The process according to claim 22, wherein the composition selection and proportion selection of the raw materials is configured so the amount of magnesia in the fibre composition is sufficient to inhibit the formation of surface crystallite grains upon heat treatment at 1100° C. for 24 hours, wherein said surface crystallite grains comprises an average crystallite size in a range of from 0.0 to 0.90 μm.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0142] FIG. 1 is a SEM image of a fibre from sample 24

[0143] FIG. 2 is a SEM image of a fibre of the prior art (sample 23)

[0144] FIGS. 3a & 3b are SEM images of a fibre from sample 19

[0145] FIG. 3c is a SEM image of a fibre from sample 31

[0146] FIG. 3d is a SEM image of a fibre from sample 29

[0147] FIG. 4a is a SEM image of a fibre from sample 22

[0148] FIG. 4b is a SEM image of a fibre from sample 20

[0149] FIG. 4c is a SEM image of a fibre from sample 4

[0150] FIG. 4d is a SEM image of a fibre from sample 36

[0151] FIG. 5a is a SEM image of a fibre from sample 8

[0152] FIG. 5b is a SEM image of sample 26

[0153] FIG. 6 is a schematic diagram of bake furnace sealant system

[0154] FIG. 7 is a schematic diagram of a furnace lined with inorganic fibres of the present disclosure.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0155] Fibres according to the disclosure and comparative fibres described herein have been produced at either the French production facilities in Saint Marcellin, France by spinning [made from the melt by forming a molten stream and converting the stream into fibre by permitting the stream to contact one or more spinning wheels]; or at the applicant's research facilities in Bromborough, England by spinning or alternatively by blowing [fibres made from the melt by forming a molten stream and converting the stream into fibre by using an air blast directed at the stream]. The disclosure is not limited to any particular method of forming the fibres from a melt, and other methods [e.g. rotary or centrifugal formation of fibres; drawing; air jet attenuation] may be used. The resultant fibres were then fed onto a conveyor belt and entangled by needling methods, as known in the art.

[0156] The raw materials used to produce the inorganic fibres of a preferred embodiment of the present disclosure are lime and silica sand. The chemical analysis (normalised) of the lime used is provided in Table 1 below. The incidental impurities (100-CaO—SiO.sub.2) in the lime is typically less than 2.0 wt %. The silica sand purity may be 98.5 wt % or 99.0 wt % or higher. Typically, the silica sand had a purity of greater than 99.5 wt % silica and less than 200 ppm Fe.sub.2O.sub.3; less than 1000 ppm Al.sub.2O.sub.3; less than 200 ppm TiO.sub.2, less than 100 ppm CaO and less than 100 ppm K.sub.2O.

[0157] Some of the compositions produced had elevated K.sub.2O levels due to the additional of fluxing agents in the pilot scale furnace in Bromborough or due to cross-contamination from previous production in the Saint Marcellin furnace. Amongst others, samples P61-0481 and P61-0488 are representative of compositions produced from the raw materials of silica sand and lime only.

TABLE-US-00001 TABLE 1 Un-normalised Lime bag CaO Al.sub.2O.sub.3 Fe.sub.2O.sub.3 K.sub.2O MgO SiO.sub.2 ZrO.sub.2 XRF total B1 97.97 0.28 0.21 0.04 0.41 1.09 0.01 98.39 B2 98.12 0.30 0.21 0.04 0.38 0.93 0.00 99.17 B3 97.79 0.30 0.21 0.04 0.37 1.26 0.02 99.39 B4 97.56 0.35 0.21 0.04 0.38 1.43 0.01 99.00 B5 97.64 0.54 0.21 0.04 0.38 1.15 0.01 99.94 B6 97.61 0.49 0.22 0.04 0.41 1.15 0.04 99.92 B7 97.97 0.33 0.20 0.04 0.40 1.01 0.01 98.93 B8 95.15 0.34 0.20 0.04 0.40 3.85 0.00 99.94

[0158] The fibres/blankets made therefrom were then evaluated using the test methodology as described:

[0159] Test Methodology

[0160] The EN 1094-1-2008 standard was used for the shrinkage, tensile strength and resiliency tests.

[0161] Shot Content

[0162] Shot content was determined by a jet sieve method as detailed in WO2017/121770, incorporated herein by reference.

[0163] Thermal Stability (Shrinkage)

[0164] The method for determination of dimensional stability of refractory materials, including the refractory glass fibre insulation materials, is based on the EN ISO 10635. This method is a shrinkage test that measures the change of a flat specimen's linear dimensions after a heat treatment.

[0165] The shrinkage test requires a relatively rigid specimen's so that the linear dimensions could be accurately determined before and after the heat treatment. In cases where a needled fibre blanket specimen were not available, starch bonded vacuum formed boards were prepared from the glass fibre samples.

[0166] To prepare the vacuum formed boards, the as made fibre material were chopped using a small-scale industrial granulator through a #6 mesh (.sup.˜3 mm opening). Chopped fibre samples were lightly cleaned using a sieve to remove any debris and large glass residues. 40 g of chopped clean fibre was mixed in 500 ml of 5 wt % concentration potato starch in water solution to create a slurry. Subsequently a vacuum former was used to produce 75×75 mm boards with a thickness of 10-15 mm. The vacuum former consists of a sealed acrylic mould with a 100 μm mesh bottom, a vacuum pump was used to remove the water from the slurry while manually compressing the shape using a flat plate. Vacuum formed boards were dried at 120° C.

[0167] To measure permanent linear shrinkage, the linear dimensions of specimen were measured to an accuracy of ±5 μm using a travelling microscope. The specimens were subsequently placed in a furnace and ramped to a temperature 50° C. below the test temperature (e.g. 1300° C.) at a rate of 300° C./hour and then ramped at 120° C./hour for the last 50° C. to test temperature and held for 24 hours. Specimens were allowed to cool down naturally to room temperature at the end of this heat treatment. After heat treatment, the specimen's linear dimensions were measured again using the same apparatus to calculate the change in dimensions. Shrinkage values are given as an average of 4 measurements.

[0168] Reactivity with Mullite

[0169] Needled fibre blanket specimens with approximate dimensions of 50 mm×100 mm were used for this test. Blanket specimens were placed on a fresh mullite Insulating Fire Brick (JM 28 IFB). The specimen, along with the IFB substrate, was heated treated at 1200° C. for 24 hours to confirm the reactivity after the heat treatment. The specimen and IFB were inspected for any sign of melting or reaction. The sample which did not react with the IFB at all were evaluated as good (◯). The sample which reacted with the IFB (the sample was adhered to IFB or sign of melting was observed) were evaluated as poor (X).

[0170] Bio-Solubility

[0171] The biological solubility of fibrous materials can be estimated in a system in which the material is exposed to a simulated body fluid in a flow-through apparatus (i.e., in vitro). This measurement of solubility is defined as the rate of decrease of mass per unit surface area (Kdis). Although several attempts have been made to standardize this measurement, there is currently no international standard. Major protocol differences among laboratories include different simulated body fluid chemistries (and, most significantly, different buffering and organic components), flow rates, mass and/or surface area of samples, determination methods for specific surface area, and determination of mass loss. Consequently, Kdis values should be regarded as relative estimates of chemical reactivity with the simulated body fluid under the specific parameters of the test, not as measures of absolute solubility of fibrous particles in the human lung. The flow through solubility test method used in this study is a 3-week long solubility test in pH 7.4 saline. Two channels of each unique specimen are simultaneously tested. Samples of saline solution flowing over the fibre specimens are taken after 1, 4, 7, 11, 14, 19 and 21 days. The saline samples are analysed using the ICP method to measure the oxide dissolution levels in ppm level. To validate the flow test results and calculate the final dissolution rates for each specimen, the square root of remaining fibre mass against sampling times are plotted. Deviation from a linear trend could suggest an issue with the results. A good linear regression fit was observed in the flow test results conducted in this study. Based on the historical data collected by authors, a minimum of 150 ng/cm.sup.2 hr dissolution rate is typically required for a fibre to have exoneration potential. In the static solubility test method, fibre specimens are agitated in saline solution at 37° C. to replicate conditions within the lungs. The test monitors fibre dissolution after 24 hours using the ICP method. SiO.sub.2 and CaO typically make up the majority of the dissolution material.

[0172] Resiliency

[0173] The resiliency test (EN1094-1-2008) demonstrates the ability of fibre insulation products to spring back after being compressed to 50% of their initial thickness. Samples for resiliency testing in this document were in needled blanket form. As made or heat treated blanket specimens were cut to 100 mm×100 mm squares and dried at 110° C.±5° C. for 12 hours to remove any absorbed moisture. Specimens were subsequently allowed to cool to room temperature and then test immediately. The initial thickness of blanket specimens were measured using the pin and disk method prior to resiliency testing. An Instron universal mechanical test frame, equipped with 150 mm diameter flat compression platens was used for the resiliency tests. During the test, the specimens were compressed to 50% of their original thickness at a rate of 2 mm/min, the specimens were then held under compression for 5 minutes. Subsequently the specimens were allowed to spring back by lifting the compression platen until 725 Pa (for specimens >96 kg/m.sup.3 bulk density) or 350 Pa (for specimens <96 kg/m.sup.3 bulk density) was registered on the load cell and then held for a further 5 minutes. Following this test, the resiliency values were calculated using the formula below:

[00001]$R=\frac{d_f}{d_0}\times 100$

[0174] R=Resiliency

[0175] d.sub.f=Thickness after testing

[0176] d.sub.0=Initial Thickness

[0177] Tensile Strength

[0178] The parting strength of a blanket is determined by causing rupture of test pieces at room temperature. Samples are cut using a template (230±5 mm×75±2 mm). The samples are dried at 110° C. to a constant mass, cooled to room temperature and then measured and tested immediately.

[0179] The width is measured using a steel rule to a 1 mm accuracy across the middle of the piece and the thickness of the sample is measured on each sample (at both ends of the sample) using the EN1094-1 needle method. A minimum of 4 samples for each test are taken along the direction of manufacture.

[0180] The samples are clamped at each end by clamps comprising a pair of jaws having at least 40 mm×75 mm in clamping area with serrated clamping surfaces to prevent slippage during the test. These dimensions give an unclamped span of 150±5 mm to be tested. The clamps are closed to 50% of the sample thickness (measured using a Vernier caliper or ruler).

[0181] The clamps are mounted in a tensile testing machine [e.g. Instron 5582, 3365 using a 1 kN load cell, or a machine of at least the equivalent functionality for testing tensile strength]. The crosshead speed of the tensile testing machine is a constant 100 mm/min throughout the test. Any measurement with the sample breaking nearer to the clamp jaw than to the centre of the sample is rejected.

[0182] The maximum load during the test is recorded to allow strength to be calculated.

[0183] Tensile strength is given by the formula:

[00002]$R\left(m\right)=\frac{F}{W\times t}$

[0184] Where: [0185] R(m)=Tensile Strength (kPa) [0186] F=Maximum Parting Force (N) [0187] W=Initial Width of the active part of the test piece (mm) [0188] T=Initial Thickness of test piece (mm)

[0189] The test result is expressed as the mean of these tensile strength measurements together with the bulk density of the product.

[0190] Fibre Diameter

[0191] Fibre diameter measurements were carried out using the Scanning Electron Microscope (SEM). SEM is a micro-analytical technique used to conduct high magnification observation of materials' microscopic details. SEM uses a tungsten filament to generate an electron beam, the electron beam is then rastered over a selected area of the specimen and the signal produced by the specimen is recorded by a detector and processed into an image display on a computer. A variety of detectors can be used to record the signal produced by the sample including secondary electrons and backscattered electrons detectors.

[0192] The particular SEM equipment used operates under vacuum and on electrically conductive specimens. Therefore, all glass/ceramic fibre specimens need to be coated with gold or carbon prior to SEM analysis. Coating was applied using an automated sputter coater at approximately 20 nm. In order to prepare the fibrous specimens for diameter measurements, fibre specimens were crushed using a pneumatic press at 400 psi. The aim of crushing is to ensure the sample is crushed enough to be dispersed without compromising the fibre length, crushing results in fibres with aspect ratios >3:1. The crushed fibre specimens is then cone and quartered to ensure representative sampling. Crushed and quartered fibres are dispersed in IPA. Typically, 50 μg of fibres are placed in a 50 mL centrifuge tube and 25 mL IPA is added. A SEM stub is then placed at centre of a petri dish, then the centrifuge tube is vigorously shaken and emptied into the petri dish containing the SEM stub. The petri dish is left in fume cupboard for 1 hour for the fibres to settle on the SEM stub. The SEM stub is then carefully coated with gold in preparation for SEM imaging.

[0193] Following this sample preparation step, an automated software on the SEM equipment is utilised to collect 350 unique secondary electron images at 1500× magnification from the SEM stub. Following the image collection step, the images are processed by the Scandium® system available from Olympus Soft Imaging Solutions GmbH, to measure the diameter of fibres. The process involves manual inspection of measured fibres in every image to ensure only the fibres particles with aspect ratios greater than 3:1 are measured. The final fibre diameter distribution is reposted in a graph as well as numerical average/arithmetic mean diameter.

[0194] Crystallite Grain Size

[0195] Crystallite grain size measurements on heat treated fibre materials were carried out using the Scanning Electron Microscope (SEM). SEM is a micro-analytical technique used to conduct high magnification observation of materials' microscopic details. SEM uses a tungsten filament to generate an electron beam, the electron beam is then rastered over a selected area of the specimen and the signal produced by the specimen is recorded by a detector and processed into an image display on a computer. A variety of detectors can be used to record the signal produced by the sample including secondary electrons and backscattered electrons detectors.

[0196] The particular SEM equipment used operates under vacuum and on electrically conductive specimens. Therefore, all glass/ceramic fibre specimens need to be coated with gold or carbon prior to SEM analysis. Coating was applied using a automated sputter coater at approximately 20 nm. In order to prepare the fibrous specimens for grain size measurements, fibre specimens were cone and quartered to ensure representative sampling. A SEM stub is prepared with a small representative sample of the specimen and carefully coated with gold in preparation for SEM imaging.

[0197] Following this sample preparation step, the SEM equipment is utilised to collect several unique secondary electron images at suitable magnification based on morphology (typically in 5000-10000× magnification range) from the SEM stub. Following the image collection step, the images are processed by a computer software program (Olympus Scandium®) to measure the grain size by drawing circles around the visible grain boundaries in several SEM images. The process involves manual inspection of fibres in every image to ensure only the fibres are in focus. The final grain size is reported as numerical average of all measurements (preferably a minimum of 10 measurements of representative crystals). Preferably, the crystallite size is determined from a random selection of at least five fibres, with measurements of representative crystallite sizes of 5 grains taken from each fibre. Fibre measurements falling more than 2 standard deviations from the mean are to be disregarded. Due to limitations in magnification and resolution of SEM images, the minimum measurable grain size was about 0.4 μm. Samples with lower crystallite grain sizes were reported as having a mean grain size value <0.4 μm.

[0198] Crystalline grains are differentiated from other surface imperfections by their regularity in frequency and shape, which is characterized by the crystallites protruding from the surface of the fibre, as indicated in the increase grain sizes from FIG. 4a to FIG. 4d. Surface imperfections include irregular shaped platelet formations as illustrated on FIGS. 3b and 3d.

[0199] Melting Temperature

[0200] The melting temperature of the fibres was determined by DSC (10 k/min temperature increase from 30° C. to 1500° C.). Sample 26b (50 mg of fine powder ground from fibre) had a melting temperature of 1435.3° C.

[0201] Fibre Composition

[0202] Fibre composition was determined using standard XRF methodology. Results were normalised after analysis performed on SiO.sub.2, CaO, K.sub.2O, Al.sub.2O.sub.3, MgO and oxide components listed in Table 6. Un-normalised results were discarded if the total weight of the composition fell outside the range 98.0 wt % to 102.0 wt %.

[0203] Effects of Impurities

[0204] To assess the effects of the incidental impurities in the raw materials, an ultra pure sample (C-24) was produced using a silica (SiO2: 99.951 wt %, Al.sub.2O.sub.3: 0.038 wt % Fe.sub.2O.sub.3: 0.012 wt %) and calcia (CaO: 99.935 wt %, SiO.sub.2: 0.011 wt %, Al.sub.2O.sub.3: 0.012 wt % Fe.sub.2O.sub.3: 0.011 wt %, SrO: 0.031 wt %). The remaining components were less than the XRF detection limit (<0.01 wt %).

[0205] To assess the effect of impurities, additional amounts of Al.sub.2O.sub.3, MgO, TiO.sub.2 and ZrO.sub.2 were added to the existing incidental impurities. With reference to Table 4a, increasing amounts of MgO, TiO.sub.2 and Al.sub.2O.sub.3 results in reduced thermal stability at 1300° C. (24 hrs), as measured by the % shrinkage. Example 34 is a near repetition of sample E-174 from U.S. Pat. No. 5,332,699.

TABLE-US-00002 TABLE 2 CaO + Sample SiO.sub.2 CaO Al.sub.2O.sub.3 K.sub.2O MgO SiO.sub.2 C-1 72.8 24.9 1.1 0.6 0.6 97.7 C-2 71.2 28.1 0.33 0.06 0.17 99.3 1 70.7 28.8 0.26 0.03 0.13 99.5 2 70.6 28.9 0.28 0.04 0.16 99.5 3 70.6 28.5 0.55 0.12 0.19 99.1 4 70.5 28.4 0.69 0.18 0.23 98.9 5 70.3 29.1 0.36 0.05 0.17 99.4 6 69.5 30.0 0.27 0.04 0.15 99.5 7 69.4 30.1 0.32 0.03 0.15 99.5 8 67.7 31.9 0.25 0.03 0.15 99.6 9 67.1 32.4 0.28 0.02 0.15 99.5 10 66.0 33.1 0.60 0.04 0.18 99.1 11 65.7 33.8 0.22 0.03 0.15 99.5 12 65.6 34.0 0.27 0.02 0.15 99.6 13 65.3 34.2 0.23 0.03 0.16 99.5 14 65.0 34.5 0.35 0.02 0.17 99.5 15 64.5 35.1 0.19 0.06 0.16 99.6 16 63.3 36.1 0.22 0.10 0.29 99.4 17 62.8 36.7 0.23 0.07 0.16 99.5 18 61.5 38.0 0.21 0.09 0.16 99.5 19 67.2 32.3 0.07 0.02 0.23 99.5 20 69.0 30.2 0.49 0.03 0.23 99.2 21 66.0 33.5 0.18 0.02 0.32 99.5 22 66.3 33.2 0.19 0.01 0.26 99.5 C-23 66.3 33.2 — 0.004 0.03 99.5 C-24 65.8 34.2 0.02 0.0 0.0 100.0 25 63.3 36.1 0.22 0.10 0.29 99.4 26 68.0 31.3 0.18 0.27 0.21 99.3 26b 67.1 32.4 0.23 0.10 0.15 99.5 P61-0488 66.2 33.3 0.15 0.01 0.26 99.5 P61-0481 65.9 33.5 0.15 0.01 0.39 99.4 C-3 60.7 38.9 0.26 0.07 0.17 99.6 C-4 64.9 29.8 0.15 0.01 5.2 94.7 C-5 60.7 38.8 0.23 0.12 0.17 99.5

[0206] Results

[0207] Referring to Table 2 & 3, there is shown the composition of inorganic fibres as % weight of the total composition according to Examples 1 to 26b, P61-0481, P61-0488 and Comparative Examples C1 to C5; C-27, C-34-C-36. As illustrated in Table 3, inorganic fibre compositions with silica levels less than 65.7 wt % were found to be not compatible with mullite based bricks, adhering to the bricks after being in contact at 1200° C. for 24 hrs. Inorganic fibre compositions with higher silica levels had generally higher shot content and higher fibre diameter. The results from sample P50 indicates that ZrO.sub.2 may be able to partially substitute SiO.sub.2 in the glassy forming network, with these samples also being compatible with mullite based bricks despite the low SiO.sub.2 content of the samples. The incorporation of a small portion (e.g. up to 2.0 wt % or up to 1.5 wt %) ZrO.sub.2 within the glassy network is likely to maintain the non-reactive nature of the composition to mullite based bricks or other alumina based compositions.

TABLE-US-00003 TABLE 3 Mullite Shrinkage at Shot Mean Fibre Reactivity @ 1300° C. content diameter Sample 1200° C. (24 hrs) % wt (μm) C-1 ◯ 2.0 — 6.9 C-2 ◯ 1.4 59.3 — 1 — 0.9 51.9 5.7 2 ◯ 1.4 52.0 — 3 ◯ 2.2 54.5 — 4 ◯ 2.7 53.4 2.67 5 ◯ 1.1 50.6 — 6 ◯ — 49.5 — 7 ◯ 1.2 47.8 — 8 ◯ 2.0 34.6 — 9 ◯ 1.4 47.3 — 10 ◯ 1.2 36.6 3.02 11 ◯ 0.8 37.7 — 12 X 1.3 37.4 3.33 13 X 2.0 39.7 — 14 X — 38.2 2.87 15 — 2.2 — — 16 — 1.7 — — 17 — 2.6 — — 18 — 3.3 — — 19 — 2.1 — — 20 — 1.7 — — 21 — 1.6 — 2.65 22 — 1.1 — 2.37 25 — 1.7 — — 26 — 2.0 — — P50 ◯ 5.3 — — C-3 — 8.6 — — C-4 X 14.5 — — C-5 — 5.6 — —

[0208] Shrinkage @ 1300° C. for 24 Hours

[0209] The lowest shrinkage (best high temperature performance) was observed in samples 32 & 33. Sample 33 was a control sample with no additives, whereas Sample 32 has a slightly elevated MgO level, although in both samples, the sum of SiO.sub.2 and CaO is greater than 99.0 wt %. Sample 32 appears to be an anomaly in the correlation between shrinkage and MgO content of Samples 30 to 33. Likewise, Example 37 is also considered a suspect result, with the shrinkage result expected to be below 4%. The results indicate that, in general, a higher CaO+SiO.sub.2 level corresponds to fibre compositions with improved high temperature stability as measured by the shrinkage test.

[0210] Surface Crystallite Size

[0211] The ultra-pure raw materials were difficult to form fibres and when fibres were formed, yield was low and fibre diameter was large (e.g. >500 μm). As illustrated in FIG. 1, The surface of the fibres contain a mean crystallite grain size approaching 5 μm, with cracking also observed. The prevalence of surface crystallites was also noted on the high purity sample of the prior art (FIG. 2; Sample C-23), with a mean crystallite grain size of about 1 μm.

TABLE-US-00004 TABLE 4a Static Solubility CaO + (pH 7.4 Shrinkage # SiO.sub.2 CaO Al.sub.2O.sub.3 K.sub.2O MgO ZrO.sub.2 TiO.sub.2 SiO.sub.2 ppm) at 1300° C. C-27 59.9 35.2 0.34 0.10 4.31 0.00 — 95.1 380 24.1 28 62.4 35.4 0.24 0.13 1.66 0.00 — 97.8 265 6.1 29 62.6 35.7 0.23 0.06 1.35 0.00 — 98.3 375 11.3 30 65.7 33.1 0.19 0.09 0.97 0.00 — 98.8 294 7.0 31 65.4 33.4 0.20 0.08 0.82 0.00 — 98.8 270 3.4 32 66.1 33.0 0.19 0.10 0.56 0.00 — 99.1 289 1.7 33 66.1 33.4 0.18 0.05 0.25 0.00 — 99.5 548 2.6 C-34 63.4 34.9 0.84 0.08 0.47 0.32 — 98.3 301 5.7 C-35 65.5 32.6 1.48 0.13 0.21 0.00 — 98.1 167 6.6 C-36 65.5 33.1 1.04 0.18 0.20 0.00 — 98.6 208 4.1 37 65.5 33.6 0.56 0.14 0.26 0.00 — 99.1 249 5.0 P40 66.0 31.8 0.45 0.04 0.79 0.71 0.03 97.8 140 4.0 P41 66.4 31.8 0.17 0.04 0.89 0.03 0.66 98.2 235 5.5 P47 67.2 31.8 0.17 0.41 0.24 0.03 0.02 99.0 259 1.9 C-P50 63.5 28.6 0.17 0.31 0.23 7.2 0.03 92.1 50 5.3

[0212] As indicated in Table 4a, higher totals of CaO+SiO.sub.2 tend to correspond to higher high temperature performance and bio-solubility. Table 4b further discloses the correlation between high temperature performance and the MgO content, with lower MgO contents correlating with lower shrinkage of the fibres at 1300° C.

[0213] Static Solubility

[0214] As indicated in Table 4a, increasing amounts of ZrO.sub.2 (see samples C-32, P40 and C-P50) results in a reduction in bio-solubility of the fibres.

TABLE-US-00005 TABLE 4b CaO + Shrinkage # SiO.sub.2 CaO Al.sub.2O.sub.3 K.sub.2O MgO ZrO.sub.2 SiO.sub.2 at 1300° C. 38 65.36 33.72 0.17 0.02 0.76 0.00 99.09 3.8 39 65.20 34.05 0.16 0.01 0.58 0.00 99.25 2.7 40 65.23 34.12 0.15 0.01 0.51 0.00 99.35 2.2 41 65.50 33.65 0.16 0.01 0.66 0.00 99.15 3.2 42 65.44 33.77 0.14 0.01 0.58 0.01 99.21 2.9 43 65.43 33.88 0.14 0.01 0.52 0.01 99.31 2.2 44 65.46 33.87 0.15 0.01 0.47 0.01 99.33 3.1 45 65.56 33.75 0.24 0.02 0.41 0.02 99.31 2.2 46 65.51 33.90 0.14 0.01 0.37 0.01 99.41 2.1 47 65.72 33.68 0.18 0.01 0.36 0.01 99.40 1.8 48 65.87 33.59 0.17 0.02 0.32 0.01 99.45 1.8 49 65.93 33.48 0.15 0.01 0.39 0.01 99.41 1.9 50 65.98 33.46 0.18 0.02 0.32 0.01 99.43 1.6 51 66.16 33.36 0.15 0.01 0.29 0.01 99.52 1.4 52 66.33 33.25 0.14 0.01 0.27 0.01 99.58 1.2 53 66.25 33.30 0.15 0.01 0.26 0.01 99.55 1.4 54 65.56 33.84 0.14 0.01 0.41 0.01 99.40 1.3 55 66.26 33.22 0.19 0.01 0.26 0.01 99.48 1.1

[0215] The effect of the additional of MgO is illustrated in FIGS. 3a to 3d, with sample 19 (FIGS. 3a & 3b) and sample 31 (FIG. 4) representing a composition with MgO being the predominant minor oxide component. FIG. 3b & 3d also illustrate examples of surface imperfections, including surface platelets, which are distinct from the regularity and form of the crystallites of FIG. 2. The results indicate that MgO up to at least 4.3 wt % is able to suppress crystallite growth at 1100° C., although increasing MgO levels also result in an increase in fibre shrinkage, with MgO contents in excess of 2 wt % being less suitable for continuous use applications at or above 1200° C. (Table 5). The effect of increased levels of Al.sub.2O.sub.3 are illustrated in FIGS. 4a to 4d, with a mean crystallite size of almost 1 μm obtained with an Al.sub.2O.sub.3 content of 1.04 wt % (sample 36), with CaO+SiO2 wt % of 98.6 wt %. The effect of K.sub.2O content is illustrated in FIGS. 5a (sample 8) and 5b (sample 26), with the increase in K.sub.2O content from 0.03 wt % (sample 8) to 0.27 wt % (sample 26) corresponding to a slight increase in crystallite size from below the detection limit (<0.4 μm) to 0.54 μm. Although samples P42 and P47 indicate elevated levels of K.sub.2O up to about 0.5 wt % are still able to obtain a low crystallite size (<0.4 μm) for their compositional matrix.

[0216] The addition of 0.66 wt % TiO.sub.2 and 0.89 wt % MgO (P41) resulted in poor shrinkage performance at 1300° C., with the TiO.sub.2 component appearing to contribute most to this result. P40 had a similar MgO content to P41, but with ZrO.sub.2 additional having a lower impact compared to TiO.sub.2 upon shrinkage performance at 1300° C. Whilst the effect of an additive/impurity or combinations thereof may be specific to the additive/impurity, the inorganic fibre composition may be readily configured, through testing the sensitivity of additives/impurities, to obtain the required high temperature performance in terms of shrinkage and/or grain crystallite size.

TABLE-US-00006 TABLE 5 Shrinkage at Shrinkage at Grain size % wt of 1200° C. 1300° C. (μm) @ 1100° largest minor Example (24 hrs) (24 hrs) C. (24 hrs) component 4 — 2.7 0.47 0.69 Al.sub.2O.sub.3 7 — 1.2 <0.4 0.32 Al.sub.2O.sub.3 8 — 0.8 <0.4 0.25 Al.sub.2O.sub.3 11 — 1.4 <0.4 0.22 Al.sub.2O.sub.3 19 — 2.1 <0.4 0.23 MgO 20 — 1.7 0.48 0.49 Al.sub.2O.sub.3 21 — 1.6 <0.4 0.32 Al.sub.2O.sub.3 22 — 1.1 <0.4 0.26 Al.sub.2O.sub.3 C-23 — — 0.94 0.03 MgO C-24 — — 4.93 0.02 Al.sub.2O.sub.3 25 — 1.7 0.48 0.29 MgO 26 — 2.0 0.54 0.27 K.sub.2O 27 10.6 24.1 <0.4 4.31 MgO 28 3.4 6.1 <0.4 1.66 MgO 29 4.5 11.3 <0.4 1.35 MgO 30 1.5 7.0 <0.4 0.97 MgO 31 — 3.4 <0.4 0.82 MgO 32 — 1.7 <0.4 0.56 MgO 33 — 2.6 — 0.2 MgO C-34 — 5.7 0.94 0.84 Al.sub.2O.sub.3 C-35 — 6.6 — 1.48 Al.sub.2O.sub.3 C-36 — 4.1 0.90 1.04 Al.sub.2O.sub.3 37 — 5.0 0.51 0.56 Al.sub.2O.sub.3 P40 1.4 4.0 0.53 0.79 MgO P41 1.8 5.5 0.77 0.89 MgO P47 1.1 1.9 <0.4 0.41 K.sub.2O

[0217] The results confirm that either too little or too much minor components within the composition may lead to elevated crystallite size, which is related to a deterioration in high temperature mechanical performance. In particular, MgO has been shown to inhibit crystallite growth, whilst Al.sub.2O.sub.3 has been demonstrated to promote crystallite growth. Apart from the main incidental impurities of Al.sub.2O.sub.3, MgO and K.sub.2O, the XRF analysis measured the metal oxides listed in Table 6. The maximum and minimum incidental impurity level of each of the metal oxides is provided. Typically, these minor incidental impurities are less than 0.3 wt % or less than 0.25 wt % or less than 0.20 wt %; and at least 0.10 wt %.

[0218] The person skilled in the art may readily determine the levels of specific groups or specific other components at which crystallite growth is promoted, without undue experimentation. Raw materials with varying other components (i.e. impurity) profiles may be used, when other components detrimental to crystallite growth, and hence high temperature performance, are controlled to designated levels.

[0219] As such, the inorganic fibre composition may be configured to obtain the formation of surface crystallite grains, upon heat treatment at 1100° C. for 24 hours, having an average crystallite size of 0.90 μm or less.

TABLE-US-00007 TABLE 6 Incidental impurities Max level (% wt) Min level (% wt) BaO 0.01 0.00 Cr.sub.2O.sub.3 0.02 0.00 Fe.sub.2O.sub.3 0.13 0.08 HfO.sub.2 0.00 0.00 La.sub.2O.sub.3 0.07 0.00 Mn.sub.3O.sub.4 0.00 0.00 Na.sub.2O 0.03 0.00 P.sub.2O.sub.5 0.00 0.00 SrO 0.03 0.00 TiO.sub.2 0.03 0.00 V.sub.2O.sub.5 0.01 0.00 SnO.sub.2 0.01 0.00 ZnO 0.00 0.00 ZrO.sub.2 0.03 0.00

[0220] Thermal Conductivity of Bodies of Inorganic Fibres

[0221] Thermal conductivity of a body of melt formed fibres (e.g. a blanket or other product form) is determined by a number of factors including in particular:— [0222] Diameter of the fibres; and [0223] “Shot” (unfiberised material) content

[0224] Fine diameter fibres provide low thermal conductivity to a body of fibres by reducing the scope for conduction through the solid and permitting finer inter-fibre porosity increasing the number of radiate-absorb steps for heat to pass by radiation from one side of the body to the other.

[0225] The presence of shot in a blanket increases thermal conductivity of the blanket by increasing the scope for conduction through the solid. Shot also increases the density of a blanket. All else being equal, the lower the shot content, the lower the thermal conductivity and density. For two bodies of identical fibre content and chemistry, the body with the lower shot content will have both the lower density and lower thermal conductivity.

[0226] In reference to Table 7, inorganic fibres were produced with a fibre diameter between approximately 2.6 to 3.0 μm and a shot content between 32 and 41 wt %. From the dataset provided in Tables 7 & 8, there is no clear correlation between fibre characteristics and thermal conductivity, although samples P61-0481 and P61-0488, with the lowest thermal conductivity, were obtained from a commercial production line with lower shot level and an expected greater consistency in fibre diameter of about 3 μm diameter. Blankets derived from inorganic fibres with high SiO.sub.2 content would be expected to have higher thermal conductivities due to the high shot content and fibre diameters associated with these compositions, as illustrated in Table 3. The resiliency of the inorganic fibres (Table 7) were seen to generally increase with increasing SiO.sub.2 content.

[0227] Sample P61-0488 was produced at the Saint Marcellin site using melt spinning technology at commercial scale, with production conditions optimised to reduce shot levels, which have an effect on the insulative properties of the fibre. The inorganic fibre may be formed into an entangled blanket, typically using a needling technique. Blankets are usually produced at density of at least 64 kg/m.sup.3, with standard commercial densities producible, such as 64 kg/m.sup.3, 96 kg/m.sup.3, 128 kg/m.sup.3, 160 kg/m.sup.3. The inorganic fibre may also be formed into high density modules up to 240 kg/m.sup.3. Table 9 illustrates the improvement in the insulative properties of a 128 kg/m.sup.3 blanket compared on a blanket produced from comparative example, C-1. The disclosed compositions of the present disclosure are able to form low fibre diameters and possess low shot content, contributing the excellent high temperature thermal insulative properties.

TABLE-US-00008 TABLE 7 Resiliency Resiliency Shot SEM Fibre (24 hr @ (24 hr @ (>45 μm) diameter 1150° C.) 1200° C.) SAMPLE % wt (μm) % % 8 34.6 — 69 64 10 36.6 3.02 69 66 12 32.5 2.65 68 66 13 40.6 — 68 63 14 38.3 2.70 64 60 15 38.7 2.76 — — P61-0488 32.1 3.01 — —

TABLE-US-00009 TABLE 8 Conductivity (W/m.K) (ASTM C201) Density Strength Density SAMPLE 400° C. 600° C. 800° C. 1000° C. 1100° C. 1200° C. Kg/m.sup.3 kPa Kg/m.sup.3 10 0.08 0.13 0.22 0.33 0.40 0.47 88 35 91 12 0.07 0.12 0.21 0.32 0.39 0.46 96 50 95 13 0.08 0.13 0.20 0.28 0.33 0.39 111 50 121 14 0.07 0.11 0.18 0.27 0.33 0.39 105 48 115 15 0.07 0.12 0.19 0.29 0.35 0.41 105 56 123 P61-0488 0.07 0.11 0.17 0.24 0.28 0.32 128 60 132 P61-0481 0.08 0.12 0.17 0.22 0.26 0.29 128 64 135

[0228] Heat Flow Test (ASTM C680-19 Heat Flow)

[0229] The insulation properties of 128 kg/m.sup.3 200 mm thick blankets made from the composition of samples P61-0488 and C-1 respectively, were determined. A heat source was applied to one side (hot face) of the blanket. The opposing side of the blanket was initially held at 27° C. ambient temperature, with no wind. After heating of the hot face to 1000° C., the opposing surface of the blanket (cold face) was recorded in Table 9. The results indicate the composition of the present disclosure achieves a reduction in heat loss of 15%.

TABLE-US-00010 TABLE 9 Sample Cold face temperature (° C.) Heat loss W/m.sup.2 P61-0488 73 553 C-1 80 653

[0230] Bio-Solubility

[0231] Referring now to Table 10, there is shown data for bio-solubility testing. A 21 day static and long flow through solubility test in saline pH 7.4 was conducted on the compositions shown in Table 10. Two samples of each fibre composition were simultaneously tested, with the average results reported. The saline samples were analysed using the ICP method to measure the oxide dissolution levels in ppm level. The results confirm that the fibres have low biopersistence. A low biopersistence fibre composition is taken to be a fibre composition which has a dissolution rate, in the flow solubility test, of at least 150 ng/cm.sup.2 hr or at least 170 ng/cm.sup.2 hr or at least 200 ng/cm.sup.2 hr.

[0232] The inorganic fibres under the present disclosure have comparable or improved bio-solubility in comparison with prior art fibre compositions C1 and C2. As indicated by the specific surface area measurements, fine fibre dimensions promote increased bio-solubility.

[0233] Summary of Results

[0234] The above results highlight that the fibre composition of the present disclosure is able to produce a refractory fibre with great utility without the need for the deliberate additional of significant amounts of additives to enhance one or more fibre properties. This unexpected result also enables refractory fibres to be produced with a lower carbon footprint due to the reduced number of raw materials required for its production.

TABLE-US-00011 TABLE 10 Static Flow through Solubility Dissolution Rate Specific Surface Sample (pH 7.4 saline) (pH 7.4 saline) Area Description (total ppm) (ng/cm.sup.2 hr) (m.sup.2/g) C-1 230 125 0.1652 C-2 313 379 0.2526 11 378 348 0.2887 16 295 326 0.3375 17 370 — — 18 208 — — 19 333 — — 20 292 — — 26 473 — —

[0235] Insulation or Sealant Systems

[0236] In some embodiments, the fibre of the present disclosure may be used as an insulation and/or sealant system in kilns, ovens and furnaces or other high temperature environments. The insulation or sealant system may comprise a layer of alumina rich material (e.g. mullite or refractory bricks) and a layer (e.g. blanket) of inorganic fibres. Insulation systems may be used in kilns used for: [0237] glass and ceramic goods production; [0238] chemical and petrochemical processes; [0239] iron and steel production and transformation facilities; and [0240] non ferrous metal production and transformation facilities

[0241] The fibre may also be used as insulation in heat shields and pollution devices (e.g. catalytic converters), where the non-reactivity of the fibres is beneficial.

[0242] With reference to FIG. 6, there is an illustration of a sealant system from a section of a carbon bake furnace comprising a flue wall 100 and a headwall 110. A refractory mastic comprising inorganic fibre of the present disclosure is used as a corner seal 120 to prevent coke from the bake pit (not shown) from entering the vertical expansion joint 130. In some embodiments, the corner seal may also comprise an inorganic fibre blanket of the present disclosure. The flue wall 100 and headwall 110, which are in contact with the inorganic fibre based refractory mastic and blanket (when present), are made from hot face refractory brick, which comprises an alumina content ranging from at least 42 wt % alumina to at least 58 wt % alumina. A sealant system comprising inorganic fibres of the present disclosure with a silica content of greater than 65.7 wt % is particularly beneficial in this application due to the fibre's non-reactivity with alumina and the fibre's low shrinkage characteristics at high temperatures.

[0243] An example of the furnace insulation system is illustrated in FIG. 7, in which insulating lining material 200 is attached to an inside surface of the furnace wall 210. The insulating material in use having a hot face 220 which faces inwardly of the furnace; and a cold face 230 in contact with the furnace wall 210, made of refractory bricks comprising alumina. The insulating lining material comprise inorganic fibres in the form of blankets, folded blanket modules or high density (e.g. up to 240 kg/m.sup.3) modules, such Pyro-Stack™ or Pyro-Bloc® type modules available from Morgan Advanced Materials.

[0244] Other Potential Uses

[0245] The fibres of the present disclosure can be used, subject to meeting relevant performance criteria, for any purpose for which fibrous inorganic materials, and particularly alkaline earth silicate and aluminosilicate materials, have been used heretofore; and may be used in future applications where the fibre properties are appropriate. The fibres and products derived therefrom of the present disclosure may be used in applications which currently use commercially available products including, but not limited to SUPERWOOL® PLUS, SUPERWOOL® HT, SUPERWOOL® XTRA™, THERMFRAX®, INSULFRAX 1300 HT, ISOFRAX® 1260, ISOFRAX® 1300, ISOFRAX® 1400, ISOFRAX® LTX™, FINEFLEX BIO™, KCC CERAKWOOL New-Bio™ 1100, CERAKWOOL New-Bio™ 1300, MINYE HB®.

[0246] In the following reference is made to a number of patent documents relating to applications in which the fibres may be used, subject to meeting relevant performance criteria for the application. The fibres of the present disclosure can be used in place of the fibres specified in any of these applications subject to meeting relevant performance criteria. For example, the fibres may be used as:— [0247] bulk materials; [0248] deshotted materials [WO2013/094113]; [0249] in a mastic or mouldable composition [WO2013/080455, WO2013/080456] or as part of a wet article [WO2012/132271]; [0250] as a constituent in needled or otherwise entangled [WO2010/077360, WO2011/084487] assemblies of materials, for example in the form of blanket, folded blanket modules, or high density fibre blocks [WO2013/046052]; [0251] as a constituent of non-needled assemblies of materials, for example felts, vacuum formed shapes [WO2012/132469], or papers [WO2008/136875, WO2011/040968, WO2012/132329, WO2012/132327]; [0252] as a constituent (with fillers and/or binders) of boards, blocks, and more complex shapes [WO2007/143067, WO2012/049858, WO2011/083695, WO2011/083696]; [0253] as strengthening constituents in composite materials such as, for example, fibre reinforced cements, fibre reinforced plastics, and as a component of metal matrix composites; [0254] in support structures for fuel cells [WO2020047036] or catalyst bodies in pollution control devices such as automotive exhaust system catalytic converters and diesel particulate filters [WO2013/015083], including support structures comprising: [0255] edge protectants [WO2010/024920, WO2012/021270]; [0256] microporous materials [WO2009/032147, WO2011019394, WO2011/019396]; [0257] organic binders and antioxidants [WO2009/032191]; [0258] intumescent material [WO2009/032191]; [0259] nanofibrillated fibres [WO2012/021817]; [0260] microspheres [WO2011/084558]; [0261] colloidal materials [WO2006/004974, WO2011/037617] [0262] oriented fibre layers [WO2011/084475]; [0263] portions having different basis weight [WO2011/019377]; [0264] layers comprising different fibres [WO2012065052]; [0265] coated fibres [WO2010122337]; [0266] mats cut at specified angles [WO2011067598]; [0267] [NB all of the above features may be used in applications other than support structures for catalytic bodies] [0268] as a constituent of catalyst bodies [WO2010/074711]; [0269] as a constituent of friction materials [e.g. for automotive brakes [JP56-16578]]; [0270] a component in insulation, fire protection or thermal runaway prevention materials in energy storage devices [ [0271] for fire protection [WO2011/060421, WO2011/060259, WO2012/068427, WO2012/148468, WO2012/148469, WO2013074968]; [0272] as insulation, for example; [0273] as insulation for ethylene crackers [WO2009/126593], hydrogen reforming apparatus [U.S. Pat. No. 4,690,690]; [0274] as insulation in furnaces for the heat treatment of metals including iron and steel [U.S. Pat. No. 4,504,957]; [0275] as insulation in apparatus for ceramics manufacturing.

[0276] The fibres may also be used in combination with other materials. For example the fibres may be used in combination with polycrystalline (sol-gel) fibres [WO2012/065052] or with other biosoluble fibres [WO2011/037634].

[0277] Bodies comprising the fibres may also be used in combination with bodies formed of other materials. For example, in insulation applications, a layer of material according to the present disclosure [for example a blanket or board] may be secured to a layer of insulation having a lower maximum continuous use temperature [for example a blanket or board of alkaline earth silicate fibres][WO2010/120380, WO2011133778]. Securing of the layers together may be by any known mechanism, for example blanket anchors secured within the blankets [U.S. Pat. No. 4,578,918], or ceramic screws passing through the blankets [see for example DE3427918-A1].

[0278] Treatment of the Fibres

[0279] In formation of the fibres or afterwards they may be treated by applying materials to the fibres. For example:— [0280] lubricants may be applied to the fibres to assist needling or other processing of the fibres; [0281] coatings may be applied to the fibres to act as binders; [0282] coatings may be applied to the fibres to provide a strengthening or other effect, for example phosphates [WO2007/005836] metal oxides [WO2011159914] and colloidal materials such as alumina, silica and zirconia [WO2006/004974]; [0283] binders may be applied to the fibres to bind the fibres subsequent to incorporation in a body comprising such fibres.

[0284] Many variants, product forms, uses, and applications of the fibres of the present disclosure will be apparent to the person skilled in the art and are intended to be encompassed by this disclosure.

[0285] By providing biosoluble fibres having maximum continuous use temperature higher than alkaline earth silicate fibres, the present disclosure extends the range of applications for which biosoluble fibres may be used. This reduces the present need, for many applications, to use fibres that are not biosoluble.

[0286] For the avoidance of doubt it should be noted that in the present specification the term “comprise” in relation to a composition is taken to have the meaning of include, contain, or embrace, and to permit other ingredients to be present. The terms “comprises” and “comprising” are to be understood in like manner. It should also be noted that no claim is made to any composition in which the sum of the components exceeds 100%.

[0287] Where a patent or other document is referred to herein, its content is incorporated herein by reference to the extent permissible under national law.

[0288] It should be understood that usage of compositions of the names of oxides does not imply that these materials are supplied as such, but refers to the composition of the final fibre expressing the relevant elements as oxides. The materials concerned may be provided in whole or in part as mixed oxides, compounded with fugitive components (e.g. supplied as carbonates) or as non-oxide components.

[0289] The term metal oxides and/or non-oxides is inclusive of all forms of metal including phosphates, sulphates, halides or sulphides.

[0290] Clause Set 1: [0291] 1. Inorganic fibres having a composition comprising: [0292] 61.0 to 70.8 wt % SiO.sub.2; [0293] 27.0 to 38.9 wt % CaO; [0294] 0.10 to 2.0 wt % MgO; and [0295] optionally, an amount of other components providing a balance up to 100 wt %, wherein a sum of SiO.sub.2 and CaO is greater than or equal to 97.8 wt % and wherein the amount of the other components, when present, comprise no more than 0.80 wt % Al.sub.2O.sub.3. [0296] 2. The inorganic fibres of clause 1, wherein the amount of MgO is configured to inhibit the formation of surface crystallite grains upon heat treatment at 1100° C. for 24 hours, wherein any said surface crystallite grains have an average crystallite size of a range of from 0.0 to 0.90 μm. [0297] 3. The inorganic fibres of clause 1 or 2, wherein the amount of other components is configured to inhibit the formation of surface crystallite grains upon heat treatment at 1100° C. for 24 hours, wherein any said surface crystallite grains have an average crystallite size of a range of from 0.0 to 0.90 μm. [0298] 4. The inorganic fibres of clause 1 or 2, wherein the amount of other components is configured to inhibit the formation of surface crystallite grains upon heat treatment at 1100° C. for 24 hours, wherein any said surface crystallite grains have an average crystallite size of a range of from 0.0 to 0.60 μm. [0299] 5. The inorganic fibres according to any one of the preceding clauses, wherein SiO.sub.2 is present in an amount configured to inhibit the reactivity of the inorganic fibres, such that the inorganic fibres are non-reactive with mullite when in contact at 1200° C. for 24 hours. [0300] 6. The inorganic fibres according to any one of the preceding clauses, wherein the sum of SiO.sub.2 and CaO is greater than or equal to 97.9 wt %. [0301] 7. The inorganic fibres according to any one of the preceding clauses, wherein the sum of SiO.sub.2 and CaO is greater than or equal to 98.0 wt %. [0302] 8. The inorganic fibres according to any one of the preceding clauses, wherein the sum of SiO.sub.2 and CaO is greater than or equal to 98.2 wt %. [0303] 9. The inorganic fibres according to any one of the preceding clauses, wherein the sum of SiO.sub.2 and CaO is greater than or equal to 98.4 wt %. [0304] 10. The inorganic fibres according to any one of the preceding clauses, wherein the sum of SiO.sub.2 and CaO is greater than or equal to 98.6 wt %. [0305] 11. The inorganic fibres according to any one of the preceding clauses, wherein the composition comprises less than 1.0 wt % MgO. [0306] 12. The inorganic fibres according to any one of the preceding clauses, wherein the composition comprises less than 0.90 wt % MgO. [0307] 13. The inorganic fibres according to any one of the preceding clauses, wherein the composition comprises less than 0.85 wt % MgO. [0308] 14. The inorganic fibres according to any one of the preceding clauses, wherein the other components comprise no more than 0.75 wt % Al.sub.2O.sub.3. [0309] 15. The inorganic fibres according to any one of the preceding clauses, wherein the other components comprise no more than 0.7 wt % Al.sub.2O.sub.3. [0310] 16. The inorganic fibres according to any one of the preceding clauses, wherein the other components comprise no more than 0.4 wt % alkaline metal oxides. [0311] 17. The inorganic fibres according to any one of the preceding clauses, wherein the other components comprise no more than 0.35 wt % alkali metal oxides. [0312] 18. The inorganic fibres of clause 1, wherein the other components comprise no more than 0.20 wt % alkali metal oxides. [0313] 19. The inorganic fibres according to any one of the preceding clauses, wherein the other components account for at least 0.3 wt % of the composition of the inorganic fibres. [0314] 20. The inorganic fibres according any one of the preceding clauses, wherein the other components comprises a range of from 0.1 to 1.4 wt % of the sum of BaO+Cr.sub.2O.sub.3+Fe.sub.2O.sub.3+HfO.sub.2+La.sub.2O.sub.3+Mn.sub.3O.sub.4+Na.sub.2O+K.sub.2O+P.sub.2O.sub.5+SrO+SnO.sub.2+TiO.sub.2+V.sub.2O.sub.5+ZrO.sub.2+ZnO. [0315] 21. The inorganic fibres according any one of the preceding clauses, wherein the other components comprises a range of from 0.1 to 1.2 wt % of the sum of BaO+Cr.sub.2O.sub.3+Fe.sub.2O.sub.3+HfO.sub.2+La.sub.2O.sub.3+Mn.sub.3O.sub.4+Na.sub.2O+K.sub.2O+P.sub.2O.sub.5+SrO+SnO.sub.2+TiO.sub.2+V.sub.2O.sub.5+ZrO.sub.2+ZnO. [0316] 22. The inorganic fibres according any one of the preceding clauses, wherein the other components comprises a range of from 0.1 to 1.0 wt % of the sum of BaO+Cr.sub.2O.sub.3+Fe.sub.2O.sub.3+HfO.sub.2+La.sub.2O.sub.3+Mn.sub.3O.sub.4+Na.sub.2O+K.sub.2O+P.sub.2O.sub.5+SrO+SnO.sub.2+TiO.sub.2+V.sub.2O.sub.5+ZrO.sub.2+ZnO. [0317] 23. The inorganic fibres according any one of the preceding clauses, wherein the other components comprises a range of from 0.1 to 0.8 wt % of the sum of BaO+Cr.sub.2O.sub.3+Fe.sub.2O.sub.3+HfO.sub.2+La.sub.2O.sub.3+Mn.sub.3O.sub.4+Na.sub.2O+K.sub.2O+P.sub.2O.sub.5+SrO+SnO.sub.2+TiO.sub.2+V.sub.2O.sub.5+ZrO.sub.2+ZnO. [0318] 24. The inorganic fibres according to any one of the preceding clauses, wherein the other components comprise no more than 1.2 wt % of the fibre composition. [0319] 25. The inorganic fibres according to any one of the preceding clauses, wherein the sum of SiO.sub.2, CaO and MgO is greater than or equal to 98.5 wt %. [0320] 26. The inorganic fibres according to any one of the preceding clauses, wherein the sum of SiO.sub.2, CaO and MgO is greater than or equal to 99.0 wt %. [0321] 27. The inorganic fibres according to any one of the preceding clauses, wherein the sum of SiO.sub.2, CaO and MgO is greater than or equal to 99.3 wt %. [0322] 28. The inorganic fibres according to any one of the preceding clauses, wherein the inorganic fibres comprises a mean arithmetic fibre diameter is less than 4.0 μm. [0323] 29. The inorganic fibres according to any one of the preceding clauses, wherein the inorganic fibres comprises a shot content (>45 μm) in the range of from 0 to 41 wt %. [0324] 30. The inorganic fibres according to any one of the preceding clauses, wherein an amount of MgO and other components are configured to obtain a vacuum cast preform of the inorganic fibres having a shrinkage of 3.5% or less when exposed to 1300° C. for 24 hrs. [0325] 31. The inorganic fibres according to any one of the preceding clauses, wherein the inorganic fibres have a dissolution rate, in a flow solubility test (pH 7.4), of at least 150 ng/cm.sup.2 hr. [0326] 32. The inorganic fibres according to any one of the preceding clauses, wherein the composition comprises 65.7 wt % or greater the sum of SiO.sub.2+optional ZrO.sub.2. 33. The inorganic fibres according to any one of the preceding clauses, wherein the inorganic fibres are non-reactive with mullite when in contact at 1200° C. for 24 hours. [0327] 34. An insulation or sealant system comprising: [0328] a. a refractory component comprising a contact surface; and [0329] b. an insulating lining or sealant material comprising inorganic fibres having a composition according to clause 32 or 33  wherein the insulating lining or sealant material is disposed against the contact surface. [0330] 35. The insulation or sealant system of clause 34, wherein the refractory component comprises mullite. [0331] 36. The insulation or sealant system according to clause 34 or 35, wherein the refractory component comprises at least 20 wt % alumina. [0332] 37. The insulation of sealant system according to clause 36, wherein the refractory component comprises at least 40 wt % alumina. [0333] 38. The insulation or sealant system according to any one of clauses 34 to 37, wherein the refractory component comprises refractory mortar, refractory mastic, refractory cement, refractory board, refractory fibre or refractory bricks. [0334] 39. A furnace, oven or kiln comprising the insulation or sealant system according to any one of the clauses 34 to 38. [0335] 40. An insulative blanket comprising the inorganic fibres according to any one of clauses 1 to 33. [0336] 41. The insulative blanket according to clause 40, wherein the inorganic fibre composition is configured for continuous use at up to 1300° C. and the blanket comprises a density of 64 kg/m.sup.3 or greater. [0337] 42. The insulative blanket according to clauses 40 or 41, wherein the thermal conductivity of a 128 kg/m.sup.3 blanket comprises a thermal conductivity of no more than 0.32 W/m.Math.K at 1200° C. [0338] 43. The insulative blanket according any one of clauses 40 to 42, wherein a 128 kg/m.sup.3 blanket comprises a strength of at least 60 kPa. [0339] 44. The insulative blanket according to any one of clauses 40 to 43 comprising a resiliency value of at least 63 wt % measured at 1150° C. for 24 hrs. [0340] 45. A process for the manufacture of inorganic fibres comprising: [0341] a. selecting a composition and proportion of each of the following raw materials: [0342] i. silica sand and [0343] ii. lime, said lime comprising at least 0.10 wt % magnesia; and [0344] iii. optional additives [0345] b. mixing the silica sand; lime; and optional additives to form a mixture; [0346] c. melting the mixture in a furnace; [0347] d. shaping the molten mixture into inorganic fibres,  wherein the raw material selection comprises composition selection and proportion selection of silica sand and lime to obtain an inorganic fibre composition comprising a range of from 61.0 wt % and 70.8 wt % silica; less than 2.0 wt % magnesia; incidental impurities; and no more than 2.0 wt % metal oxides and/or metal non-oxides derived from said optional additives, with calcia providing up the balance to 100 wt % and wherein the inorganic fibre composition comprises no more than 0.80 wt % Al.sub.2O.sub.3 derived from the incidental impurities and/or the optional additives. [0348] 46. The process according to clause 45, wherein the amount of magnesia in the inorganic fibre composition is at least 0.10 wt %. [0349] 47. The process according to clause 45 or 46, wherein the raw materials consists of lime and silica sand. [0350] 48. The process according to clause 45 or 46, wherein the inorganic fibre composition comprises no more than 1.5 wt % of metal oxides and/or metal non-oxides derived from said optional additives. [0351] 49. The process according to any one of clauses 45 to 48, wherein the composition selection and proportion selection of the raw materials is configured so that an amount of magnesia in the fibre composition is sufficient to inhibit the formation of surface crystallite grains upon heat treatment at 1100° C. for 24 hours, wherein any said surface crystallite grains comprises an average crystallite size in a range from of 0.0 to 0.90 μm. [0352] 50. The process according to any one of clauses 45 to 49, wherein the composition selection and proportion selection of the raw materials is configured to obtain a vacuum cast preform of the inorganic fibres comprising a shrinkage of 3.5% or less when exposed to 1300° C. for 24 hrs. [0353] 51. The process according to any one of clauses 45 to 50, wherein the composition selection of the raw materials involves doping amounts of selected incidental impurities into the raw materials to determine a shrinkage value of the resultant inorganic fibres when exposed to 1300° C. for 24 hrs and using the shrinkage value to determine a target composition selection range of the silica sand and lime. [0354] 52. The process according to any one of clauses 45 to 51, wherein the target composition is selected to control the shrinkage and/or crystallite grain size when the inorganic fibres are exposed to temperatures of 1100° C. or more. [0355] 53. The process according to any one of clauses 45 to 52, wherein the composition selection and proportion selection of the raw materials is configured to produce an inorganic fibre composition according to any one of clauses 1 to 33. [0356] 54. Inorganic fibres obtained or obtainable by the process according to any one of clauses 45 to 52.

[0357] Clause Set 2 [0358] 1. An insulation or sealant system comprising: [0359] a. a refractory component comprising a contact surface; and [0360] b. an insulating or sealant material comprising inorganic fibres having a composition comprising: [0361] 65.7 to 70.8 wt % SiO.sub.2; [0362] 27.0 to 34.2 wt % CaO; [0363] 0.10 to 2.0 wt % MgO; and [0364] optional other components providing the balance up to 100 wt %,  wherein the sum of SiO.sub.2 and CaO is greater than or equal to 97.8 wt %, wherein the other components, when present, comprises no more than 0.80 wt % Al.sub.2O.sub.3; wherein the insulating or sealant material is disposed against the contact surface, and wherein said refractory component comprises at least 20 wt % alumina. [0365] 2. The insulation or sealant system according any one of the preceding clauses, wherein the refractory component comprises at least 40 wt % alumina. [0366] 3. The insulation or sealant system according any one of the preceding clauses, wherein the amount of MgO and other components, when present, in the inorganic fibres are configured to inhibit the formation of surface crystallite grains upon heat treatment at 1100° C. for 24 hours, wherein said surface crystallite grains comprise an average crystallite size in a range of 0.0 to 0.90 μm. [0367] 4. The insulation or sealant system according to any one of the preceding clauses, wherein the sum of SiO.sub.2 and CaO is greater than or equal to 98.4 wt %. [0368] 5. The insulation or sealant system according any one of the preceding clauses, wherein the other components comprises a range of from 0.1 to 1.4 wt % of the sum of BaO+Cr.sub.2O.sub.3+Fe.sub.2O.sub.3+HfO.sub.2+La.sub.2O.sub.3+Mn.sub.3O.sub.4+Na.sub.2O+K.sub.2O+P.sub.2O.sub.5+SrO+SnO.sub.2+TiO.sub.2+V.sub.2O.sub.5+ZrO.sub.2+ZnO.

[0369] Clause Set 3 [0370] 1. A process for the manufacture of inorganic fibres comprising: [0371] a. selecting a composition and proportion of each of the following raw materials: [0372] i. silica sand; [0373] ii. lime, said lime comprising at least 0.10 wt % magnesia; and [0374] iii. optional additives [0375] b. mixing the silica sand; lime; and optional additives to form a mixture; [0376] c. melting the mixture in a furnace; [0377] d. shaping the molten mixture into inorganic fibres,  wherein the raw material selection comprises composition selection and proportion selection of the raw materials to obtain an inorganic fibre composition comprising a range of from 61.0 wt % and 70.8 wt % silica; less than 2.0 wt % magnesia; incidental impurities; and no more than 2.0 wt % of metal oxides and/or metal non-oxides derived from said optional additives; with calcia providing the balance up to 100 wt %; and wherein the inorganic fibre composition comprises no more than 0.80 wt % Al.sub.2O.sub.3 derived from the incidental impurities and/or the optional additives. [0378] 2. The process according to clause 1, wherein the amount of magnesia in the inorganic fibre composition is at least 0.10 wt %. [0379] 3. The process according to clause 1 or 2, wherein the amount of Al.sub.2O.sub.3 is no more than 0.70 wt %. [0380] 4. The process according to any one of the preceding clauses, wherein the amount of magnesia is no more than 0.85 wt %. [0381] 5. The process according to any one of clauses 1 to 4, wherein the inorganic fibre composition comprises no more than 1.8 wt % of metal oxides and/or metal non-oxides derived from said optional additives. [0382] 6. The process according to any one of clauses 1 to 4, wherein the inorganic fibre composition comprises no more than 1.0 wt % of metal oxides and/or metal non-oxides derived from said optional additives. [0383] 7. The process according to any one of clauses 1 to 4, wherein the inorganic fibre composition comprises no more than 0.6 wt % of metal oxides or metal non-oxides derived from said optional additives. [0384] 8. The process according to any one of clauses 1 to 4, wherein the inorganic fibre composition comprising no more than 0.2 wt % of metal oxides or metal non-oxides derived from said optional additives. [0385] 9. The process according to any one of clauses 1 to 4, wherein the inorganic fibre composition comprising no more than 0.1 wt % of metal oxides or metal non-oxides derived from said optional additives. [0386] 10. The process according to any one of the preceding clauses, wherein the optional additives are a source of oxides or non-oxides of one or more of the lanthanides series of elements, Li, Na, K, Sr, Sn, Ba, Cr, Fe, Zn, Y, Zr, Hf, Ca, B and P. [0387] 11. The process according to any one of clauses 1 to 4, wherein the raw materials consists of lime and silica sand. [0388] 12. The process according to any one of the preceding clauses, wherein the composition selection and proportion selection of the raw materials is configured so the amount of magnesia in the fibre composition is sufficient to inhibit the formation of surface crystallite grains upon heat treatment at 1100° C. for 24 hours, said surface crystallite grains comprise an average crystallite size in a range of from 0.0 to 0.90 μm. [0389] 13. The process according to any one of the preceding clauses, wherein the composition selection and proportion selection of the raw materials is configured to obtain a vacuum cast preform of the inorganic fibres comprising a shrinkage of 6.0% or less when exposed to 1300° C. for 24 hrs. [0390] 14. The process according to any one of the preceding clauses, wherein the raw material composition selection and proportion of said silica sand and lime is configured to obtain a vacuum cast preform of the inorganic fibres comprising a shrinkage of 4.0% or less when exposed to 1300° C. for 24 hrs. [0391] 15. The process according to any one of the preceding clauses, wherein the raw material composition selection and proportion of said silica sand and lime is configured to obtain a vacuum cast preform of the inorganic fibres comprising a shrinkage of 3.5% or less when exposed to 1300° C. for 24 hrs. [0392] 16. The process according to any one of the preceding clauses, wherein the composition selection and proportion selection of the raw materials is configured such that the proportion of silica and optional zirconia in the inorganic fibre composition comprises a range of from 65.7 wt % and 70.8 wt %. [0393] 17. The process according to any one of the preceding clauses, wherein the composition selection and proportion selection of the raw materials is configured such that the proportion of incidental impurities in the inorganic fibre composition is less than 2.0 wt %. [0394] 18. The process according to any one of the preceding clauses, wherein the composition selection and proportion selection of the raw materials is configured such that the proportion of incidental impurities in the inorganic fibre composition is less than 1.5 wt %. [0395] 19. The process according to any one of the preceding clauses, wherein the composition selection and proportion selection of the raw materials is configured such that the proportion of incidental impurities in the inorganic fibre composition is less than 0.8 wt %. [0396] 20. The process according to any one of the preceding clauses, wherein the composition selection and proportion selection of the raw materials is configured such that the proportion of incidental impurities in the inorganic fibre composition is less than 0.6 wt %. [0397] 21. The process according to any one of the preceding clauses, wherein the composition selection and proportion selection of the raw materials is configured such that the proportion of incidental impurities and optional additives in the inorganic fibre composition is no more than 2.5 wt %. [0398] 22. The process according to any one of the preceding clauses, wherein the composition selection and proportion selection of the raw materials is configured such that the proportion of incidental impurities and optional additives in the inorganic fibre composition is no more than 2.2 wt %. [0399] 23. The process according to any one of the preceding clauses, wherein the composition selection of the raw materials involves doping amounts of selected incidental impurities into the raw materials to determine the shrinkage value of the resultant inorganic fibres when exposed to 1300° C. for 24 hrs and using the shrinkage value to determine a target composition selection range of the silica sand and lime. [0400] 24. The process according to clause 21, wherein the target composition selection range is used to select the silica sand and/or the lime. [0401] 25. The process according to any one of the preceding clauses, wherein the composition of the silica sand and/or lime is obtained through blending different batches of silica sand and/or lime to obtain the target composition.