CN101774809A - Method for preparing silicon nitride and silicon carbide compounded powder through self-propagating combustion - Google Patents
Method for preparing silicon nitride and silicon carbide compounded powder through self-propagating combustion Download PDFInfo
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- CN101774809A CN101774809A CN201010120054A CN201010120054A CN101774809A CN 101774809 A CN101774809 A CN 101774809A CN 201010120054 A CN201010120054 A CN 201010120054A CN 201010120054 A CN201010120054 A CN 201010120054A CN 101774809 A CN101774809 A CN 101774809A
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Abstract
The invention discloses a method for preparing silicon nitride and silicon carbide compounded powder through self-propagating combustion, which is characterized by comprising treatment of raw materials, batching, mixing, self-propagating combustion to obtain finished products and other processing steps. The weight ratio of raw materials in the batching step is as follows: 45-50 percent by weight of metal silicon powder, 5-10 percent by weight of high-purity carbon black and 45 percent by weight of diluent. The invention has the advantages that the process is simple, the product purity is high, the investment is low, the prepared powder has good sintering activity, the whole process is simple and reliable, and large-scale production can be easily realized.
Description
Technical field:
The invention belongs to field of inorganic nonmetallic material, be specifically related to a kind of method that adopts preparing silicon nitride and silicon carbide compounded powder through self-propagating combustion, the silicon nitride and silicon carbide compounded powder of preparation can be widely used in fields such as fine ceramics and high-end refractory materials.
Background technology:
Because the silicon nitride composite silicon carbide ceramic has unique physical and mechanical property, for example density is low, high strength, high rigidity, wear-resistant, corrosion-resistant, good thermostability, has a wide range of applications in fields such as Aeronautics and Astronautics, chemical industry, the energy, machinofacture, weapon industry, Metal smeltings.
The traditional method of the silicon nitride and silicon carbide compounded powder of preparation adopts single beta-silicon nitride powder and silicon carbide powder to mix at present, to synthesize separately silicon nitride and silicon carbide powder, this method is the most effective of synthesizing silicon nitride complex silicon carbide powder and is relative simple method, is the method for widespread usage in the industry.Its complex procedures, and blended silicon nitride and silicon carbide compounded powder mixed effect is bad, has caused the production cost of silicon nitride composite silicon carbide ceramic higher, the shortcoming that energy consumption is bigger.
From climing combustion high temperature synthetic technology (Self-propagation High-temperature Synthesis, abbreviation SHS), also claiming combustion synthesis technology (Combustion Synthesis, the CS that writes), is to utilize a kind of mode that exothermic heat of reaction and conduction mode are certainly come synthetic materials between the reactant.When reactant in case ignited, just can be from the still unreacted regional spread of trend, until reacting completely, whole process needs the external world to provide any energy and reaction times very fast hardly, is a kind of method of the synthetic powder that receives much attention.But prepare aspect the silicon nitride and silicon carbide compounded powder adopting, do not appear in the newspapers as yet from climing combustion high temperature synthetic technology.
Summary of the invention:
The objective of the invention is to overcome the deficiency of above-mentioned prior art, and provide a kind of method of preparing silicon nitride and silicon carbide compounded powder through self-propagating combustion, problem such as solve mainly that existing method is produced the silicon nitride and silicon carbide compounded powder complex procedures, mixed effect is bad, production cost is higher and energy consumption is bigger.
In order to achieve the above object, the present invention is achieved in that the method for preparing silicon nitride and silicon carbide compounded powder through self-propagating combustion, and its special character is that it comprises the steps:
(1) raw material is handled: to granularity is that 300 purpose metallic silicon powers carried out the high speed ball-milling processing 12-16 hour, improves the activity of silica flour, and wherein the purity of silica flour is greater than 98.5%, silica flour is done through mechanize and is mixed, promptly adopt planetary ball mill, be placed in the cylinder of steel, with steel ball as ball-milling medium;
(2) batching: with the metallic silicon power after the above-mentioned processing is raw material, adds carbon dust, thinner, and its weight percent is:
Metallic silicon power (handling the back): 45-50wt%,
High-purity carbon black: 5-10wt%
Thinner: 45wt%,
Above-mentioned thinner is stated and is that beta-silicon nitride powder, median size are 3-10 μ m;
(3) mix: the mixture of batching step was stirred 1-4 hour, make its thorough mixing even, taking out the back sieves with 40 eye mesh screens, described stirring is that mechanize is dried mixed, promptly adopting jar mill to carry out stirring ball-milling, be placed in the corundum jar, is ball-milling medium with the steel ball, material: the ball weight ratio is 1: 2~5, and the material after mixing is crossed 40 eye mesh screens;
(4) from climing combustion reaction: the powder after above-mentioned the sieving is contained in the half-terete graphite boat, be placed on again in climing combustion reactor, after vacuumizing, fill high pure nitrogen, pressure remains on 5MPa, igniting guiding high temperature is synthetic from climing combustion, can be wound in spirrillum by the tungsten filament of 0.6mm, continue to feed the direct current of 10-20A, make coil heating, temperature has reached the temperature of reaction of silica flour and nitrogen in the raw mix, generates beta-silicon nitride powder, the reaction liberated heat causes two reactions to generate silicon carbide powder, reacts completely until carbon dust:
Si+C→SiC
Si
3N
4+C→SiC+N
2
Si powder and carbon dust are thermopositive reaction, and the reaction of silicon nitride and carbon dust is thermo-negative reaction, because this reaction is less important reaction, general reaction is still emitted heat, chemical reaction mode with climing combustion in material successively advances then, finishes until building-up reactions, the logical recirculated water cooling of synthetic post-reactor;
(5) get finished product: reaction post-reactor internal pressure can raise more than the 8MPa, after reaction finishes, pressure descends, when the pressure of reactor drops to 6MPa when following, pressure in the releasing reactor, obtain dark green, loose block product, be silicon nitride and silicon carbide compounded powder, obtain the silicon nitride and silicon carbide compounded powder finished product after the fine grinding.
The method of preparing silicon nitride and silicon carbide compounded powder through self-propagating combustion of the present invention, the product purity height that is obtained, sintering activity is good.Silica flour behind the ball milling provides a spot of amorphous silica powder for reaction, improved initial combustion combustion reactant activity, add a certain amount of silicon nitride and silicon carbide compounded powder, control the temperature of reaction on the one hand, the temperature field uniform distribution at each position of control reaction mass system has prevented the generation of too much molten silicon, adjusted the porosity of material simultaneously, be beneficial to the nitriding reaction, realized the complete nitrogenize of silica flour, guaranteed from climing combustion reacting balance, continued, carry out fast.
Compared with the prior art the method for preparing high silicon nitride and silicon carbide compounded powder from climing combustion of the present invention has outstanding substantive distinguishing features and marked improvement: 1) starting material are convenient can get, and need not special processing such as pickling; 2) synthesising reacting time is rapid, the production efficiency height, and entire reaction period (comprising batch mixing, building-up reactions, synthetics processing) 50-60 minute is easy to suitability for industrialized production; 3) save energy outside ignition reaction, does not need external heat source, and building-up reactions relies on raw material id reaction liberated heat to keep from climing combustion, and save energy has reduced cost; 4) because temperature and speed of response when having controlled reaction preferably, the transformation efficiency height of reaction, synthetic product purity height, the crystal grain rule is convenient to grind aftertreatment; 5) technology is simple, the product purity height, and less investment, the powder sintering activity of preparation is good, and whole operation is simple and reliable, is easy to realize scale operation.
Description of drawings:
Fig. 1 is the powder scanning electron microscope microscopic analysis figure of embodiment 1 from climing combustion synthetic product sampling;
Fig. 2 is the powder scanning electron microscope microscopic analysis figure of embodiment 2 from climing combustion synthetic product sampling;
Fig. 3 is the powder scanning electron microscope microscopic analysis figure of embodiment 3 from climing combustion synthetic product sampling.
Embodiment:
In order to understand better and to implement, describe the method for preparing silicon nitride and silicon carbide compounded powder through self-propagating combustion of the present invention in detail below in conjunction with embodiment.
Embodiment 1, with 300 purpose metallic silicon powers, and purity>98.5%, iron level<0.8% is a ball-milling medium with the steel ball, is placed in the cylinder of steel, material: the ball weight ratio is 1: 2, carries out 12 hours ball-milling processing on planetary ball mill; Silica flour behind the ball milling is as the raw material of next step batch mixing; By weight metallic silicon power (behind the ball milling) is 50%, weight is 1000 grams, high-purity carbon black is 5%, weight is 100 grams, beta-silicon nitride powder is 45% (median size is 3 μ m), weight is 900 grams, after the mixing, with the steel ball is ball-milling medium, be placed in the corundum jar, material: the ball weight ratio is 1: 2, be placed on the jar mill stirring ball-milling 1 hour, material after mixing is crossed 40 eye mesh screens, material after sieving is positioned in the half-terete graphite boat of porous uniformly, put into then from climing combustion synthesis reactor, after vacuumizing, charge into the high pure nitrogen of 5MPa, tungsten filament with diameter 0.6mm is made heating element, continue to feed the electric current of 10A, make coil heating, temperature has reached the temperature of reaction of silica flour and nitrogen in the raw mix, chemical reaction mode with climing combustion in material successively advances then, reaction times continues 27 minutes post-reactor internal pressures and begins to descend, and the logical recirculated water cooling of reactor this moment is when the pressure of reactor drops to 6MPa, pressure in the releasing reactor, open the product that reactor takes out loose shape then, the product integral body that obtains is dark green, and no black particle exists, chemical analysis shows that no carbon dust retains in the reactant, show that carbon dust has fully participated in reaction and generated silicon carbide powder, remaining silica flour and the nitrogen generation beta-silicon nitride powder that reacts, formation silicon nitride and silicon carbide compounded powder.
The scanning electron microscope microscopic analysis shape appearance figure of synthetic product is seen Fig. 1 in this example.
Embodiment 2, with 300 purpose metallic silicon powers, purity>98.5%, iron level<0.8% is a ball-milling medium with the steel ball, is placed in the cylinder of steel, material: the ball weight ratio is 1: 5, carries out 16 hours ball-milling processing on planetary ball mill, and the silica flour behind the ball milling is as the raw material of next step batch mixing; By weight metallic silicon power (behind the ball milling) is 45%, weight is 900 grams, high-purity carbon black is 10%, weight is 200 grams, beta-silicon nitride powder is 45% (median size is 10 μ m), weight is 900 grams, after the mixing, with the steel ball is ball-milling medium, be placed in the corundum jar, material: the ball weight ratio is 1: 5, be placed on the jar mill stirring ball-milling 4 hours, material after mixing is crossed 40 eye mesh screens, material after sieving is positioned in the half-terete graphite boat of porous uniformly, put into then from climing combustion synthesis reactor, after vacuumizing, charge into the high pure nitrogen of 5MPa, tungsten filament with diameter 0.6mm is made heating element, continue to feed the electric current of 20A, make coil heating, temperature has reached the temperature of reaction of silica flour and nitrogen in the raw mix, chemical reaction mode with climing combustion in material successively advances then, reaction times continues 32 minutes post-reactor internal pressures and begins to descend, and the logical recirculated water cooling of reactor this moment is when the pressure of reactor drops to 6MPa, pressure in the releasing reactor, open the product that reactor takes out loose shape then, the product integral body that obtains is dark green, and no black particle exists, chemical analysis shows that no carbon dust retains in the reactant, show that carbon dust has fully participated in reaction and generated silicon carbide powder, remaining silica flour and the nitrogen generation beta-silicon nitride powder that reacts, formation silicon nitride and silicon carbide compounded powder.
The scanning electron microscope microscopic analysis shape appearance figure of synthetic product is seen Fig. 2 in this example.
Embodiment 3, with 200 purpose metallic silicon powers, and purity>98.5%, iron level<0.8% is a ball-milling medium with the steel ball, is placed in the cylinder of steel, material: the ball weight ratio is 1: 3, carries out 14 hours ball-milling processing on planetary ball mill; Silica flour behind the ball milling is as the raw material of next step batch mixing; By weight metallic silicon power (behind the ball milling) is 47%, weight is 940 grams, high-purity carbon black is 8%, weight is 160 grams, beta-silicon nitride powder is 45% (median size is 6 μ m), weight is 900 grams, after the mixing, with the steel ball is ball-milling medium, be placed in the corundum jar, material: the ball weight ratio is 1: 4, be placed on the jar mill stirring ball-milling 3 hours, material after mixing is crossed 40 eye mesh screens, material after sieving is positioned in the half-terete graphite boat of porous uniformly, put into then from climing combustion synthesis reactor, after vacuumizing, charge into the high pure nitrogen of 5MPa, tungsten filament with diameter 0.6mm is made heating element, continue to feed the electric current of 15A, make coil heating, temperature has reached the temperature of reaction of silica flour and nitrogen in the raw mix, chemical reaction mode with climing combustion in material successively advances then, reaction times continues 29 minutes post-reactor internal pressures and begins to descend, and the logical recirculated water cooling of reactor this moment is when the pressure of reactor drops to 6MPa, pressure in the releasing reactor, open the product that reactor takes out loose shape then, the product integral body that obtains is dark green, and no black particle exists, chemical analysis shows that no carbon dust retains in the reactant, show that carbon dust has fully participated in reaction and generated silicon carbide powder, remaining silica flour and the nitrogen generation beta-silicon nitride powder that reacts, formation silicon nitride and silicon carbide compounded powder.
The scanning electron microscope microscopic analysis shape appearance figure of synthetic product is seen Fig. 3 in this example.
Claims (5)
1. the method for preparing silicon nitride and silicon carbide compounded powder through self-propagating combustion is characterized in that it comprises the steps:
(1) raw material is handled: to granularity is that 300 purpose metallic silicon powers carried out ball-milling processing 12-16 hour;
(2) batching: with the metallic silicon power after the above-mentioned processing is raw material, adds high-purity carbon black, thinner, and its weight percent is:
Metallic silicon power: 45-50wt%,
High-purity carbon black: 5-10wt%,
Thinner: 45wt%,
Above-mentioned thinner is stated and is that beta-silicon nitride powder, median size are 3-10 μ m;
(3) mix:, take out the back and sieves with 40 eye mesh screens with the mixture stirring ball-milling of batching step 1-4 hour;
(4) from climing combustion reaction: the powder after above-mentioned the sieving is contained in the half-terete graphite boat, is placed in climing combustion reactor again, after vacuumizing, charge into high pure nitrogen, pressure remains on 5MPa, and igniting guiding high temperature is synthetic from climing combustion, the logical recirculated water cooling in synthetic back;
(5) get finished product: reaction post-reactor internal pressure can raise more than the 8MPa, and after reaction finished, pressure descended, when the pressure of reactor drops to 6MPa when following, pressure in the releasing reactor obtains dark green, loose block product, obtains the silicon nitride and silicon carbide compounded powder finished product after the fine grinding.
2. the method for preparing silicon nitride and silicon carbide compounded powder through self-propagating combustion according to claim 1, the purity that it is characterized in that described metallic silicon power is greater than 98.5%.
3. the method for preparing silicon nitride and silicon carbide compounded powder through self-propagating combustion according to claim 1 is characterized in that described raw material treatment step adopts planetary ball mill to grind, be placed in the cylinder of steel, with steel ball as ball-milling medium.
4. the method for preparing silicon nitride and silicon carbide compounded powder through self-propagating combustion according to claim 1 is characterized in that described mixing step adopts jar mill to carry out stirring ball-milling, is placed in the corundum jar, being ball-milling medium in the steel ball.
5. the method for preparing silicon nitride and silicon carbide compounded powder through self-propagating combustion according to claim 1, it is characterized in that described igniting guiding high temperature from climing combustion reactions steps is synthetic from climing combustion, be that nichrome wire by 0.6mm is wound in spirrillum, continue to feed the direct current of 10-20A, make coil heating, temperature has reached the temperature of reaction of silica flour and nitrogen in the raw mix, and chemical reaction mode with climing combustion in material successively advances then, finish until reaction.
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Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
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CN102784921A (en) * | 2012-08-21 | 2012-11-21 | 江西稀有稀土金属钨业集团有限公司 | Preparing method and system of mixture of hard alloy and spraying particle |
CN103979539A (en) * | 2014-05-26 | 2014-08-13 | 江西科技师范大学 | Method for preparing silicon nitride/silicon carbide by utilizing cutting wastes of polycrystalline silicon and monocrystalline silicon |
CN105483823A (en) * | 2015-12-04 | 2016-04-13 | 烟台同立高科新材料股份有限公司 | Silicon nitride powder for solar polysilicon ingot casting and preparation method thereof |
CN105503198A (en) * | 2015-11-30 | 2016-04-20 | 衡阳凯新特种材料科技有限公司 | Silicon nitride material and preparation method thereof |
CN109650903A (en) * | 2019-01-14 | 2019-04-19 | 江苏大学 | A kind of carbon solid solution nitriding silicon materials and preparation method thereof |
CN115073185A (en) * | 2021-03-15 | 2022-09-20 | 中国科学院上海硅酸盐研究所 | Green silicon nitride mobile phone backboard material |
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2010
- 2010-03-05 CN CN201010120054A patent/CN101774809A/en active Pending
Non-Patent Citations (1)
Title |
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《中国粉体技术》 20070831 吴澜尔 等 自蔓延燃烧合成SiC-Si3N4复合粉末的研究 49-52 1-5 第13卷, 2 * |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
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CN102784921A (en) * | 2012-08-21 | 2012-11-21 | 江西稀有稀土金属钨业集团有限公司 | Preparing method and system of mixture of hard alloy and spraying particle |
CN103979539A (en) * | 2014-05-26 | 2014-08-13 | 江西科技师范大学 | Method for preparing silicon nitride/silicon carbide by utilizing cutting wastes of polycrystalline silicon and monocrystalline silicon |
CN105503198A (en) * | 2015-11-30 | 2016-04-20 | 衡阳凯新特种材料科技有限公司 | Silicon nitride material and preparation method thereof |
CN105483823A (en) * | 2015-12-04 | 2016-04-13 | 烟台同立高科新材料股份有限公司 | Silicon nitride powder for solar polysilicon ingot casting and preparation method thereof |
CN109650903A (en) * | 2019-01-14 | 2019-04-19 | 江苏大学 | A kind of carbon solid solution nitriding silicon materials and preparation method thereof |
CN115073185A (en) * | 2021-03-15 | 2022-09-20 | 中国科学院上海硅酸盐研究所 | Green silicon nitride mobile phone backboard material |
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Application publication date: 20100714 |