CN102485645B - Method for rapidly combusting and synthesizing silicon nitride powder by using foaming agent capable of producing nitrogen while decomposing as additive - Google Patents
Method for rapidly combusting and synthesizing silicon nitride powder by using foaming agent capable of producing nitrogen while decomposing as additive Download PDFInfo
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- CN102485645B CN102485645B CN 201010570236 CN201010570236A CN102485645B CN 102485645 B CN102485645 B CN 102485645B CN 201010570236 CN201010570236 CN 201010570236 CN 201010570236 A CN201010570236 A CN 201010570236A CN 102485645 B CN102485645 B CN 102485645B
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Abstract
The invention discloses a method for rapidly combusting and synthesizing silicon nitride powder by using a foaming agent capable of producing nitrogen while decomposing as an additive, which comprises the following steps: in the rapid combustion and synthesis process of silicon nitride, the foaming agent capable of producing nitrogen while decomposing is taken as an auxiliary agent; the foaming agent possesses the purity greater than 99% and comprises an azo compound, a nitroso compound, a sulfohydrazide compound and the like. The method of the invention has the following beneficial effects: 1) the used foaming agent has the advantages of no toxicity, constant color, no odor, no pollution and insolubility in common solvents; 2) the foaming agent of the invention has the advantages of high gas evolution, small particles and good dispersibility; 3) the foaming agent is selected as nitrogen source, so that production security is increased, and the raw material cost is reduced; and 4) the foaming agent discharges a lot of heat while decomposing, so that the combustion and synthesis reaction can be carried out with a faster reaction rate, the instability problem during the combustion process can be solved.
Description
Technical field
The present invention relates to the method for burning synthetic (claiming that also self propagating high temperature is synthetic) beta-silicon nitride powder, particularly can produce the whipping agent of nitrogen as the method for additive rapid combustion synthesizing silicon nitride powder when decomposing, belong to the preparing technical field of beta-silicon nitride powder.
Background technology
Silicon nitride ceramics is the Typical Representative of advanced structural ceramic material, can be widely used in the fields such as machinery, chemical industry, space flight and aviation because it has excellent high-temperature mechanics, thermal property and chemical stability.Alpha-silicon nitride powders is as the starting material of producing silicon nitride ceramics, and its high price has seriously limited consumption and the scale of silicon nitride ceramics.Therefore, low-cost alpha-silicon nitride powders preparation technology's research and development seem particularly necessary.
The preparation method of the beta-silicon nitride powder of having researched and developed at present has a lot, wherein representative comprising: silica flour direct nitridation method, carbothermic method, silicon imide decomposition method, plasma method and combustion synthesis method.The Denka etc. of the Stark of some large-scale manufacturers such as Germany, Japan generally adopts direct nitridation method to prepare beta-silicon nitride powder in the world.Its subject matter is to reach 72 hours the production cycle, needs secondary nitrogenize and energy consumption large.Equally, also there are the shortcomings such as production cycle length, complex technical process, production cost height in carbothermic method technique; In product, the foreign matter contents such as carbon, oxygen are also higher in addition.Japan UBE company adopts the silicon imide decomposition method to produce commercialized degree beta-silicon nitride powder preferably; The shortcoming that this method exists has: complex process, production cost are high, easily produce etching problem in production process, and the cl content in product is higher.Plasma method is produced beta-silicon nitride powder and is also had the shortcomings such as equipment is complicated, cost is high, energy consumption is large; And do not possess the possibility that forms extensive industry on product price and production scale yet.Comparatively speaking, by synthetic (the Combustion Synthesis of the burning of USSR (Union of Soviet Socialist Republics) scientist invention, CS) technology has the advantages such as energy-conservation, that product purity is high, synthesis cycle is short, it is typical low-cost technology of preparing, with synthesizing silicon nitride powder, be expected to the decrease cost, thereby the silicon nitride ceramics large-scale application is played the promoting technology effect.
After the eighties in 20th century, investigation of materials person has carried out a large amount of reports to adopting combustion synthesis technology to prepare beta-silicon nitride powder both at home and abroad.The rate firsts to file such as Russian scientist Merzhanov name be called the patent of " preparation method with high α phase content silicon nitride " (U.S. Patent number US5032370); But the combustion synthesis reaction gaseous tension that uses in this patent is up to 30 MPa, causes production security relatively poor; In addition, the ammonium salt amount of adding in reaction raw materials be up to add 60 wt% of silica flour content, make clean productive rate not high; Moreover the Si powder raw material also needs to carry out pre-treatment through special methods such as hydrofluoric acid, has used amorphous Si or the silicon imide of different content, has caused the raw materials cost increase.The name of the inventions such as Holt J. Birch is called " burning synthetic thin brilliant α phase silicon nitride " (U.S. Patent number US4944930), has adopted 50% the high malicious explosive material NaN that accounts for reactant
3Deng being nitrogenous source, not only can introduce impurity, also be not suitable for safety in production simultaneously.Chinese patent application number is 01126400.4 to disclose " the synthetic method that prepare beta-silicon nitride whisker of self propagating high temperature ", and the method adopts oxide compound to make the auxiliary agent of growing.Chinese patent application number is 200410017913.0 to disclose name and be called " brilliant as the standby beta-silicon nitride rod of growth auxiliary agent burning synthesis for preparing with silicon nitride magnesium ", and the method adopts silicon nitride magnesium to make auxiliary agent.Aforementioned two Chinese patent application are all inevitably introduced oxygen or metallic impurity in product.In a word: prepare beta-silicon nitride powder with traditional combustion synthesis process and have following defective: 1) clean productive rate is low; 2) synthetic cost is high; 3) technological process is unstable; 4) easily introduce impurity in product.This makes and currently still is difficult to adopt combustion synthesis process to prepare on a large scale beta-silicon nitride powder.
Summary of the invention
The technical problem to be solved in the present invention is to provide and a kind ofly can produces the whipping agent of nitrogen as the method for additive rapid combustion synthesizing silicon nitride powder when decomposing; The clean productive rate of the method is high, synthetic cost is low, stable technical process and can not introduce impurity.
For solving the problems of the technologies described above, the present invention adopts following technical scheme:
A kind ofly can produce the whipping agent of nitrogen as the method for additive rapid combustion synthesizing silicon nitride powder when decomposing, comprise the steps: in rapid combustion synthesizing silicon nitride powder process, can produce the whipping agent of nitrogen as the additive in reaction process during with decomposition.
The whipping agent that further, can produce nitrogen during described decompose comprises one or more the mixture in azo-compound, nitroso compound or sulfonyl hydrazines compound.
Further, the whipping agent that can produce nitrogen during described decompose be Cellmic C 121 (be called for short: the AC whipping agent) or Diisopropyl azodicarboxylate (be called for short: the AIBN whipping agent) or 2,2'-Azobis(2,4-dimethylvaleronitrile) the ABVN whipping agent) or N (be called for short:, N'-dinitrosopentamethlyene tetramine (be called for short: the DPT whipping agent) or p-toluene sulfonyl hydrazide (be called for short: the TSH whipping agent) or benzol sulfohydrazide (be called for short: the BSH whipping agent) or 4,4'-OBSH the OBSH whipping agent) etc. (be called for short: the mixture of one or more in.
Further, can produce the purity of the whipping agent of nitrogen＞99% during described decompose.
Further, a kind ofly can produce the whipping agent of nitrogen as the method for additive rapid combustion synthesizing silicon nitride powder when decomposing, comprise the steps:
1) preparation of reagent
By silica flour: alpha-silicon nitride powders: the weight ratio that can produce the whipping agent of nitrogen during decomposition is that 35 ~ 90:0 ~ 50:1 ~ 40 take raw material and fully mix, the preparation reagent;
2) pre-treatment of reagent
The mixed material of step 1) is placed on grinding plant grinds, the mixture after grinding sieves, and is loaded in container;
3) combustion synthesis reaction
With step 2) in the high pressure reaction assembly put into of container, vacuumize; Be filled with nitrogen in high pressure reaction assembly, then cause combustion synthesis reaction by local electric ignition type of heating;
4) aftertreatment
After the step 3) reaction finished, the synthetic product that obtains of furnace cooling burning dropped to the pressure in reactor normal atmosphere and unloads sintetics; The clean surface layer is removed the not part of complete reaction; The silicon nitride product of preparation is carried out fragmentation and stage treatment, namely obtain the beta-silicon nitride powder of homogeneous.
Further, the relative density after described step 2), mixture sieves is 25～70%; On the one hand, make between powder granule distance be unlikely to far away, combustion reactions is difficult to keep; On the other hand, make between powder granule distance be unlikely near, nitrogen is difficult to infiltration.
Further, described step 3) mesohigh reaction unit is with cooling water jecket, and its role is cooling reaction unit, and silicon powder nitride combustion reactions liberated heat can in time be derived, and the envrionment temperature in reaction unit is effectively controlled.
Further, the original pressure that is filled with in described step 3) after nitrogen is 0.5 ~ 5 MPa, and the silicon powder nitride combustion reactions can be kept.
The present invention has following beneficial effect:
1) that the whipping agent that can produce nitrogen when decomposing that adopts in the present invention has is nontoxic, nondiscoloration, odorless, do not pollute, and is insoluble to the advantage of common solvent;
The whipping agent gas forming amount that can produce nitrogen during 2) with decomposition is high, and particle is little, good dispersity, and to discharge nitrogen as main, be difficult for overflowing from foam;
3) adopt the whipping agent that can produce nitrogen when decomposing to make nitrogenous source, take for the synthetic additive of silicon powder nitride burning, can reduce on the one hand the required nitrogen pressure of combustion synthesis reaction, thereby be conducive to increase production security; On the other hand, can reduce nitrogen use level, thereby be conducive to reduce raw materials cost;
The whipping agent that 4) can produce nitrogen when decomposing can be emitted amount of heat when decomposing, combustion synthesis reaction is carried out with speed of reaction faster, is conducive to solve the instability problem of combustion processes;
In sum: method provided by the invention is conducive to reduce the production cost of beta-silicon nitride powder, stability and the production security of increase combustion synthesis process, and can further enhances productivity.
Description of drawings
Fig. 1 is the X ray diffracting spectrum of combustion synthesized product in the embodiment of the present invention 1 ~ 5.
Embodiment
Embodiment 1
A kind ofly can produce the whipping agent of nitrogen as the method for additive rapid combustion synthesizing silicon nitride powder when decomposing, comprise the steps:
1) by silica flour: alpha-silicon nitride powders: the weight ratio of the AC whipping agent of purity＞99% is to take raw material at 49.5: 49.5: 1;
2) raw material for preparing was placed on oscillating mill mixed grinding 1 hour, after grinding powder through sieving,, control making powder blank relative density is 40%, in the container of then packing into;
3) container is put into combustion synthesis reaction device with cooling water jecket, laid helical tungsten filamen and titanium valve is done ignition source at an end of powder base; After vacuumizing, be filled with nitrogen in the combustion synthesis reaction device, until pressure reaches 2 MPa; Energising adds the thermal ignition titanium valve to tungsten filament, brings out powder systems generation combustion synthesis reaction;
4) after question response finishes, the synthetic product that obtains of furnace cooling burning, drop to the pressure in reactor normal atmosphere and unload sintetics; The clean surface layer is removed imperfect combustion part; The silicon nitride product of preparation is carried out fragmentation and stage treatment, obtain homogeneous purity 99% beta-silicon nitride powder.
The X ray diffracting spectrum of product is as shown in Fig. 11, and the powder of gained is take beta phase silicon nitride as principal phase, and contents of free si is 0.07%.
Embodiment 2
A kind ofly can produce the whipping agent of nitrogen as the method for additive rapid combustion synthesizing silicon nitride powder when decomposing, comprise the steps:
1) by silica flour: the weight ratio of the AC whipping agent of purity＞99% is that 90:10 takes raw material;
2) raw material for preparing was placed on oscillating mill mixed grinding 1.5 hours, after grinding, powder is processed through screening, and control making powder blank relative density is 40%, in the container of then packing into;
3) container is put into combustion synthesis reaction device with cooling water jecket, laid helical tungsten filamen and titanium valve is done ignition source at an end of powder base; After vacuumizing, be filled with nitrogen in the combustion synthesis reaction device, until pressure reaches 4.0 MPa; Energising adds the thermal ignition titanium valve to tungsten filament, brings out powder systems generation combustion synthesis reaction;
4) after question response finishes, the synthetic product that obtains of furnace cooling burning, drop to the pressure in reactor normal atmosphere and unload sintetics; The clean surface layer is removed imperfect combustion part; The silicon nitride of preparation is carried out fragmentation and stage treatment, obtain homogeneous purity 99% beta-silicon nitride powder.
The X ray diffracting spectrum of product is as shown in Fig. 12, and mutually as principal phase, contents of free si is 0. 15% to the beta-silicon nitride powder of gained take β.
A kind ofly can produce the whipping agent of nitrogen as the method for additive rapid combustion synthesizing silicon nitride powder when decomposing, comprise the steps:
1) by silica flour: alpha-silicon nitride powders: the AC whipping agent of purity＞99%: the weight ratio of the DPT whipping agent of purity＞99% is that 47:47:3:3 takes raw material;
2) raw material for preparing was placed on oscillating mill mixed grinding 1.5 hours, after grinding, powder is processed through screening, and control making powder blank relative density is 50%, in the container of then packing into;
3) container is put into combustion synthesis reaction device with cooling water jecket, laid helical tungsten filamen and titanium valve is done ignition source at an end of powder base; After vacuumizing, be filled with nitrogen in the combustion synthesis reaction device, until pressure reaches 3 MPa; Energising adds the thermal ignition titanium valve to tungsten filament, brings out powder systems generation combustion synthesis reaction;
4) after question response finishes, the synthetic product that obtains of furnace cooling burning, drop to the pressure in reactor normal atmosphere and unload sintetics; The clean surface layer is removed imperfect combustion part; The silicon nitride of preparation is carried out fragmentation and stage treatment, obtain homogeneous purity 99% beta-silicon nitride powder.
The X ray diffracting spectrum of product is as shown in Fig. 13, and mutually as principal phase, contents of free si is 0.05% to the beta-silicon nitride powder of gained take α.
A kind ofly can produce the whipping agent of nitrogen as the method for additive rapid combustion synthesizing silicon nitride powder when decomposing, comprise the steps:
1) by silica flour: alpha-silicon nitride powders: the weight ratio of the DPT whipping agent of purity＞99% is that 40:50:10 takes raw material;
2) raw material for preparing was placed on oscillating mill mixed grinding 1.5 hours, after grinding, powder is processed through screening, and control making powder blank relative density is 35%, in the container of then packing into;
3) container is put into combustion synthesis reaction device with cooling water jecket, laid helical tungsten filamen and titanium valve is done ignition source at an end of powder base; After vacuumizing, be filled with nitrogen in the combustion synthesis reaction device, until pressure reaches 3.5 MPa; Energising adds the thermal ignition titanium valve to tungsten filament, brings out powder systems generation combustion synthesis reaction;
4) after question response finishes, the synthetic product that obtains of furnace cooling burning, drop to the pressure in reactor normal atmosphere and unload sintetics; The clean surface layer is removed imperfect combustion part; The silicon nitride of preparation is carried out fragmentation and stage treatment, obtain homogeneous purity 98% beta-silicon nitride powder.
The X ray diffracting spectrum of product is as shown in Fig. 14, and the beta-silicon nitride powder of gained mutually as principal phase, has a small amount of silicon carbide or silicon oxynitride to exist mutually take α in powder.
A kind ofly can produce the whipping agent of nitrogen as the method for additive rapid combustion synthesizing silicon nitride powder when decomposing, comprise the steps:
1) by silica flour: the AC whipping agent of purity＞99%: the DPT whipping agent of purity＞99%: the weight ratio of the p-toluene sulfonyl hydrazide whipping agent of purity＞99% is that 60:20:10:10 takes raw material;
2) raw material for preparing was placed on oscillating mill mixed grinding 1.5 hours, after grinding, powder is processed through screening, and control making powder blank relative density is 40%, in the container of then packing into;
3) container is put into combustion synthesis reaction device with cooling water jecket, laid helical tungsten filamen and titanium valve is done ignition source at an end of powder base; After vacuumizing, be filled with nitrogen in the combustion synthesis reaction device, until pressure reaches 0.5 MPa; Energising adds the thermal ignition titanium valve to tungsten filament, brings out powder systems generation combustion synthesis reaction;
4) after question response finishes, the synthetic product that obtains of furnace cooling burning, drop to the pressure in reactor normal atmosphere and unload sintetics; The clean surface layer is removed imperfect combustion part; The silicon nitride of preparation is carried out fragmentation and stage treatment, obtain homogeneous purity 99% beta-silicon nitride powder.
The X ray diffracting spectrum of product is as shown in Fig. 15, and the beta-silicon nitride powder of gained mutually as principal phase, has a small amount of silicon carbide or silicon oxynitride to exist mutually take α in powder.
Embodiment 6
Obviously, the above embodiment of the present invention is only for example of the present invention clearly is described, and is not to be restriction to embodiments of the present invention.For those of ordinary skill in the field, can also make other changes in different forms on the basis of the above description.Here can't give all embodiments exhaustive.Everyly belong to the row that apparent variation that technical scheme of the present invention extends out or change still are in protection scope of the present invention.
Claims (6)
1. one kind can produce the whipping agent of nitrogen as the method for additive rapid combustion synthesizing silicon nitride powder when decomposing, it is characterized in that, comprise the steps: in rapid combustion synthesizing silicon nitride powder process, can produce the whipping agent of nitrogen as the additive in reaction process during with decomposition; The whipping agent that can produce nitrogen during described decompose comprises one or more the mixture in azo-compound, nitroso compound, sulfonyl hydrazines compound.
2. according to claim 1ly can produce the whipping agent of nitrogen as the method for additive rapid combustion synthesizing silicon nitride powder when decomposing, it is characterized in that: the whipping agent that can produce nitrogen during described the decomposition is Cellmic C 121, Diisopropyl azodicarboxylate, 2,2'-Azobis(2,4-dimethylvaleronitrile), N, N'-dinitrosopentamethlyene tetramine, p-toluene sulfonyl hydrazide, benzol sulfohydrazide, 4, the mixture of one or more in the 4'-OBSH.
3. according to claim 1 and 2ly can produce the whipping agent of nitrogen as the method for additive rapid combustion synthesizing silicon nitride powder when decomposing, it is characterized in that: can produce the purity of the whipping agent of nitrogen＞99% during described the decomposition.
4. according to claim 1ly can produce the whipping agent of nitrogen as the method for additive rapid combustion synthesizing silicon nitride powder when decomposing, it is characterized in that, comprise the steps:
1) preparation of reagent
By silica flour: alpha-silicon nitride powders: the weight ratio that can produce the whipping agent of nitrogen during decomposition is that 35～90:0～50:1～40 take raw material and fully mix, the preparation reagent;
2) pre-treatment of reagent
The mixed material of step 1) is placed on grinding plant grinds, the mixture after grinding sieves, and is loaded in container;
3) combustion synthesis reaction
With step 2) in the high pressure reaction assembly put into of container, vacuumize; Be filled with nitrogen in high pressure reaction assembly, then cause combustion synthesis reaction by local electric ignition type of heating;
4) aftertreatment
After the step 3) reaction finished, the synthetic product that obtains of furnace cooling burning dropped to the pressure in reactor normal atmosphere and unloads sintetics; The clean surface layer is removed the not part of complete reaction; The silicon nitride product of preparation is carried out fragmentation and stage treatment, namely obtain the beta-silicon nitride powder of homogeneous.
5. according to claim 4ly can produce the whipping agent of nitrogen as the method for additive rapid combustion synthesizing silicon nitride powder when decomposing, it is characterized in that: described step 3) mesohigh reaction unit is with cooling water jecket.
6. according to claim 4ly can produce the whipping agent of nitrogen as the method for additive rapid combustion synthesizing silicon nitride powder when decomposing, it is characterized in that: the original pressure that is filled with in described step 3) after nitrogen is 0.5～5MPa.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4944930A (en) * | 1986-11-21 | 1990-07-31 | Regents Of The University Of California | Synthesis of fine-grained α-silicon nitride by a combustion process |
| CN1362358A (en) * | 2002-01-22 | 2002-08-07 | 清华大学 | Low pressure combustion process of synthesizing alpha-phase silicon nitride powder |
| CN1433959A (en) * | 2002-01-22 | 2003-08-06 | 北京科技大学 | Process for combustion synthesizing high alpha phase superfine silicon carbide powder and silicon nitride whisker |
| CN101353160A (en) * | 2008-09-09 | 2009-01-28 | 辽宁工业大学 | Synthetic method of silicon nitride nanopowder |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4944930A (en) * | 1986-11-21 | 1990-07-31 | Regents Of The University Of California | Synthesis of fine-grained α-silicon nitride by a combustion process |
| CN1362358A (en) * | 2002-01-22 | 2002-08-07 | 清华大学 | Low pressure combustion process of synthesizing alpha-phase silicon nitride powder |
| CN1433959A (en) * | 2002-01-22 | 2003-08-06 | 北京科技大学 | Process for combustion synthesizing high alpha phase superfine silicon carbide powder and silicon nitride whisker |
| CN101353160A (en) * | 2008-09-09 | 2009-01-28 | 辽宁工业大学 | Synthetic method of silicon nitride nanopowder |
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