High temperature thermo-acoustic barrier material with low smoke and odor

Abstract

A thermal barrier material is disclosed for applications such as heat shields in automobiles and other vehicles. The thermal barrier material is made on a Fordenier paper making machine from a slurry that is very low in organic compounds that can cause smoke and odor when exposed to high temperatures. A first thermal barrier material is disclosed that can withstand up to 650° C. and a second thermal barrier material is disclosed that can withstand up to 1000° C. In each case, the barrier material withstands it max temperature specification while producing extremely low quantities of smoke and extremely low levels of offensive odors. Prior art thermal barrier materials with similar temperature specifications on the other hand produce many times the smoke and offensive odors at the same temperatures and do so for a far longer time.

Claims

1. A thermal barrier material for use in shielding components of a vehicle from hot surfaces comprising: 17 to 23% magnesium silicate by weight; 2 to 5% aluminum phyllosilicate clay by weight; 17 to 23% hydrous aluminum silicate by weight; 12 to 18% hydrous magnesium silicate by weight; 4 to 7% phyllosilicate by weight; 17 to 23% aluminum trihydrate by weight; 2 to 6% alumino-borosilicate glass by weight; 6 to 8% rock wool by weight; 1 to 6% basalt fibers by weight; 0.05 to 1.5% acrylamide copolymer coagulant by weight; 0.07 to 1.2% acrylic latex by weight; 0.01 to 0.05% fatty alcohol alkoxylate by weight; and 0.5 to 1.5% anionic polyacrylamide by weight.

2. The thermal barrier material of claim 1, wherein a sample of the thermal barrier material, when exposed to a temperature of 400° Centigrade, produces smoke having a density less than 5 g/cm.sup.3 as measured according to the ISO 5659-2:2006(E) standard.

3. The thermal barrier material of claim 1, wherein a sample of the thermal barrier material, when exposed to a temperature of 400° Centigrade, produces smoke having a density less than 2 g/cm.sup.3 as measured according to the ISO 5659-2:2006(E) standard.

4. The thermal barrier material of claim 1, wherein a sample of the thermal barrier material, when exposed to a temperature of 400° Centigrade, produces smoke having a density of about 0.88 g/cm.sup.3 as measured according to the ISO 5659-2:2006(E) standard.

5. The thermal barrier material of claim 1, wherein a sample of the thermal barrier material produces less than 4 ppm of 1-butanal gas as measured by Gas Chromatography (GC) and Mass Spectrometry (MS).

6. The thermal barrier material of claim 1, wherein a sample of the thermal barrier material produces no detected 1-butanal gas as measured by Gas Chromatography (GC) and Mass Spectrometry (MS).

7. The thermal barrier material of claim 1, wherein a sample of the thermal barrier material produces less than 150 ppm Dimethoxymethane gas as measured by Gas Chromatography (GC) and Mass Spectrometry (MS).

8. The thermal barrier material of claim 1, wherein a sample of the thermal barrier material produces about 55 ppm Dimethoxymethane gas as measured by Gas Chromatography (GC) and Mass Spectrometry (MS).

9. The thermal barrier material of claim 1, wherein a sample of the thermal barrier material does not ignite when exposed to a temperature of 650° Centigrade in a furnace.

10. A thermal barrier material for use in shielding components of a vehicle from hot surfaces, comprising: 8 to 12% magnesium silicate by weight; 2 to 5% aluminum phyllosilicate clay by weight; 8 to 12% hydrous aluminum silicate by weight; 12 to 18% hydrous magnesium silicate by weight; 4 to 7% phyllosilicate by weight; 35 to 43% aluminum trihydrate by weight; 2 to 6% alumino-borosilicate glass by weight; 6 to 8.5% rock wool by weight; 4 to 7% basalt fibers by weight; 0.05 to 1.5% acrylamide copolymer coagulant by weight; 0.05 to 0.95% acrylic latex by weight; 0.01 to 0.05% fatty alcohol alkoxylate by weight; and 0.5 to 1.5% anionic polyacrylamide by weight.

11. The thermal barrier material of claim 10, wherein a sample of the thermal barrier material, when exposed to a temperature of 400° Centigrade, produces smoke having a density less than 5 g/cm.sup.3 as measured according to the ISO 5659-2:2006(E) standard.

12. The thermal barrier material of claim 10, wherein a sample of the thermal barrier material, when exposed to a temperature of 400° Centigrade, produces smoke having a density less than 2 g/cm.sup.3 as measured according to the ISO 5659-2:2006(E) standard.

13. The thermal barrier material of claim 10, wherein a sample of the thermal barrier material, when exposed to a temperature of 400° Centigrade, produces smoke having a density of about 0.88 g/cm.sup.3 as measured according to the ISO 5659-2:2006(E) standard.

14. The thermal barrier material of claim 10, wherein a sample of the thermal barrier material produces less than 4 ppm of 1-butanal gas as measured by Gas Chromatography (GC) and Mass Spectrometry (MS).

15. The thermal barrier material of claim 10, wherein a sample of the thermal barrier material produces no detected 1-butanal gas as measured by Gas Chromatography (GC) and Mass Spectrometry (MS).

16. The thermal barrier material of claim 10, wherein a sample of the thermal barrier material produces less than 150 ppm Dimethoxymethane gas as measured by Gas Chromatography (GC) and Mass Spectrometry (MS).

17. The thermal barrier material of claim 10, wherein a sample of the thermal barrier material produces about 42.6 ppm Dimethoxymethane gas as measured by Gas Chromatography (GC) and Mass Spectrometry (MS).

18. The thermal barrier material of claim 10, wherein a sample of the thermal barrier material produces less than 100 ppm CO gas as measured according to ASTM 800 standards.

19. The thermal barrier material of claim 10, wherein a sample of the thermal barrier material produces about 46 ppm CO gas as measured according to ASTM 800 standards.

20. The thermal barrier material of claim 10, wherein a sample of the thermal barrier material produces less than 700 ppm CO2 gas as measured according to ASTM 800 standards.

21. The thermal barrier material of claim 10, wherein a sample of the thermal barrier material produces about 599 ppm CO2 gas as measured according to ASTM 800 standards.

22. The thermal barrier material of claim 10, wherein a sample of the thermal barrier material does not ignite when exposed to a temperature of 650° Centigrade in a furnace.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a perspective view of a thermo-acoustic barrier in flat sheet form that embodies principles of the invention.

(2) FIG. 2 is a side elevational view of the barrier of FIG. 1 showing the layered construction of the barrier.

(3) FIG. 3 is a perspective view of the thermo-acoustic barrier as seen from the opposite side.

(4) FIG. 4 is a photograph of a test device designed to test the cold formability of the thermal barrier material of the thermo-acoustic barrier.

(5) FIG. 5 is a photograph of a cup-shaped piece of the thermal barrier material formed according to the method of FIG. 3 and following heat and breakage test.

(6) FIG. 5a is a bar graph showing results of testing for loss of mass due to dusting for the thermal barrier of the present invention and prior art thermal barriers.

(7) FIG. 6 is a photograph showing the side-by-side testing of a prior art thermal barrier and a thermal barrier of the present invention for smoke and offensive odor emissions when heated.

(8) FIG. 7 is a chart showing results of the smoke and offensive odor test shown in FIG. 5.

(9) FIG. 8 is a photograph showing the side-by-side testing of a prior art thermal barrier and a thermal barrier of the present invention for flame ignition point when heated.

(10) FIG. 9 shows charts and associated graphs illustrating the results of side-by-side testing of a prior art thermal barrier and a thermal barrier of the present invention for thermal conductivity (thermal mapping).

(11) FIG. 10 is a chart showing results of the side-by-side testing of a prior art thermal barrier and a thermal barrier of the present invention for toxicity of gasses generated when heated.

(12) FIG. 11 is a summary chart compiling the results of various tests conducted on the TI1000 thermal barrier of the present invention and a prior art thermal barrier with similar performance specifications.

(13) FIG. 12 is a summary chart compiling the results of various tests conducted on the TI650 thermal barrier of the present invention and a prior art thermal barrier with similar performance specifications.

DETAILED DESCRIPTION

(14) Reference will now be made in more detail to the drawing figures, wherein like reference numerals indicate like parts throughout the several views. FIG. 1 illustrates a thermo-acoustic barrier that embodies principles of the invention in one preferred form. The thermo-acoustic barrier 16 comprises a high temperature thermal barrier layer 17 bonded to an acoustic absorption layer 18. The term “high temperature” as used herein means temperatures encountered adjacent hot surfaces of modern engines and exhaust systems. Such temperatures generally range from between 650° C. and 1000° C. (1112° F. and 1832° F.) but can be somewhat lower or higher in specific cases. The high temperature thermal barrier layer 17 is formulated and fabricated as detailed below to withstand high temperatures while generating very low (compared to the prior art) smoke and very low odor intensity and offensiveness.

(15) An acoustic absorption layer 18 is secured to the thermal barrier layer 17 on one side thereof. The acoustic absorption layer 18 can be secured to the thermal barrier layer by any appropriate means such as with an adhesive for example. One preferred method of securing the layers together is shown in FIGS. 2 and 3. FIG. 2 shows the thermo-acoustic barrier 16 with the acoustic absorption layer facing up and FIG. 3 shows a cross section of the thermo-acoustic barrier. In this embodiment, the acoustic absorption layer 18 is punched to form a plurality of holes 19 that extend through the acoustic absorption layer.

(16) The thermal barrier layer 17 is initially applied in the form of a slurry onto an upwardly facing surface of the acoustic absorption layer 18. The slurry flows partially into the holes 19 as perhaps best illustrated in FIG. 2. As the slurry is dewatered and dried, preferably using a Fourdrinier or other type of paper making machine, the thermal barrier material in the holes 19 dries and locks the thermal barrier layer 18 and the acoustic absorption layer 17 together with a mechanical bond.

(17) The acoustic absorption layer 18 may be formed of any material that performs the function of absorbing sound before it enters the passenger compartment of a vehicle. In the preferred embodiment, the acoustic absorption layer 18 is made of a non-woven fiberglass sound absorbing material such as that available from Owens Corning Corporation of Toledo, Ohio and other suppliers. Other possible materials that may be suitable for the acoustic absorption layer include, without limitation, cotton and organic sound absorbing batts, silica fiber mats, and sound absorbing foam to mention a few.

(18) While the thermo-acoustic barrier is shown as a flat sheet or tile in FIGS. 1 and 2, it should be understood that in use the barrier often will be shaped to fit in a specific tight space between a hot surface such as a catalytic converter and the floor panels of a vehicle. Furthermore, the thermo-acoustic panel may be adhered to one side of a shaped aluminized metal sheet or sandwiched between two metal sheets that can be pressed into a desired shape and also serve as thermal reflectors. So, the flat sheet or tile shown in the illustrative embodiment is not intended to limit the invention, but only to illustrate the layered construction of the barrier in a simple and easily understood form.

(19) As detailed below, it has been found through experimentation that the smoke and unpleasant odors often produced by prior art thermal barriers (of which consumers complain) result from the burn-off of organic binders and other organic compounds present in the material of these barriers. In contrast, the materials from which the thermal barrier of the present invention is made are very low in organic compounds and binders compared to prior art thermal barriers. In one preferred embodiment, the thermal barrier of this invention may be made as follows.

(20) Making the Thermal Barrier

(21) Table 1 below shows the ingredients used to make the thermal barrier of the present invention and, for each ingredient, the percent-by-weight of the ingredient used in a slurry to be made into the thermal barrier in a paper making machine.

(22) TABLE-US-00001 TABLE 1 TI650 TI1K Magnesium Silicate 17-23  8-12 Aluminum phyllosilicate clay 2-5 2-5 hydrous aluminum silicate 17-23  8-12 Hydrous magnesium silicate 12-18 12-18 Phyllosilicate (mica) 4-7 4-7 alumina trihydrate 17-23 35-43 alumino-borosilicate glass 2-6 2-6 dye .sup. 1-1.5  .5-1.5 Rock Wool 6-8 .sup. 6-8.5 Basalt fiber 1-6 4-7 Acrylamide Copolymer Coagulant .05-1.5 .05-1.5 Acrylic Latex .07-1.2 .05-.95 Fatty Alchol Alkoxylate .01-.05 .01-.05 Anionic polyacrylomide  .5-1.5  .5-1.5 Cellulose Fiber .sup. 1-1.8 0

(23) Except for the basalt fibers, the fibers and clays in Table 1 are combined with water (between 7 and 50° C.) into a slurry using a pulper. To maintain the length of the basalt fibers, they are added directly to the mixing chest and homogenized into the mixing stock to avoid the shear forces generated in the pulper. The latex is then added and precipitated onto the fiber and fillers. The resulting slurry is spread onto the conveyor belt at the wet end of a traditional Fourdrinier paper making machine forming a wet web of fibers. If the thermal barrier is to be combined with an acoustic absorption barrier, the slurry may be spread onto a thin sheet of the acoustic absorption material, which may have been prepared with holes to facilitate binding the two layers together. In the machine, the wet web is dewatered and dried. The resulting web can then be cut into desired shapes and molded if desired to fit into areas where it is to be used.

(24) Testing

(25) Most of the tests described below were carried out according to the corresponding established industry method (typically an ASTM standard). However, due to the subjective nature of the offensive odor testing, internal testing methods were developed that quantified the intensity and offensiveness of odors produced by prior art thermal barrier materials and by thermal barrier materials of the present invention. An objective test for the presence of chemicals known to produce offensive odors also was carried out. In addition, the thermal masking tests were conducted using an internal testing method historically used to assess various thermal conduction properties of heat shield insulating material. These tests are detailed below.

(26) 1. Cold Formability and Vibration Testing

(27) FIGS. 4 and 5 illustrate devices used to test the cold formability of thermal barrier material made according to the above described process. The test was carried out according to test method WI-TP-033_0. Both the T1650 and the TI1000 (TI1k) embodiments of the thermal barrier materials were tested. For each material, a circular sample 23 of the material was die-cut from a sheet and positioned over a spherical depression on the anvil of a press 22. A spherical ram 24 was then pressed onto the sample until the sample was urged into the depression, thereby molding the sample into a bowl-shaped configuration.

(28) After each sample was molded into a bowl shape as described, it was heated in a furnace to 400° C. for 30 minutes and then placed in a tabletop shaker 26 (FIG. 5) for 5 minutes. Flat die cut specimens that had not been molded also were heated and shaken in this manner. This test sought to simulate the heat and vibration that might be experienced by the material when used in a vehicle. If the sample breaks into several pieces after heating and shaking or displays large separations, then it is likely that the material will crack or break up during crash forming of a commercial heat shield or during normal use. As shown in the summary test results chart of FIG. 11, the test revealed for the TI650 material that there were no cracks and the sample was in-tact after heating and vibration as described. The TI1000 material was observed to exhibit some small cracks, but the sample was otherwise in-tact after heating and vibration. The conclusion is that the thermal barrier material of the present invention exhibits acceptable cold formability properties.

(29) To determine loss of mass due to dusting compared to prior art thermal barrier materials, die-cut and cold formed thermal barrier samples of the present invention and samples of prior art thermal barrier materials were tested. In each case, a sample was weighed, heated to 400° C. for 30 minutes, placed in a table top shaker for 5 minutes, and then weight again. Any loss in weight is due to dusting of material away from the sample during the heating and shaking process. FIG. 5a shows the results of these tests. As can be seen, for the three prior art samples tested, total loss of weight due to dusting (loss from die-cut sample plus loss from cold formed sample) ranged between 0.65% and 1.04%. Loss from the die cut sample was significantly less than loss from the cold formed sample for each of these prior art thermal barrier material.

(30) In stark contrast, the total loss of weight due to dusting for the TI1000 thermal barrier sample under the same test conditions was a mere 0.14% with about half of the loss (0.06%) being due to die-cut sample loss. For the TI650 sample of the present invention, total loss of weight was still a mere 0.14% but the great majority of the loss (0.12%) was due to dusting losses from the die-cut sample. The cold formed sample lost only 0.02% of its weight during the test. The conclusion is that heat barriers formed according to the present invention exhibit far less weight loss due to dusting than do the prior art heat barriers tested.

(31) 2. Smoke and Offensive Odor Test

(32) FIGS. 6 and 7 illustrate subjective testing of the thermal barrier material of this invention for the production of smoke and offensive odor at high temperatures. As discussed above, consumer complaints have focused on this unpleasant aspect of the prior art. For this test, a lab hot plate 29 was heated to 400° C. A sample of prior art thermal barrier material 28 was placed on the hot plate 29 and held down by weights 33. The material was then observed by members of a panel who focused on odor produced by the sample over time as its temperature rose. Members of the panel rated odors produced by the sample for intensity and offensiveness over a 5 minute period. All responses of the panel members were then tabulated.

(33) The same test was carried out with a sample of the TI1000 (TI1K) thermal barrier sample 29 made according to the present invention and a prior art thermal barrier with similar specifications. Again, the panel members rated the intensity and offensiveness of odors produced by the sample just as they had done with the prior art sample 28. The results of this test are shown in the chart 36 of FIG. 7, which plots the results of the tests on a scale of rating vs. time. As can be seen, the intensity of odors produced by the prior art thermal barrier material 39 was rated between 4 and 5 from 0.5 minutes until 2 minutes before slowly settling at a rating of about 1 after 2.5 minutes. The offensiveness 40 of these odors was rated even higher at 6 until 2 minutes into the test before slowly falling to 1 at 4 minutes.

(34) In contrast, the intensity 38, 42 of odors produced by the TI1000 (TI1K) and TI650 samples made according to the present invention rated very low at just above zero for the full duration of the test. Offensiveness 37, 41 of these odors for these samples rated between 1 and 1.5 at the beginning, ramping down to just above zero at one minute into the test. Thus, thermal barriers made according to the present invention showed a drastic reduction in intensity and offensiveness of odors produced at high temperatures compared to those produced by the prior art thermal barrier.

(35) In addition to these subjective tests, an objective odor evaluation was commissioned by an outside laboratory. The laboratory tested liberated gases from a sample of prior art thermal barrier material and a sample of thermal barrier material made according to the present invention when heated as described above. Gas Chromatography (GC) and Mass Spectrometry (MS) techniques were used to determine the presence of 1-butanol and Dimethoxymethane, both deemed by most humans to be associated with and indicative of offensive odors.

(36) As can be seen from the summary chart of FIG. 11, the prior art sample was determined to produce 4.58 parts per million (ppm) of 1-butanol while a sample of the present invention produced less than 3 ppm, less than 1 ppm and, in this test, no detectable 1-butanol. As for Dimethoxymethane, the prior art sample produced 190 ppm while the sample of the present invention produced less than 100 ppm, less than 50 ppm and specifically 42.6 ppm. Such levels are considered indicative of low levels of offensive odors to humans.

(37) FIG. 12 shows the same data for the TI650 thermal barrier sample vs the comparative prior art sample. The prior art sample produced 6.14 ppm of 1-butanol while the TI650 sample produced less than 4 ppm, less than 2 ppm, and in this particular test, no 1-butanol. The prior art sample produced 224 ppm Dimethoxymethane while the TI650 sample of the present invention produced less than 150 ppm, less than 100 ppm and, in this particular test, 55 ppm. Such ranges are considered to be indicative of low amounts of offensive odors. This objective testing supports the conclusions of the subjective tests that a thermal barrier of the present invention produces far less offensive odors when heated than does the prior art.

(38) The density of produced smoke for the barriers of the present invention also was measured according to the ISO 5659-2:2006(E) standard. The measured density for both the TI650 and the TI1000 (TI1K) samples was less than 5 g/cm.sup.3, less than 2 g/cm.sup.3 and more specifically measured to be about 0.88 g/cm.sup.3. Such smoke densities are considered barely detectable. As can be seen in FIG. 6, which shows the prior art sample 28 and the TI1000 (TI1K) sample 29 side-by-side on a 400° C. hotplate 27, the density of smoke 32 produced by the TI1000 sample 29 is far less than the density of smoke 31 produced by the prior art sample 28. The conclusion is that the high temperature thermal barrier material of the present invention produces negligible smoke when heated to high temperatures whereas the prior art produces significant smoke of which consumers complain.

(39) 3. Shock Flame Testing

(40) A prior art thermal barrier material and the TI1000 (TI1K) thermal barrier material of the present invention were tested to determine their tendency to ignite at high temperatures. These two products have similar maximum temperature specifications of 1000° C. The test setup is shown in FIG. 8. A furnace 43 was preheated to a temperature of 650° C. before placing a 2 inch by 6 inch prior art sample and a 2 inch by 6 inch sample of the TI1000 (TI1K) thermal barrier 46 in the furnace. A viewing port in the furnace wall allowed the flame point and smoke production, if any, to be visually determined. After a short time in the furnace, the prior art thermal barrier sample 44 caught fire 45 as seen in FIG. 8 and began to burn. This is considered a catastrophic failure of the barrier. The TI1000 (TI1K) thermal barrier sample 46 of the present invention did not ignite at 650° C. In fact, TI1000 (TI1K) thermal barrier 46 was subsequently tested at its design temperature of 1000° C. and again did not ignite or fail.

(41) Similarly, a prior art thermal barrier material and the TI650 thermal barrier material of the present invention were tested for ignition using the same procedure. These two products have similar maximum temperature specifications of 650° C. Again, the two samples were placed in a furnace pre-heated to 650° C. and observed. As shown in the photograph of FIG. 12, the prior art sample ignited and failed at this temperature while the TI650 sample of the present invention did not.

(42) 4. Thermal Mapping Tests

(43) Prior art thermal barriers and thermal barriers of the present invention were tested to determine the thermal conductivity of the material. This test is sometimes referred to as a thermal mapping test and was carried out according to ASTM standard F433. In the test, a sample of interest was placed directly on a pre-heated 400° C. hotplate. An infrared thermometer was used to map the rise in temperature of the top (exposed) side of the sample. The test was conducted for samples of thickness 0.8 mm and 1.0 mm for each of a prior art thermal barrier material, the TI650 barrier of the present invention, and the TI1000 barrier of the present invention. The results are shown in FIG. 7 where the charts on the right show graphically that the prior art thermal barrier conducted significantly more heat to its exposed face than did either the TI650 or the IT1000 samples of the present invention. This is true for both the 0.8 and 1.0 mm thicknesses of the samples.

(44) The test results are shown numerically on the left in FIG. 9. For the 0.8 mm thick samples, the exposed face of the prior art sample rose to a temperature of 324° C. while the exposed faces of the TI650 and TI1000 samples rose to only 313° C. and 304° C. respectively. Similarly for the 1.0 mm thick samples, the exposed face of the prior art sample rose to 323° C. while the exposed faces of the IT650 and TI1000 samples rose to temperatures of 312° C. and 289° C. respectively. These results demonstrate a thermal conductivity (thermal K) for the prior art thermal barrier material of 0.188 while the conductivity of the thermal barriers of this invention were 0.114 for the TI650 material and 0.095 for the TI1000 material. The conclusion is that thermal barriers of the present invention have significantly lower thermal conductivities than the prior art and transmit less heat from one surface to the opposite surface.

(45) 5. Toxicity of Generated Gases Test A sample of prior art thermal barrier material and a sample of the TI1000 (TI1K) barrier material of the present invention were tested according to ASTM standard 800 relating to Measurement of Gases Present or Generated During Fires. Specifically, gasses produced by these samples when burned were collected and analyzed using Fourier Transform Infrared Spectroscopy (FTIR) for toxic compounds contained in the resulting smoke. The testing measured the presence of the following compounds: CO; CO2; HCL; HCN; HBr; HF; NO; NO2; and SO2. With the exception of carbon monoxide (CO) and carbon dioxide (CO2), none of the toxic compounds were present. As for CO and CO2 levels in the gasses were determined and are presented in the table of FIG. 10. As can be seen, the TI1000 K (TI1K) thermal barrier material produced more than 8 times less CO and more than 13 times less CO2 than the prior art thermal barrier material, a substantial and significant improvement. The sample of the TI1000 (TI1k) thermal barrier material produced less than 100 ppm CO gas, less than 50 ppm, and about 46 ppm as measured according to ASTM 800 standards. The sample of the TI1000 (TI1K) thermal barrier material produced less than 700 ppm of CO2 gas, less then 600 ppm, and about 599 ppm as measured according to ASTM 800 standards.

(46) 6. Summary of Testing

(47) FIG. 11 presents a table comparing results of the above described testing and other tests for a sample of the TI1000 thermal barrier material. Also shown are the results of the same tests for a sample of prior art thermal barrier material with similar performance specifications. Results for the prior art sample are shown in column 4 while results for the TI1000 sample of the present invention are shown in column 5. First, the caliper (thickness) and density of each sample was measured using the indicated ASTM standards. The Caliper of the prior art sample was determined to be 0.80 mm and its density was determined to be 1.15 g/cm.sup.3. This compares to the TI1000 sample of the present invention, which had a caliper of 0.857 mm and a density of 0.90 g/cm.sup.3. The two samples were very similar in thickness and density.

(48) A horizontal flame spread test was conducted on the two samples according to SAE J369 testing standards. In this test, each sample was suspended in a horizontal orientation and a Bunsen burner was placed beneath one end of the sample. If the sample ignited and the flame did not self-extinguish, a rate at which the flame was observed to spread would be tabulated. In this test, the prior art sample did not ignite (DNI) and the sample of the TI1000 thermal barrier also did not ignite.

(49) A compression/recovery test was conducted on both samples according to ASTM F36K standards using an Armstrong Static Indentation Machine. This test measures the ability of the material to absorb compressive forces and, once compressed, how well the material returns to its original caliper. The thickness of the sample is measured and then the sample is subjected to an extreme load for a specified time sufficient to compress the material. The load is then removed and the material is allowed to rebound partially to its original thickness. The final thickness is then measured. The rebounded thickness divided by the original thickness represents the compression/rebound measurement expressed as a percentage. Greater rebound is desirable. In these tests, the prior art sample rebounded by 16/28 or 57% while the sample of the present invention rebounded by 20/27 or 74%. Thus, a thermal barrier of the present invention is more tolerant of compressive loads than the thermal barrier of the prior art.

(50) The thermal conductivity of each sample was measured according to the procedure outlined above. The results are tabulated again in the summary chart of FIG. 11.

(51) FIG. 12 presents a table comparing results of the above described testing and other tests for a sample of the TI650 thermal barrier material. Also shown are the results of the same tests for a sample of prior art thermal barrier material with similar performance specifications. As with tests for the TI1000 sample, results for the prior art sample are shown in column 4 while results for the TI650 sample of the present invention are shown in column 5. As can be seen from FIG. 12, the TI650 sample made according to the present invention performed significantly better than the prior art sample in virtually every test.

(52) The invention has been described herein in terms of example embodiments considered by the inventor to represent the best modes of carrying out the invention. It will be understood by one of skill in the art, however, that a wide gamut of additions, deletions, and modifications, both subtle and gross, can be made to the illustrative embodiments without departing from the spirit and scope of the invention, which is delineated only by the claims.