Process for manufacturing a metal carbide, nitride, boride, or silicide in powder form
10611638 · 2020-04-07
Assignee
Inventors
Cpc classification
C01B21/0761
CHEMISTRY; METALLURGY
C01P2004/61
CHEMISTRY; METALLURGY
C01P2002/70
CHEMISTRY; METALLURGY
C01P2002/72
CHEMISTRY; METALLURGY
C01P2004/51
CHEMISTRY; METALLURGY
International classification
C01B21/06
CHEMISTRY; METALLURGY
Abstract
A process for manufacturing a compound in powder form, wherein said compound is the reaction product of (i) at least one metal and/or metalloid, and (ii) at least one further element that is more electronegative than the metal and/or metalloid, which process includes steps of: mixing at least one oxide of said at least one metal and/or metalloid with a reducing agent including Ca or Mg granules or powder, and/or calcium hydride or magnesium hydride in granule or powder form, to form a mixture; exposing the mixture to a source of said at least one further element; maintaining said mixture under a H.sub.2 atmosphere at a temperature of from 950 C. to 1500 C. for 1-10 hours; and, recovering said compound in powder form; wherein said at least one further element is selected from carbon, nitrogen, boron, silicon and mixtures thereof. A compound in powder form obtainable by such a process.
Claims
1. A process for manufacturing a compound in powder form, wherein said compound is the reaction product of (i) at least one metal and/or metalloid, and (ii) at least one further element that is more electronegative than each said metal and/or metalloid, wherein the process comprises the steps of: a. mixing at least one oxide of said at least one metal and/or metalloid with a reducing agent to form a mixture, wherein the reducing agent comprises Ca, Mg, calcium hydride, magnesium hydride or a mixture thereof and is provided in the form of granules or a powder; b. contacting the mixture with a source of said at least one further element; c. maintaining said mixture under a H.sub.2 atmosphere at a temperature of from 950 C. to 1500 C. from 1 to 10 hours; and d. recovering said compound in powder form, further comprising between steps c and d the steps of: c1. switching the H.sub.2 atmosphere to an Ar or N.sub.2 atmosphere and maintaining the mixture thereunder for a period of at least 1 hour, followed by; c2. cooling under Ar or N.sub.2 atmosphere, wherein said at least one further element is selected from carbon, nitrogen, boron, silicon and mixtures thereof, wherein said compound is a metal carbide, nitride, boride, or silicide.
2. The process according to claim 1, wherein said at least one oxide comprises at least one selected from B.sub.2O.sub.3, SiO.sub.2, Sc.sub.2O.sub.3, TiO.sub.2, V.sub.20.sub.5, Cr.sub.2O.sub.3, Y.sub.2O.sub.3, ZrO.sub.2, Nb.sub.2O.sub.5, MoO.sub.3, HfO.sub.2, Ta.sub.2O.sub.5, and WO.sub.3.
3. The process according to claim 1, wherein the or each metal and/or metalloid is selected from Sc, Ti, V, Cr, Y, Zr, Nb, Mo, Hf, Ta, W, B, Si and mixtures thereof, and said at least one further element is selected from carbon, nitrogen, and mixtures thereof.
4. The process according to claim 3, wherein said at least one further element is carbon, said compound in powder form is a carbide of the or each metal and/or metalloid, and said reducing agent comprises Ca, Mg and/or calcium hydride, and wherein in step (c) said mixture is maintained under a H.sub.2 atmosphere at a temperature of from 950 C. to 1200 C. for 2-4 hours.
5. The process according to claim 3, wherein said compound in powder form is B.sub.4C, SiC, ScC, TiC, VC, Cr.sub.3C.sub.2, Cr.sub.7C.sub.3, YC.sub.2, ZrC, NbC, Nb.sub.2C, Mo.sub.2C, HfC, TaC, Ta.sub.2C, WC, W.sub.2C, or a solid mixture of two or more of these carbides.
6. The process according to claim 3, wherein said at least one further element is carbon, and wherein said compound in powder form is niobium carbide, tungsten carbide, or tungsten carbide containing tantalum as a dopant.
7. The process according to claim 1, wherein the reducing agent comprises Ca and/or calcium hydride, and wherein the ratio between the number of oxygen atoms in the oxide of said at least one metal or metalloid and the number of calcium atoms (O:Ca) is in the range of 1:(1.71.1).
8. The process according to claim 1, wherein said at least one metal or metalloid is selected from Sc, Ti, V, Cr, Y, Zr, Nb, Mo, Hf, Ta, W and mixtures thereof, and wherein said at least one further element is selected from boron, silicon, and mixtures thereof.
9. The process according to claim 8, wherein said oxide of said at least one metal or metalloid comprises at least one selected from Sc.sub.2O.sub.3, TiO.sub.2, V.sub.20.sub.5, Cr.sub.2O.sub.3, Y.sub.2O.sub.3, ZrO.sub.2, Nb.sub.2O.sub.5, MoO.sub.3, HfO.sub.2, Ta.sub.2O.sub.5, and WO.sub.3.
10. The process according to claim 1, wherein the compound in powder form has a content of oxygen of less than 2% by weight.
11. The process according to claim 1, wherein the compound in powder form has an average particle size X.sub.50 of 100 m or less.
12. The process according to claim 1, wherein said compound in powder form has a content of oxygen of less than 1% by weight and an average particle size X.sub.50 of 20 m or less.
13. The process according to claim 1, wherein maintaining said mixture under a H.sub.2 atmosphere at a temperature of from 950 C. to 1500 C. from 1 to 10 hours is in an open furnace.
14. The process according to claim 13, wherein the open furnace is a muffle open furnace.
15. The process according to claim 1, wherein maintaining said mixture under a H.sub.2 atmosphere is at a temperature of from 950 C. to 1150 C.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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DETAILED DESCRIPTION
(17) As starting materials, at least one oxide of at least one metal and/or metalloid, typically in powder form, is mixed with a reducing agent, such as calcium or magnesium, in powder form or in the form of granules.
(18) Typically, the metal/metalloid oxide used as starting material is provided in the form of a powder. The powder mixture used as starting material should preferably not be compacted. The mixture is heated to a temperature in the range of 950 C. to 1500 C., and kept under a H.sub.2 atmosphere for 1-10 hours, which should generally cover the duration of the reduction reaction.
(19) The powder mixture used as a starting material may further contain a source of said at least one further element to directly convert the formed metal(s) and/or metalloid(s) into the desired compound in powder form. Alternatively, the source of said at least one further element can be supplied by introducing one or more gaseous species containing said element(s) into the atmosphere during or after the reduction of said at least one oxide, before subjecting the reaction mixture to cooling. This results in the formation of the desired compound in powder form.
(20) The metals for use in the present invention are preferably transition metals, more preferably group IIIB, IVB, VB or VIB transition metals. Most preferably they are selected from Sc, Ti, V, Cr, Y, Zr, Nb, Mo, Hf, Ta and W. Particularly preferred are Nb, Ti, Cr, W and Ta. As regards possible mixtures of metals, a preferred example is W and Ta.
(21) The metalloids for use in the present invention are preferably group IIIA or IVA metalloids. More preferred are B and Si.
(22) Thus, preferably said at least one metal and/or metalloid is selected from the group consisting of Sc, Ti, V, Cr, Y, Zr, Nb, Mo, Hf, Ta, W, B and Si.
(23) Said at least one metal and/or metalloid may comprise more than one metal and/or metalloid, e.g. two, three, or more metals and/or metalloids. A second metal or metalloid may be present as a dopant. Such second and/or further metals and/or metalloids are preferably selected from the same options for the metals and metalloids as are given above, i.e. they are preferably selected from the group consisting of Sc, Ti, V, Cr, Y, Zr, Nb, Mo, Hf, Ta, W, B and Si. If more than one metal and/or metalloid is present, then said at least one further element should be more electronegative than all of the metals and/or metalloids present.
(24) An example of a preferred doped compound of the invention is tungsten carbide doped with tantalum. Thus, in this embodiment said at least one oxide could be a mixture of tungsten oxide and tantalum oxide.
(25) For the preparation of compounds containing more than one metal and/or metalloid, e.g. wherein the second and/or further metals and/or metalloids are present as one or more dopants, the starting oxide material may include oxides of said one or more further metals and/or metalloids. Alternatively, the source(s) of said one or more further metals and/or metalloids may be in some other form, e.g. in the form of an elemental powder, such as a powder form of iron, aluminum, nickel, or copper.
(26) The amount of dopant present in this instance and generally in the context of the present invention is typically less than 50% by weight relative to the total weight of metals present, preferably 40% or less, more preferably 30% or less, typically 20% or less, most typically 15% or less.
(27) Thus, the reactant mixture typically comprises an oxide of a first metal or metalloid and a source of a second metal or metalloid, wherein the second metal or metalloid is present in an amount of less than 50% by weight relative to the total weight of metals present, preferably 40% or less, more preferably 30% or less, typically 20% or less, most typically 15% or less.
(28) Preferably the amount of dopant is at least 0.01% by weight relative to the total weight of metals present, preferably at least 0.1%, more preferably at least 1%, typically at least 5%.
(29) Preferably, said at least one oxide of at least one metal and/or metalloid comprises at least one selected from the group consisting of B.sub.2O.sub.3, SiO.sub.2, Sc.sub.2O.sub.3, TiO.sub.2, V.sub.20.sub.5, Cr.sub.2O.sub.3, Y.sub.2O.sub.3, ZrO.sub.2, Nb.sub.2O.sub.5, MoO.sub.3, HfO.sub.2, Ta.sub.2O.sub.5, or WO.sub.3.
(30) Said at least one oxide of at least one metal and/or metalloid may be present on the surface of metal/metalloid particles or components, e.g. as a surrounding layer on a metal/metalloid particle that has been exposed to oxidizing conditions. Also, said at least one oxide may include particles containing substantial amounts of oxygen in the form of dissolved oxygen, oxide inclusions and/or oxide coatings, in such amounts that make them unfit for use in some conventional PM (powder metallurgical) techniques.
(31) The granules that may be used in the present invention, which are Ca, Mg, calcium hydride and magnesium hydride, are preferably in the size range of 0.03-2 mm.
(32) As used herein, the term powder is meant to describe a collection of particles having a size range of 50 nm-1 mm. For instance, such a powder may comprise or consist essentially of particles which would pass through a 1 mm sieve.
(33) The reducing agent preferably comprises Ca or Mg granules or powder and/or calcium hydride in granule or powder form. More preferably, it comprises Ca granules or powder and/or calcium hydride in granule or powder form. In this latter instance, the ratio between the number of oxygen atoms in the oxide of said metal or metalloid and the number of calcium atoms (O:Ca) is preferably in the range of 1:(1.7-1.1), or 1:(1.5-1.1), or 1:(1.5-1.05), or 1:(1.4-2), or 1:1.2.
(34) Said at least one further element is preferably selected from B, C, N, Si and mixtures of C and N. Preferred molar ratios of the different components in mixtures of C and N are 1:10 to 10:1 in terms of weight, more preferably 1:5 to 5:1, most preferably 1:2 to 2:1, and typically around 1:1. In one preferred aspect of the invention, said at least one further element is selected from B, C, N and mixtures of C and N.
(35) As noted above, it is also possible for B and/or Si to be present as metalloid components. When said metal or metalloid is B and/or Si, said at least one further element is typically other than B and Si.
(36) Thus, the present invention provides a process for manufacturing a compound in powder form, wherein said compound is the reaction product of (i) at least one metal and/or metalloid, and (ii) at least one further element selected from carbon, nitrogen, boron, silicon and mixtures thereof, which process comprises the steps of: a. mixing at least one oxide of said at least one metal and/or metalloid with a reducing agent, to form a mixture, wherein the reducing agent comprises Ca, Mg, calcium hydride, magnesium hydride or a mixture thereof and is provided in the form of granules or a powder; b. contacting the mixture with a source of said at least one further element; c. maintaining said mixture under a H.sub.2 atmosphere at a temperature of from 950 C. to 1500 C. for from 1 to 10 hours; and d. recovering said compound in powder form;
(37) provided that if said at least one metal and/or metalloid is boron and/or silicon, then said at least one further element is not boron or silicon.
(38) In a preferred embodiment, said at least one further element is carbon and/or nitrogen. In this instance, said compound in powder form will be a carbide, nitride, or carbonitride of said at least one metal and/or metalloid. In a more preferred aspect of the invention, said at least one further element is carbon and said compound in powder form is a carbide of said at least one metal and/or metalloid. In both of these instances, said at least one metal and/or metalloid is preferably selected from Sc, Ti, V, Cr, Y, Zr, Nb, Mo, Hf, Ta, W, B, Si, and mixtures thereof, and more preferably from Nb, Ti, Cr, W and mixtures thereof.
(39) In a preferred aspect of the invention, said compound in powder form is selected from B.sub.4C, SiC, ScC, TiC, VC, Cr.sub.3C.sub.2, Cr.sub.7C.sub.3, YC.sub.2, ZrC, NbC, Nb.sub.2C, Mo.sub.2C, HfC, TaC, Ta.sub.2C, WC, W.sub.2C, and solid mixtures of two or more of these carbides.
(40) It is possible for said at least one further element to comprise more than one element. For instance, in one embodiment both carbon and nitrogen are used in the process of the invention, in order to prepare a carbonitride of the relevant metal(s) and/or metalloid(s). In this instance the molar ratio of carbon:nitrogen is preferably 1:2 to 2:1, more preferably around 1:1.
(41) The source(s) of said at least one further element are not particularly limited. For instance, a given element may be provided in solid form, such as powder or granules containing a proportion of the desired element, which can be mixed with said at least one oxide of said at least one metal and/or metalloid and the reducing agent. By way of example, when said at least one further element includes carbon, the source may include or may be solid graphite particles. Alternatively, the source may be provided in gaseous form. By way of example, when said at least one further element includes nitrogen, the source may include or may be nitrogen gas, and when said at least one further element includes carbon, the source may include or may be methane gas. In any event, the source can be introduced before, during or after the reduction reaction, but preferably before or during the reduction reaction, typically during the reduction reaction.
(42) If said at least one further element includes boron, the source of said at least one further element may include or may be boron hydroxide or boron oxide. If said at least one further element includes silicon, the source of said at least one further element may include or may be silicon dioxide.
(43) As mentioned above, the source of said one or more further elements may be introduced before or during the reduction reaction. In these aspects of the invention, reduction of the oxide and formation of the desired compound in particle form may occur simultaneously.
(44) Step c of the process of the invention involves maintaining the mixture under a H.sub.2 atmosphere at a temperature of from 950 C. to 1500 C. for 1 to 10 hours. Preferably said temperature is from 950 C. to 1400 C., more preferably 950 C. to 1200 C., more preferably still 950 C. to 1150 C., such as around 1000 C., around 1050 C., or around 1100 C. The time for which the temperature is maintained is preferably at least 1.5 hours. The time for which the temperature is maintained is preferably 8 hours or less, more preferably 6 hours or less, and most preferably 4 hours or less. Typically it is around 2 or 3 hours, most typically around 2 hours.
(45) Said H.sub.2 atmosphere may be an atmosphere of essentially pure hydrogen or it may be a hydrogen containing atmosphere, wherein the content of hydrogen is at least 50% by volume, preferably at least 80%, more preferably at least 90%.
(46) In a preferred aspect, the process of the invention further comprises between steps (c) and (d) a step of switching the H.sub.2 atmosphere to an Ar or N.sub.2 atmosphere and then (i) maintaining the mixture thereunder for a period of time, typically at least 20 minutes, and/or (ii) cooling the mixture under Ar or N.sub.2 atmosphere. In step (i) the mixture is typically maintained at a temperature of 950 C. to 1500 C., preferably 950 C. to 1400 C., more preferably 950 C. to 1200 C., more preferably still 950 C. to 1150 C., such as around 1000 C., around 1050 C., or around 1100 C. It may conveniently just be maintained at the same temperature as was being used under the preceding H.sub.2 atmosphere. In step (i) the mixture is maintained under the Ar or N.sub.2 atmosphere for at least 20 minutes, preferably at least 40 minutes, more preferably at least 50 minutes. It can be maintained under the Ar or N.sub.2 atmosphere for longer, e.g. up to 80 minutes, or up to 2, 3 or 5 hours, but generally there is not much to be gained by exceeding 5 hours. Thus, in a preferred aspect the process of the invention as defined herein further comprises between steps (c) and (d) the steps of; c1. switching the H.sub.2 atmosphere to an Ar or N.sub.2 atmosphere and maintaining the mixture thereunder for a period of at least 1 hour, followed by; c2. cooling under Ar or N.sub.2 atmosphere.
(47) Where Ar and N.sub.2 atmospheres are mentioned as alternatives, an Ar atmosphere may be preferred in most instances, but an N.sub.2 atmosphere may be used if said at least one further element includes nitrogen, e.g. if the end product is a nitride.
(48) N.sub.2 atmosphere is generally used when said at least one further element comprises nitrogen, and otherwise an Ar may generally be used.
(49) Also, said compound in powder form obtainable by the process of the present invention may be subjected to washing and drying steps.
(50) In a preferred aspect, the process of the invention comprises the steps of: a. mixing at least one oxide of at least one metal and/or metalloid in powder form with a reducing agent comprising Ca or Mg granules or powder and/or calcium hydride in granule or powder form, to form a mixture; b. exposing the mixture to a source of carbon; c. maintaining said mixture under a H.sub.2 atmosphere at a temperature of from 950 C. to 1200 C. for 2-4 hours; and d. recovering a carbide of said at least one metal and/or metalloid in powder form.
(51) Preferably in this aspect of the invention, said at least one metal and/or metalloid is selected from Sc, Ti, V, Cr, Y, Zr, Nb, Mo, Hf, Ta, W, B, Si and mixtures thereof.
(52) In another preferred aspect of the invention, said at least one metal and/or metalloid is at least one metal (i.e. it does not include any metalloids), and said at least one further element is boron and/or silicon. More preferably said at least one further element is boron or silicon. In this aspect of the invention, the compound of the invention in powder form is a metal boride or a metal silicide. In this regard, said at least one metal is preferably selected from Sc, Ti, V, Cr, Y, Zr, Nb, Mo, Hf, Ta, W and mixtures thereof.
(53) The present invention provides compounds in powder form, which enjoy surprisingly high levels or purity and/or crystallite sizes which are surprisingly small for substances of this type.
(54) The content of oxygen in the compound in powder form of the invention is preferably 2% or less, more preferably 1.5% or less, more preferably still 1% or less, most preferably 0.8% or less.
(55) The content of hydrogen in the compound in powder form of the invention is preferably 0.5% or less, more preferably 0.1% or less, most preferably 0.05% or less.
(56) In the instance that the compound in powder form of the invention is not a nitride or carbonitride, the content of nitrogen is preferably 0.5% or less, more preferably 0.1% or less, most preferably 0.05% or less.
(57) The amount of contaminants (e.g. oxygen or nitrogen) in the final product may be determined by combustion analysis and detection by way of IR absorption (to determine oxygen levels) or by thermic conductivity (to determine nitrogen levels).
(58) As regards the particle size and particle size distribution for the compound in powder form of the invention, the X.sub.50 is preferably 80 m or less, more preferably 60 m or less, more preferably still 40 m or less, and typically 20 m or less. Typically it is at least 0.1 m, more typically at least 0.5 m.
(59) The X.sub.10 is preferably 40 m or less, more preferably 20 m or less, more preferably still 10 m or less, and typically 5 m or less. Typically it is at least 0.05 m, more typically at least 0.1 m.
(60) The X.sub.90 is preferably 100 m or less, more preferably 80 m or less, more preferably still 60 m or less, and typically 40 m or less. Typically it is at least 0.5 m, more typically at least 1 m.
(61) The SMD is preferably at least 0.1 m, more preferably at least 0.5 m. The SMD is preferably 20 m or less, more preferably 10 m or less.
(62) The VMD is preferably at least 0.1 m, more preferably at least 0.5 m. The VMD is preferably 30 m or less, more preferably 20 m or less.
(63) The S.sub.v is preferably at least 0.1 m.sup.2/cm.sup.3, more preferably at least 0.5 m.sup.2/cm.sup.3. The S.sub.v is preferably 20 m.sup.2/cm.sup.3 or less, more preferably 10 m.sup.2/cm.sup.3 or less.
(64) The S.sub.m is preferably at least 510.sup.3 cm.sup.2/g, more preferably at least 1010.sup.3 cm.sup.2/g. The S.sub.m is preferably 1010.sup.4 cm.sup.2/g or less, more preferably 810.sup.4 cm.sup.2/g or less.
(65) The above particle size and size distribution characteristics (i.e. X.sub.10, X.sub.50, X.sub.90, SMD, VMD, S.sub.v, and S.sub.m) may be measured using a Sympatec technique. Preferably they are measured using laser diffraction. Particle size distribution X.sub.50 (sometimes denoted D.sub.50) is also known as the median diameter or the medium value of the particle size distribution, and is the value of the particle diameter at 50% in the cumulative distribution. The X.sub.50 distribution is discussed at pages 216-218 of Metals Handbook, 9th Edition, Volume 7, Powder Metallurgy, American Society for Metals, Metals Park, Ohio 44073, ISBN 0-87170-013-1.
(66) The process of the present invention involves the reduction of at least one oxide of at least one metal and/or metalloid. It is preferred to perform the reduction under conditions which will avoid the initiation of a strong exothermic reaction. In this sense, a strong exothermic reaction is interpreted as an un-controlled, thermal runaway reaction. It is believed that such an uncontrolled exothermic reaction (e.g. self-ignition combustion synthesis) leads to less pure material.
(67) Steps that may be taken to control potentially strong reactions are using a specific ratio between oxygen and calcium, such as the preferred ratios specified above, and/or maintaining the reactants in non-compacted form. Nevertheless, if it is necessary to use a compacted form of reactants, these should ideally be in the form of thin plates, pellets, or granules.
(68) As regards the equipment that may be used to carry out the process of the invention, the following embodiments are preferred:
(69) For the furnace, any type of furnace suitable for working under temperatures for the reduction reaction, i.e. up to 1500 C. may be used. The furnace should also be fitted with means for supplying various types of gases, or in some cases applying vacuum. Preferably a muffle open furnace may be used to perform the process of the invention.
(70) A rectangular cross section crucible with a flat base may also be used. The crucible is preferably made of high temperature resistant material such as e.g. chromium nickel steel (253 MA). The crucible may be introduced to the furnace at each heat treatment process.
(71) As noted above, the heat treatment may be performed at different temperatures and for differing durations. The real temperature of the furnace may be measured using a thermocouple to compare it with the set temperature. The difference in temperature between real temperature and set temperature is typically less than 10 C.
(72) Containers filled with water may be used for washing the obtained product. The product of the process of the invention may be added to the water and washed. Containers for use in this regard may preferably be equipped with stirrers to stir the mixture of water and the product. Acetic acid may be added to the slurry with continuous stirring. After washing, the resulting powder is typically dried.
EXAMPLES
Example 1Preparation of Niobium Carbide
(73) Niobium oxide powder was used as the starting material for making niobium carbide powder. The starting materials were thoroughly mixed and then heat treated to conduct the reduction reaction process to achieve the niobium carbide powder. Heat treatment was performed at a temperature of 1100 C. for two hours. Heating session was performed under hydrogen gas environment and the cooling session (for one hour) was under argon gas protection for dehydrogenation. The final product powder was analyzed to evaluate the NbC powder quality.
(74) Niobium Oxide (Nb.sub.2O.sub.5) Powder:
(75) The particles sizes and their distribution in the Niobium oxide (Nb.sub.2O.sub.5) were analyzed using Sympatec technique, which used to analyze the material's particles morphology at dry status. The analysis curve was as follows:
(76) x.sub.10=3.50 m x.sub.50=21.92 m x.sub.90=47.92 m SMD=7.54 m
(77) VMD=24.51 m x.sub.16=7.20 m x.sub.84=41.34 m x.sub.99=73.88 m
(78) S.sub.V=0.80 m.sup.2/cm.sup.3 S.sub.m=7961.47 cm.sup.2/g
(79)
(80) Niobium Carbide Powder Analysis:
(81) The niobium carbide powder was analyzed using different analyses techniques. The NbC analyses results were as follows. The XRD results of the final product powder were as shown in
(82) The Sympatec (for particles size and their distribution) analysis for the final powder product is depicted in
(83) x.sub.10=0.60 m x.sub.50=1.07 m x.sub.90=2.19 m SMD=1.02 m
(84) VMD=1.26 m x.sub.16=0.67 m x.sub.84=1.91 m x.sub.99=3.54 m
(85) S.sub.V=5.88 m.sup.2/cm.sup.3 S.sub.m=58776.70 cm.sup.2/g
(86) The Sympatec curve of the final NbC powder showed that the X90 of the particles were in the range of 2.19 micron.
(87) The elemental analysis for the residuals in the final product of the niobium carbide powder was according to the following results:
(88) TABLE-US-00001 Hydrogen [%] Oxygen [%] Nitrogen [%] NbC 0.025 0.78 0.019
Niobium Carbide Powder Microstructure Investigation Using SEM Analysis:
(89) Samples of the niobium carbide powder were gold platted as preparation for the SEM analysis investigation. The SEM micrographs showed that the material consisted of large and small agglomerated particles as bulky shape and fluffy form of very fine particles. The particles were of different shapes, the majority of the particles were of close to rounded shape particles and as irregular shapes as shown in
(90) EDS Quantitative Analysis of the Niobium Carbide Powder was as Follows:
(91)
Example 2Preparation of Niobium Nitride
(92) Niobium Nitride powder was produced from the niobium oxide powder and the reducing agent by performing the reduction reaction process during heat treatment process. Heat treatment of the thoroughly mixed starting materials of the niobium oxide powder and the reducing agent granules was carried out at a temperature of 1100 C. for 2 hours. Heating session was performed under hydrogen gas protection and then 1 hour under nitrogen gas environment for nitriding.
(93) Scan condition: From 10 to 110; Step size: 0.01; Scan step time: 68 s
(94) Phase Analysis:
(95) TABLE-US-00002 Ref. Chemical Semi Quant No. Code Compound Name Formula Score [%] 1 98-007- Niobium(III) Nitride - N1 Nb1 76 67 6384 Delta 2 98-060- Niobium Nitride N1 Nb1 42 33 4392 (1/1)
(96) The Above mentioned XRD pattern showed that the final product material from the reduction reaction of the niobium oxide powder and a proper reducing agent was niobium nitride phase of material. The pattern also showed that there was no other material showed even as very minor phase.
(97) X.sub.10=1.85 m x.sub.50=8.32 m x.sub.90=19.82 m SMD=4.38 m
(98) VMD=10.00 m x.sub.16=2.76 m x.sub.84=16.73 m x.sub.99=38.38 m
(99) S.sub.V=1.37 m.sup.2/cm.sup.3 S.sub.m=13698.85 cm.sup.2/g
(100)
Example 3Preparation of Titanium Nitride Powder
(101) The starting materials were titanium dioxide powder and the certain reducing agent locally made as granules. After thoroughly mixing of the starting materials, the heat treatment was at a temperature of 1000 C. for 2 hours under Hydrogen gas protection and then 1 hour under nitrogen gas environment for nitriding.
(102)
(103) Scan condition: From 20 to 90; Step size: 0.01; Scan step time: 68 s
(104) Phase Analysis:
(105) TABLE-US-00003 Semi Chemical Quant No. Ref. Code Compound Name Formula Score [%] # 98-006- Osbornite N0.88 Ti0.88 60 72 4906 % 98-010- Titanium Nitride N0.17 Ti0.83 48 28 8614 (0.83/0.17)
(106) x.sub.10=2.29 m x.sub.50=10.31 m x.sub.90=36.89 m SMD=5.35 m
(107) VMD=15.44 m x.sub.16=3.52 m x.sub.84=26.68 m
(108) x.sub.99=75.21 m S.sub.V=1.12 m.sup.2/cm.sup.3 S.sub.m=11213.53 cm.sup.2/g
(109) TABLE-US-00004 cumulative distribution cumulative density distribution (log.) upper distribution residue fraction mean size density band limit distribution distribution in band for band x.sub.0/m Q.sub.3/% (1-Q.sub.3)/% dQ.sub.3/% x.sub.m/m q.sub.3lg 0.90 2.45 97.55 2.45 0.67 0.10 1.10 3.58 96.42 1.13 0.99 0.13 1.30 4.71 95.29 1.12 1.20 0.15 1.50 5.81 94.19 1.11 1.40 0.18 1.80 7.44 92.56 1.62 1.64 0.21 2.20 9.54 90.46 2.10 1.99 0.24 2.60 11.56 88.44 2.02 2.39 0.28 3.10 14.00 86.00 2.44 2.84 0.32 3.70 16.85 83.15 2.85 3.39 0.37 4.30 19.69 80.31 2.84 3.99 0.43 5.00 23.06 76.94 3.37 4.64 0.52 6.00 28.07 71.93 5.01 5.48 0.63 7.50 35.89 64.11 7.82 6.71 0.81 9.00 43.69 56.31 7.80 8.22 0.99 10.50 50.93 49.07 7.24 9.72 1.08 12.50 59.25 40.75 8.32 11.46 1.10 15.00 67.30 32.70 8.05 13.69 1.02 18.00 74.09 25.91 6.79 16.43 0.86 21.00 78.63 21.37 4.54 19.44 0.68 25.00 82.79 17.21 4.16 22.91 0.55 30.00 86.40 13.60 3.62 27.39 0.46 36.00 89.62 10.38 3.22 32.86 0.41 43.00 92.56 7.44 2.94 39.34 0.38 51.00 95.13 4.87 2.56 46.83 0.35 61.00 97.35 2.65 2.22 55.78 0.29 73.00 98.88 1.12 1.53 66.73 0.20 87.00 99.66 0.34 0.78 79.69 0.10 103.00 99.93 0.07 0.27 94.66 0.04 123.00 100.00 0.00 0.07 112.56 0.01 147.00 100.00 0.00 0.00 134.47 0.00 175.00 100.00 0.00 0.00 160.39 0.00 evaluation: WINDOX 5.4.1.0, product: Fe-pulver R3 HRLD stabil.1 reference measurement: 04-16 14:41:04 C.sub.opt = 10.67% trigger condition: PQC dispersing method: 40%, 1.0 mm vibricontrol, 6% time base: 100,00 ms cascade: 0 start: c.opt >=2.1% pressure: 3.05 bar, vacuum: 107.00 mbar valid: always revolution: 0.00% stop: 5 s c.opt <=1.9% or 99 s real time doser: VIBRI, feed rate: 40.00%
User Parameters:
(110)
Example 4Preparation of Titanium Carbide Powder
(111) Target titanium carbide powder was prepared from starting materials of TiO.sub.2, Graphite and CaH.sub.2 granules. Heat treatment was performed at a temperature of 1050 C. for 2 hrs under hydrogen gas protection and cooling for one hour was under argon gas environment for de hydrogenation. SEM micrographs are depicted in
(112) Scan condition: From 20 to 90; Step size: 0.01; Scan step time: 68 s
(113) Phase Analysis:
(114) TABLE-US-00005 Compound Chemical Semi No. Ref. Code Name Formula Score Quant [%] 1 98-060- Khamrabaevite C1 Ti1 84 100 0226
Example 5Preparation of Chromium Carbide Powder
(115) Target Chromium carbide powder was prepared from the starting materials of Cr.sub.2O.sub.3, Graphite and CaH.sub.2 granules. Heat treatment was performed at a temperature of 1050 C. for 2 hrs under hydrogen gas protection and cooling for one hour was under argon gas environment for de hydrogenation. The SEM micrographs are depicted in
(116) Scan condition: From 20 to 90; Step size: 0.01; Scan step time: 68 s