CN1055324C - Amorphous in-situ synthesized nm silicon nitride crystal whisker - Google Patents
Amorphous in-situ synthesized nm silicon nitride crystal whisker Download PDFInfo
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- CN1055324C CN1055324C CN94110355A CN94110355A CN1055324C CN 1055324 C CN1055324 C CN 1055324C CN 94110355 A CN94110355 A CN 94110355A CN 94110355 A CN94110355 A CN 94110355A CN 1055324 C CN1055324 C CN 1055324C
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- whisker
- crystal whisker
- si3n4
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- 229910052581 Si3N4 Inorganic materials 0.000 title claims abstract description 30
- 239000013078 crystal Substances 0.000 title abstract description 12
- 238000011065 in-situ storage Methods 0.000 title description 7
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 title description 2
- 238000000034 method Methods 0.000 claims abstract description 27
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 13
- 238000003786 synthesis reaction Methods 0.000 claims abstract description 13
- 239000000843 powder Substances 0.000 claims abstract description 12
- 239000002994 raw material Substances 0.000 claims abstract description 11
- 239000012299 nitrogen atmosphere Substances 0.000 claims abstract description 5
- 238000004519 manufacturing process Methods 0.000 claims abstract description 4
- 238000000197 pyrolysis Methods 0.000 claims description 10
- 238000002360 preparation method Methods 0.000 claims description 9
- 239000007789 gas Substances 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 abstract description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 abstract description 5
- 229910052760 oxygen Inorganic materials 0.000 abstract description 5
- 239000001301 oxygen Substances 0.000 abstract description 5
- 238000009776 industrial production Methods 0.000 abstract description 2
- 238000001149 thermolysis Methods 0.000 abstract 2
- 239000000654 additive Substances 0.000 abstract 1
- 230000000274 adsorptive effect Effects 0.000 abstract 1
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Inorganic materials [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 9
- 229910052710 silicon Inorganic materials 0.000 description 8
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 6
- 239000012535 impurity Substances 0.000 description 5
- 239000010703 silicon Substances 0.000 description 5
- 239000007787 solid Substances 0.000 description 5
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 229910052736 halogen Inorganic materials 0.000 description 3
- 239000000543 intermediate Substances 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- 239000007790 solid phase Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 229910021417 amorphous silicon Inorganic materials 0.000 description 2
- 239000012298 atmosphere Substances 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 150000002367 halogens Chemical class 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000001727 in vivo Methods 0.000 description 2
- 238000010899 nucleation Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 230000003014 reinforcing effect Effects 0.000 description 2
- 229910018125 Al-Si Inorganic materials 0.000 description 1
- 229910018520 Al—Si Inorganic materials 0.000 description 1
- 229910002555 FeNi Inorganic materials 0.000 description 1
- 229910003822 SiHCl3 Inorganic materials 0.000 description 1
- 229910004205 SiNX Inorganic materials 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 238000005345 coagulation Methods 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 239000006184 cosolvent Substances 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000005496 eutectics Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 238000010574 gas phase reaction Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 150000001282 organosilanes Chemical class 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000003746 solid phase reaction Methods 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
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Abstract
The present invention relates to a method for preparing a Si3N4 crystal whisker, which is characterized in that the Si3N4 crystal whisker is prepared by the thermolysis of Si/N/C powder as raw material in a nitrogen atmosphere. The crystal whisker has the characteristic reaction formula that Si/N/C and surfacial O are reacted into Si3N4 (grains), SiO (g), CO (g), 3SiO (g), 3CO (g) and 2N2 (g), and the Si3N4 (grains), the SiO (g), the CO (g), the 3SiO (g), the 3CO (g) and the 2N2 (g) are reacted into Si3N4 (W) and 3CO2 (g). The powder is prepared from SiNxCy, wherein X is not larger than 1 and is not smaller than 1, and y is not larger than 2 and is not smaller than 1. The range of surfacially adsorptive oxygen is from 5 to 10 wt %. The thermolysis synthesis is conducted at a temperature of 1500 to 1900 DEG C under air pressure of 0.5 to 2 atm for 0.5 to 4 hours. The present invention has the advantages of no need of other additives, no need of post treatment, simple production process and low cost and is suitable for industrial production.
Description
The invention relates toAnd Si3N4Preparation technology of crystal whisker, in particular to preparation of high-quality Si by in-situ synthesis of nano amorphous Si/N/C powder3N4A method of whisker.
Si3N4The whisker has light weight, high melting point, corrosion resistance, thermal shock resistance, good toughness and high-temperature strength, is a toughening and reinforcing component with various physical, chemical and mechanical properties, and can be used for toughening and reinforcing light metal (such as Al-Si)3N4(W)), ceramics (e.g.: si3N4(P)/Si3N4(W)，SiC(P)/Si3N4(W)), and a polymer. The preparation method comprises the following steps: (1) carbon thermal method: the carbothermic process mainly uses SiO2(or Si-containing oxide) and solid phase C are taken as reactants, solid phase reaction is carried out at 1400-1600 ℃ in nitrogen atmosphere to generate SiO and CO gas, and the gas and N2Reaction to form Si3N4A whisker. The reaction generally needs to add FeNi or Co as catalyst in advance, Si3N4The growth of the crystal whisker is carried out through a gas-liquid-solid propagation process, namely SiO, CO and N in low-melting-point cosolvent drops formed in advance by Si, Fe and the like2Reaching a certain supersaturation degree, and making Si undergo the process of liquid-solid coagulation3N4And (4) performing directional growth. The low melting point eutectic can also be a silicate system containing silicon and oxygen, and the method has three main defects in terms of reaction process and whisker generation: (1) SiO 22Mixing with C proportionally, if it is too heavy or reaction condition changes, it will be retained in whisker to cause impurity, C is excessive, and whisker needs to be decarbonized; (2) SiO 22The dynamic process of the contact reaction with solid phase or gas-solid interface of solid particles C is slow, and the conversion rate and the preparation efficiency are influenced; (3) VLS Si of SiO + C3N4Whisker growth generally results in the head of the whisker to be left with spherical low-melting-point amorphous globules, such as FeC, silicate, the existence of which is one of the important factors influencing the structural application thereof. However, since the raw materials SiO and C of the method have low cost, the method supplies Si with relative quality in small batches3N4The main preparation technology of whiskers is now commercialized in small quantities in Japan and USA. Reaction of this methodThe formula can be expressed as:(2) silicon nitridation: the silicon nitridation is that silicon powder forms silicon steam or molten Si and N at high temperature in nitrogen atmosphere2Generating exothermic reaction, growing Si on certain cooling substrate by impurity nucleation according to VLS mechanism3N4The whisker is characterized by comprising the following reaction formula: the method has the advantages of high cost of raw material Si, low yield and certain impurities, and is limited to the laboratory research level at present. (3) Pyrolysis of silicon-containing halogen: the process is generally carried out with a silicon-halogen-containing gas or liquid, such as SiHCl3、SiHBr3、(CH3)SiCl3At NH3The pyrolysis in gas takes place in the gas phase or in the liquid phase to form intermediates such as Si (NH)4、Si3N4Adding SiO into the intermediate2And catalysts such as Fe, Ni and the like and C atmosphere are subjected to solid phase pyrolysis, and a typical reaction can be expressed as: the halogen pyrolysis method has the defects of complex process, corrosive raw materials and high impurity content in the raw materials. (4) Silicone pyrolysis method: the method generally adopts organosilane monomer or polymer thereof to pyrolyze in proper temperature and atmosphere to directly form Si3N4The whisker is prepared by pyrolyzing the whisker or an intermediate formed firstly, the method is novel, the prepared product is generally longer, also called fiber, generally contains more organic matters, and needs to be removed by subsequent heat treatment.
The invention aims to provide high-quality Si which does not need other auxiliary agents and post-treatment, has simple production process and low cost and is suitable for industrial production3N4The preparation technology of the whisker.
The invention provides a method for preparing Si3N4A method of whisker, characterized in that: Si/N/C powder is used as raw material and is pyrolyzed under nitrogen atmosphere to form Si3N4Whisker; the method is characterized by comprising the following reaction formula: the powder is composed of SiNxCyX is more than or equal to 0.1 and less than or equal to 1, y is more than or equal to 1 and less than or equal to 2, X is more than or equal to 5-10 wt% of surface adsorbed oxygen, preferably X is more than or equal to 0.4 and less than or equal to 0.6, y is more than or equal to 1 and less than or equal to 1.5, and the pyrolysis synthesis temperature is more than or equal to 6-8 wt% of: 1500-1900 ℃, the time is 0.5-4 h, and the gas pressure is preferably 1600-1800 ℃: 0.5 to 2atm
The invention is based on that the nano amorphous Si/N/C powder is a stable material mixed with Si, N and C elements at an atomic level, and is decomposed under a certain condition when Si is used3N4For phase stabilization, crystallization to form Si3N4And C is removed. The powder has small granularity, large specific surface area and strong surface oxygen adsorption characteristic, so that CO is formed by surface oxygen and in-vivo C and is released during pyrolysis, and meanwhile, SiO is released by combination of in-vivo Si and surface O. When the concentration of CO and SiO reaches a certain value, these gases will react with N2Gas-generating gas-phase reaction to form Si3N4This Si3N4Directly on pre-crystallized Si3N4Nucleation and directional growth of crystal grains, and in-situ growth of Si by gas-solid mechanism3N4A whisker. The Si/N/C powder is also the main raw material of the high-performance structural ceramic, has lower cost and a small amount of market supply, and is easy to synthesize artificially. The crystal whisker synthesized by the method has high purity and crystal whisker [ O]]＜1wt％，[C]Less than 0.01 wt%, the prepared whisker is pure flocculent, the whisker length is 0.05-5 mm, the diameter is 0.1-1 μm, and the whisker is generally α phases.
FIG. 1 shows Si/N/C powder synthesis of Si3N4A schematic diagram of a whisker apparatus;
FIG. 2(a) shows carbothermic synthesis of Si3N4Schematic diagram of whisker growth principle;
FIG. 2(b) shows Si/N/C in situ synthesis of Si3N4Schematic diagram of whisker growth principle;
FIG. 3 is Si/N/C in situ synthesis of Si3N4X-ray diffraction patterns of (a);
FIG. 4 is Si/N/C in situ synthesis of Si3N4The shape of the whisker.
Examples
5gSiN0.5C1.2Amorphous powder (1), particle size 10nm, surface O: 5 wt% into BN crucible (2), as shown in FIG. 1, placing crucible (2) into graphite furnace (3), and evacuating to 10%-3Charging 1atm of high purity (>99.999 wt%) nitrogen at torr. Heating to 1600 deg.C, maintaining for 1 hr, and naturally cooling to room temperature to obtain product with length of 0.1-5 mm and diameter of 0.1-0.5 μ, [ O]]：0.8wt％，[C]: 0.05 wt% pure white flocculent Si3N4Whisker (4) being α -Si3N4. The whisker morphology is shown in fig. 4, and the x-ray diffraction is shown in fig. 3. The use of BN crucible is an important link to ensure the high purity of whisker, because the whisker grows according to V-S, the head of the crystal is smooth and has no impurity ball drop, and the method and the carbon thermal method are schematically shown in figure 2 for comparison.
Comparative example
The procedure of synthesis was the same as in example 1, and when the conditions were changed as follows, no whisker was formed (1) andthe forming temperature is 1400 ℃; (2) the synthesis temperature is 1900 ℃; (3)1atm Ar, 1600 ℃; (4) raw material SiN0.01C1.2(ii) a (5) Raw material SiN1.3。
The invention has the advantages of low cost of raw materials, simple synthesis process, high purity of products, no need of subsequent treatment, dependence of yield on melting amount of a crucible and a furnace, commercial production conditions, and application of the prepared crystal whisker as an ideal toughening element.
Claims (3)
1. Preparation of Si3N4A method of whisker, characterized in that: Si/N/C powder is used as raw material and is pyrolyzed under nitrogen atmosphere to form Si3N4Whisker; the powder is composed of SiN0.5C1.2And pyrolysis synthesis temperature: 1500-1900 ℃, the time is 0.5-4 h, and the gas pressure is as follows: 0.5 to 2 atm.
2. Preparation of Si as claimed in claim 13N4A method of whiskers characterized byThe pyrolysis synthesis temperature is 1600-1800 ℃.
3. Preparation of Si as claimed in claim 13N4A method for producing whiskers, characterized in that a BN crucible is used for the pyrolysis.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94110355A CN1055324C (en) | 1994-06-30 | 1994-06-30 | Amorphous in-situ synthesized nm silicon nitride crystal whisker |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94110355A CN1055324C (en) | 1994-06-30 | 1994-06-30 | Amorphous in-situ synthesized nm silicon nitride crystal whisker |
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| Publication Number | Publication Date |
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| CN1114368A CN1114368A (en) | 1996-01-03 |
| CN1055324C true CN1055324C (en) | 2000-08-09 |
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| CN94110355A Expired - Fee Related CN1055324C (en) | 1994-06-30 | 1994-06-30 | Amorphous in-situ synthesized nm silicon nitride crystal whisker |
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| CN101224877B (en) * | 2008-01-28 | 2011-04-20 | 哈尔滨工业大学 | Method for preparing silicon nitride nano-wire |
| CN101550600B (en) * | 2009-04-22 | 2011-05-25 | 中国地质大学（北京） | A method to prepare a high-purity high-density monocrystalline silicon nitride nano array |
| CN106283137B (en) * | 2016-08-25 | 2018-03-02 | 山东清大银光金属海绵新材料有限责任公司 | Silicon nitride crystal whisker strengthens the preparation of sponge structure sections chrome molybdenum hafnium alloy damping material |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1052652A (en) * | 1991-02-04 | 1991-07-03 | 冶金工业部钢铁研究总院 | Making method of crystal whisker excess weld metal silicon nitride compound material |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1052652A (en) * | 1991-02-04 | 1991-07-03 | 冶金工业部钢铁研究总院 | Making method of crystal whisker excess weld metal silicon nitride compound material |
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| CN1114368A (en) | 1996-01-03 |
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