CN101214934A - Self-combustion non-pollution fast preparation method for alpha-phase silicon nitride powder - Google Patents
Self-combustion non-pollution fast preparation method for alpha-phase silicon nitride powder Download PDFInfo
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- CN101214934A CN101214934A CNA200710114560XA CN200710114560A CN101214934A CN 101214934 A CN101214934 A CN 101214934A CN A200710114560X A CNA200710114560X A CN A200710114560XA CN 200710114560 A CN200710114560 A CN 200710114560A CN 101214934 A CN101214934 A CN 101214934A
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Abstract
The invention discloses an auto-igniting and non-pollution process for preparing quickly silicon nitride powder with high alpha phase, which is characterized in that the process comprises technical procedures of handling raw materials, batching, mixing, auto-igniting reaction and obtaining finished products, the process achieves auto-igniting compounding alpha phase silicon nitride powder by employing non-toxicity and anacidity addition agent. The inventory process has the advantages of reducing environmental pollution, improving protection for operators. The prepared powder body includes higher alpha phase and has perfect sintering activity. The whole procedure is simple and dependable, and the mass production is easily achieved.
Description
Technical field:
The invention belongs to field of inorganic nonmetallic material, be specifically related to a kind of method that adopts self-combustion non-pollution to prepare alpha-phase silicon nitride powder fast, the silicon nitride of preparation can be widely used in fields such as fine ceramics and high-end refractory materials.
Background technology:
Because silicon nitride (Si
3N
4) pottery has unique physical and mechanical property,, high strength low such as density, high rigidity, wear-resistant, corrosion-resistant, good heat endurance (particularly low thermal coefficient of expansion), high thermal conductivity etc. have a wide range of applications in fields such as Aeronautics and Astronautics, semiconductor, electronics, chemical industry, the energy, machine-building, weapon industries.But the manufacturing cost of silicon nitride ceramics is higher at present, and major cause is because wherein nitride ceramics powder body material cost is too high, thereby silicon nitride ceramics can not get applying widely.
Silicon nitride is typical covalent bond compound, two kinds of crystal formations are arranged, β is acicular crystals mutually, belongs to high-temperature stable, α phase crystalline particulate body, belong to the low-temperature stabilization type, both are hexagonal crystal system, and the internal strain of α phase structure is mutually bigger than β, so free energy is mutually higher than β, at 1400-1600 ℃ of heating, α-Si
3N
4Can be transformed into β-Si
3N
4The transformation of α → β phase generally can take place in the sintering process of beta-silicon nitride powder, this phase transformation is separated out mechanism by dissolving and is carried out, simultaneous density is densified, the sintering character of alpha silicon nitride will be far superior to the beta silicon nitride powder, and the beta-silicon nitride powder that therefore how to prepare high α phase content is the study hotspot in this field always.
The traditional method of preparation α phase silicon nitride powder can be divided into following several, and first kind is metallic silicon power (Si) direct nitridation method of industrial extensive employing, and second kind is silicon-dioxide (SiO
2) carbothermic method, the third is a chemical gas phase synthetic method, and the 4th kind is relatively advanced plasma (orifice) gas phase synthesi, and the 5th kind is from climing combustion high-temperature synthesis.
The metallic silicon power direct nitridation method is: in the atmosphere of nitrogen or ammonia, the heating of metal silica flour makes it to take place nitrogenizing reaction in electric furnace, this method is simple, and be the most effective of synthetic alpha silicon nitride powder and be relative simple method, be the method for widespread usage in the industry.But this method has its obvious shortcoming, silica flour may melt in pyroreaction, cause reaction atmosphere diffusion difficulty, secondly along with the carrying out that reacts, the silicon nitride layer that coats silica flour can stop the further nitrogenize of inner silica flour, in addition, whole course of reaction needs twice nitrogenize, need a couple of days this reaction time, must strictly control reaction temperature from start to finish in this process, nitrogen partial pressure guarantees to generate the thermal environment that α needs mutually with gas flow, has caused the bigger energy resource consumption of these method needs, synthetic powder granularity skewness, impurity content is higher, can't satisfy preparation high-performance Si
3N
4The ingredient requirement of pottery.
The silica carbothermic method is that SiO 2 powder is fully mixed with carbon dust, utilizes carbon reduction SiO under the nitrogen atmosphere that flows
2, the Si that is reduced out and SiO and nitrogen further react and generate Si
3N
4, this method has that equipment is simple, cost of material is low, and the alpha-silicon nitride powders of generation has high α phase, and residual C can remove through 600 ℃ of calcinings, and powder need not the characteristics such as ball milling.But this method need add excessive carbon to guarantee SiO
2Complete reaction, the SiO that pilot process produced causes the loss of raw material easily, simultaneously at SiO
2-C-N
2Reaction system speed of response when low temperature is slow; And when high temperature, may cause generating silicon carbide, directly have influence on the productive rate and the purity of silicon nitride.
Chemical gas phase synthetic method is that siliceous compound is (such as SiH
4, SiCl
4) and the raw material of nitrogen or ammonia interfacial reaction takes place in reactor generates Si (NH
2)
2, NH is removed in washing then
4Behind the Cl this product is heated to 1200 ℃ and generates the amorphous phase silicon nitride, be heated to again and generate the alpha silicon nitride powder more than 1500 ℃, the standby beta-silicon nitride powder of this legal system has high α phase purity, characteristics that sintering activity is good, UBE (many light company of the space section) company of Japan adopts the synthetic beta-silicon nitride powder of this method to occupy high-end beta-silicon nitride powder market always, but this powder has raw material costliness, complex equipment, shortcoming that energy consumption is bigger.
Plasma method is to use direct current-arc plasma generator or high-frequency plasma generator to produce plasma, silica flour or gas-phase silicon source are transported in the plasma torch district, in the high-temperature region of temperature up to more than 10,000 degree, powder melts volatilization immediately, becomes Si with the rapid chemical combination of nitrogen
3N
4The method of powder.Silicon grain nearly all in plasma generator all is in high-octane state, reacts with very high speed and nitrogen, thus the effective Reaction time shorten of this method energy, the Si that is synthesized
3N
4Powder mostly is amorphous phase, contains higher oxygen, has higher chemism and good sintering activity, therefore need to take certain safeguard procedures in preparation and storage process, and the shortcoming of this method is the energy consumption height, complex equipment, production cost costliness.
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 in a single day reactant is 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, be a kind of method of the synthetic powder that receives much attention, it is simple to have technology, and energy consumption is low, the product purity height, the characteristics of less investment.With from climing combustion high temperature synthesizing silicon nitride ceramic powder purity height, fillibility is good, and stable performance is with low cost.
Prepare aspect the beta-silicon nitride powder adopting from climing combustion synthetic technology, existing a large amount of patents and research paper report, these results respectively have relative merits.Nitrogen pressure higher (6-30MPa) as " a kind of method for preparing alpha-phase silicon nitride " (the patent US5032370) of inventions such as Merzhanov, " preparing silicon nitride " (patent RU2257338) and " improving beta-silicon nitride powder α technology mutually " (patent RU2149824) needs from climing burning method from climing combustion, to the equipment requirements harshness, be unfavorable for scale operation, a large amount of ammonia salt that contains Cl, F of Cai Yonging simultaneously, can produce a large amount of HCl, HF gas after the reaction, to the seriously corroded of equipment, simultaneously operator have been brought bigger actual bodily harm; There is same problem in " method of the synthetic α phase silicon nitride powder of temperature control activation self-propagating combustion " (the patent CN1673070A) of people such as the Lin Zhiming of Physical Chemistry Technology Inst., Chinese Academy of Sciences invention; The Chen Ke of Tsing-Hua University newly waits the suspension nitrogenize technology of the silica flour of people's invention " method of the synthetic alpha-phase silicon nitride powder of a kind of low-pressure combustion " (patent CN1362358A) employing, the following step of main branch is finished: 1. pair silica flour carries out pickling and ultrasonic pretreatment, 2. add promoting agent, thinner and additive, 3. the pellet that mixes was ground 15-30 hour, 3. the material behind the ball milling is 50～70 ℃ of oven dry, put into reactor, be blown into the nitrogen of 0.1-1MPa after vacuumizing from the powder bottom, bring out material combusting simultaneously.Though this method can reduce nitrogen gas pressure, whole operation is various and consuming time, and the production cycle is long, introduces other impurity easily, and energy consumption is relatively large, has driven the raising of whole production cost; People's such as the Ge Changchun of University of Science ﹠ Technology, Beijing " with the method for combustion synthesizing high alpha phase superfine beta-silicon nitride powder and silicon nitride crystal whisker " (patent CN1433959A) adopts and adds CaF
2, caused the Ca content of synthetic back powder to increase, influence the use properties of powder; People's such as the Ge Changchun of University of Science ﹠ Technology, Beijing " a kind of method of synthesizing isotropic silicon nitride powder adopting layer type material-distribution " (patent CN179995A), raw material ground and mixed and drying step are consuming time loaded down with trivial details, and the stratiform cloth is consuming time, is unfavorable for large-scale production; There is HCl in people's such as the Yang Jun of Physical Chemistry Technology Inst., Chinese Academy of Sciences " method of the synthetic α phase silicon nitride powder of controlled temperature combustion " (patent CN1696076A) in the reacted tail gas, still fail to solve preferably the safety in production problem to operator; Above patent lays particular emphasis on and improves α phase silicon nitride content in the combustion synthesized product, and the existence of HF, HCl is to operator's body and mind injury problem when not considering scale operation.
Summary of the invention:
The objective of the invention is to overcome the deficiency of above-mentioned prior art, and the method that provides a kind of self-combustion non-pollution to prepare alpha-phase silicon nitride powder fast overcomes toxic, acid additives (employing NH that prior art generally adopts
4Cl, NH
4F is as additive; after finishing, reaction contains HCl, HF in the waste gas; contaminate environment, harmful) shortcoming, provide a kind of and realized method from the synthetic α phase silicon nitride powder of climing combustion with nontoxicity, no acidic additive; reduce environmental pollution; raising is to operator's protection, and the powder of preparation contains higher α phase, and sintering activity is good; whole operation is simple and reliable, is easy to realize scale operation.
In order to achieve the above object, the present invention is achieved in that self-combustion non-pollution prepares the method for alpha-phase silicon nitride powder fast, and its special character is that it comprises the steps:
(1) raw material is processed: be that 100-300 purpose metallic silicon power carried out the high speed ball-milling treatment 12-16 hour to granularity, improve the activity of silica flour, wherein the purity of silica flour is greater than 99.5%, silica flour is done mixed through mechanization, namely adopt any in high energy ball mill or the planetary ball mill, be placed in the cylinder of steel, with Si
3N
4A kind of or mixing in ball, the steel ball is as ball-milling medium;
(2) batching: with the metallic silicon power after the above-mentioned processing is raw material, adds thinner, additive, and its weight percent is:
Metallic silicon power (handling the back): 30-45wt%,
Thinner 35-50wt%,
Additive 5-20wt%,
Above-mentioned diluent can be alpha silicon nitride powder synthetic from climing combustion or that additive method is synthetic, the α phase content of α phase silicon nitride powder＞92%, and average grain diameter is 0.3-20 μ m, additive is (NH
4)
2CO
3, (NH
4) HCO
3, CO (NH
2)
2In any one or any two kinds and two or more combination;
(3) mix: the mixture of batching step was stirred 1-4 hour, it is fully mixed, sieves with the 40-60 eye mesh screen after taking out, described stirring is that mechanization is done and mixed, namely adopt in agitating ball mill, the jar mill any, with Si
3N
4A kind of in ball, the steel ball or be mixed into ball-milling medium, material: the ball weight ratio is 1: 2～5, the material after mixed is crossed the 40-60 eye mesh screen;
(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 4-8MPa, igniting guiding high temperature is synthetic from climing combustion, can be wound in spirrillum by the nichrome wire (or tungsten) of 0.6mm, feed the direct current of 10-40A, time length 4～15s makes 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, finishes until building-up reactions, the logical recirculated water cooling of synthetic post-reactor;
(5) get finished product: reaction post-reactor internal pressure can reduce, and when the pressure of reactor drops to 5-7MPa, finishes from climing combustion reaction, and the pressure in the releasing reactor fills 1-5 minute ordinary nitrogen or air to reactor, eliminates remaining small amount of N H
3, the block product that obtains loosening obtains the alpha-phase silicon nitride powder finished product after the fine grinding.
Self-combustion non-pollution of the present invention prepares the method for alpha-phase silicon nitride powder fast, has realized pollution-freely preparing alpha-phase silicon nitride powder from climing combustion, has overcome to contain HCl, HF in the combustion synthesis method gas and contain F
-The problem of salt has solved environmental pollution and the problem harmful to operating personnel's body and mind, the product purity height that obtains, α phase content height.By design and adjustment reactant system, with (NH
4)
2CO
3, (NH
4) HCO
3And CO (NH
2)
2Substitute the ammonia salt that contains Cl, F etc. avirulence, acid additives; Control simultaneously maximum combustion temperature and obtain high α phase, the silica flour of ball milling has improved initial combustion combustion reactant activity for reaction provides a small amount of amorphous silica powder, and reaction (1100 ℃-1500 ℃) under lower temperature can be carried out; Select suitable additive, the control reaction obtains high α phase in suitable temperature range; Add a certain amount of Si
3N
4Powder, control on the one hand the temperature of reaction, the uniform temperature fields at each position of control reaction mass system distributes, prevented the generation of too much β phase, adjusted simultaneously the porosity of material, 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 that self-combustion non-pollution of the present invention prepares alpha-phase silicon nitride powder fast 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) do not contain HCl, HF and contain F in the gas after the reaction
-Salt, environmentally friendly, operating personnel's body and mind there is not impact, convenient operation;
5) because temperature and reaction speed when having controlled preferably reaction, the conversion ratio height of reaction, synthetic product purity height, α phase content height (up to more than 96%), the crystal grain rule is convenient to grind post processing.
Description of drawings:
Fig. 1 is the beta-silicon nitride powder scanning electron microscope microscopic analysis figure of embodiment 1 from climing combustion synthetic product sampling;
Fig. 2 is that embodiment 1 is from the beta-silicon nitride powder X-ray diffractogram of climing combustion synthetic product sampling;
Fig. 3 is that embodiment 2 is from the beta-silicon nitride powder ESEM microscopic analysis figure of climing combustion synthetic product sampling;
Fig. 4 is that embodiment 2 is from the beta-silicon nitride powder X-ray diffractogram of climing combustion synthetic product sampling;
Fig. 5 is that embodiment 3 is from the beta-silicon nitride powder ESEM microscopic analysis figure of climing combustion synthetic product sampling;
Fig. 6 is that embodiment 3 is from the beta-silicon nitride powder X-ray diffractogram of climing combustion synthetic product sampling;
Fig. 7 is that embodiment 4 is from the beta-silicon nitride powder ESEM microscopic analysis figure of climing combustion synthetic product sampling;
Fig. 8 is that embodiment 4 is from the beta-silicon nitride powder X-ray diffractogram of climing combustion synthetic product sampling;
Embodiment:
For Comprehension and Implementation better, describe the method that self-combustion non-pollution of the present invention prepares alpha-phase silicon nitride powder fast in detail below in conjunction with embodiment.
Embodiment 1, with 100 purpose metallic silicon powers, and purity＞99.5%, iron level＜0.2% 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.Silica flour behind the ball milling is as the raw material of next step batch mixing.Silica flour (behind the ball milling) is that 45% (in the present embodiment, weight is 900 grams), silicon nitride are 50% (in the present embodiment, weight is 1000 grams for average grain diameter 20 μ m, α phase＞94%), (NH by weight
4) HCO
3After 5% (in the present embodiment, weight is 100 grams) mixed, with Si
3N
4Ball is ball-milling medium, be placed in the corundum tank, material: the ball weight ratio is 1: 2, be placed on the agitating ball 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, be filled with the high pure nitrogen of 8MPa, make heater with the nickel filament of diameter 0.6mm, pass into 40 amperes electric current, duration 4s makes coil heating, and temperature has reached the reaction temperature of silica flour and nitrogen in the raw mix, chemical reaction mode with climing combustion in material successively advances then, reaction time continues 18 minutes, and reactor pressure begins to descend, the logical circulating water of reactor this moment, when the pressure of reactor drops to 7MPa, pressure in the releasing reactor, nothing contains F in the waste gas of release, the air release of Cl fills 1 minute ordinary nitrogen to reactor, eliminates remaining a small amount of NH
3Open then the product that reactor takes out loose shape, remove the unreacted silica flour of surperficial one deck, the product integral body that obtains is milk yellow, product weight reached 2460 the gram, the alpha-phase silicon nitride purity that obtains after the fine grinding greater than 98.8%, α phase content greater than 94%, contents of free si is less than 0.15%, reaction yield＞95%.
The ESEM microscopic analysis shape appearance figure of synthetic product is seen Fig. 1 in this example, and X-ray diffraction analysis figure sees Fig. 2.Adopt the X-ray diffraction analysis standard measure to calculate its α and be mutually 94.3wt%, contents of free si is 0.12wt%.The oxygen level of powder is 1.21wt%, and nitrogen content is greater than 38.8%.
Embodiment 2, and with 300 purpose metallic silicon powers, purity＞99.5% is with Si
3N
4Ball is ball-milling medium, is placed in the cylinder of steel, and material: the ball weight ratio is 1: 5, carries out 12 hours ball-milling treatment at high energy ball mill.Silica flour (behind the ball milling) is 30% (in the present embodiment, weight is 600 grams), silicon nitride 50% (in the present embodiment, weight is 1000 grams for average grain diameter 0.3 μ m, α phase＞94%), (NH by weight
4)
2 CO
320% (in the present embodiment, weight is 400 grams) mix after, take steel ball as ball-milling medium, be placed in the corundum tank, material: the ball weight ratio is 1: 5, puts on the jar mill stirring ball-milling 4 hours, material after mixing is crossed 60 eye mesh screens, material after sieving is positioned in the half-terete graphite boat of porous uniformly, puts into then from climing combustion synthesis reactor, after vacuumizing, be filled with the high pure nitrogen of 4MPa, nickel filament with diameter 0.6mm is made heater, passes into 10 amperes electric current, duration 15s, make coil heating, temperature has reached the reaction temperature of silica flour and nitrogen in the raw mix, and chemical reaction mode with climing combustion in material successively advances then, and the reaction time continues after 25 minutes, reactor pressure begins to descend, reactor leads to circulating water, when the pressure of reactor drops to 5MPa, finishes from climing combustion reaction, pressure in the releasing reactor, do not have in the waste gas that discharges and contain F, the gas of Cl fills 5 minutes air to reactor, eliminates remaining a small amount of NH
3, open then the product that reactor takes out loose shape, remove the unreacted silica flour of surperficial one deck, the product integral body that obtains is milk yellow, and product weight has reached 1970 grams, and the silicon nitride purity that obtains after the fine grinding is greater than 98.8%, reaction yield＞96%.
The ESEM microscopic analysis shape appearance figure of synthetic product is seen Fig. 3 in this example, and X-ray diffraction analysis figure sees Fig. 4.Adopt the X-ray diffraction analysis standard measure to calculate its α and be mutually 98.2wt%, contents of free si is 0.08wt%.The oxygen level of powder is 1.40wt%, and nitrogen content is greater than 38.8%.
Embodiment 3, and with 200 purpose metallic silicon powers, purity＞99.5% is with Si
3N
4Mixing (weight ratio 1: 1) with steel ball is ball-milling medium, is placed in the cylinder of steel, and material: the ball weight ratio is 1: 5, carries out 14 hours ball-milling treatment at high energy ball mill.Silica flour (behind the ball milling) is 45% (in the present embodiment, weight is 900 grams), silicon nitride 35% (in the present embodiment, weight is 700 grams for average grain diameter 10 μ m, α phase＞94%), (NH by weight
4)
2CO
3And CO (NH
2)
220% (in the present embodiment, (NH
4)
2CO
3Be 200 grams, CO (NH
2)
2Be 200 grams) mix after, with steel ball and Si
3N
4Ball (weight ratio is 1: 1) is ball-milling medium, be placed in the corundum tank, material: the ball weight ratio is 1: 5, put 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, puts into then from climing combustion synthesis reactor, after vacuumizing, be filled with the high pure nitrogen of 7MPa, nickel filament with diameter 0.6mm is made heater, passes into 15 amperes electric current, duration 10s, make coil heating, temperature has reached the reaction temperature of silica flour and nitrogen in the raw mix, and chemical reaction mode with climing combustion in material successively advances then, and the reaction time continues after 15 minutes, reactor pressure begins to descend, reactor leads to circulating water, when the pressure of reactor drops to 6.5MPa, finishes from climing combustion reaction, pressure in the releasing reactor, do not have in the waste gas that discharges and contain F, the gas of Cl fills 3 minutes air to reactor, eliminates remaining a small amount of NH
3, open then the product that reactor takes out loose shape, remove the unreacted silica flour of surperficial one deck, the product integral body that obtains is milk yellow, and product weight has reached 2140 grams, and the silicon nitride purity that obtains after the fine grinding is greater than 98.8%, reaction yield＞95%.
The ESEM microscopic analysis shape appearance figure of synthetic product is seen Fig. 5 in this example, and X-ray diffraction analysis figure sees Fig. 6.Adopt the X-ray diffraction analysis standard measure to calculate its α and be mutually 96.9wt%, contents of free si is 0.10wt%.The oxygen level of powder is 1.38wt%, and nitrogen content is greater than 38.8%.
Embodiment 4, and with 120 purpose metallic silicon powers, purity＞99.5% is with Si
3N
4Mixing (weight ratio 2: 1) with steel ball is ball-milling medium, is placed in the cylinder of steel, and material: the ball weight ratio is 1: 4, carries out 15 hours ball-milling treatment at high energy ball mill.Silica flour (behind the ball milling) is 40% (in the present embodiment, weight is 800 grams), silicon nitride 45% (in the present embodiment, weight is 900 grams for average grain diameter 7 μ m, α phase＞94%), (NH by weight
4)
2CO
3, (NH
4) HCO
3, CO (NH
2)
2Amount to 15% (in the present embodiment, (NH
4)
2CO
3Be 100 grams, (NH
4) HCO
3Be 100 grams, CO (NH
2)
2Be 100 grams, gross weight is 300 grams) mix after, with steel ball and Si
3N
4Ball (weight ratio is 1: 1) is ball-milling medium, be placed in the corundum tank, material: the ball weight ratio is 1: 5, be placed on the agitating ball 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, puts into then from climing combustion synthesis reactor, after vacuumizing, be filled with the high pure nitrogen of 7MPa, nickel filament with diameter 0.6mm is made heater, passes into 20 amperes electric current, duration 8s, make coil heating, temperature has reached the reaction temperature of silica flour and nitrogen in the raw mix, and chemical reaction mode with climing combustion in material successively advances then, and the reaction time continues after 18 minutes, reactor pressure begins to descend, reactor leads to circulating water, when the pressure of reactor drops to 6.5MPa, finishes from climing combustion reaction, pressure in the releasing reactor, do not have in the waste gas that discharges and contain F, the gas of Cl fills 3 minutes air to reactor, eliminates remaining a small amount of NH
3, open then the product that reactor takes out loose shape, remove the unreacted silica flour of surperficial one deck, the product integral body that obtains is milk yellow, and product weight has reached 2190 grams, and the silicon nitride purity that obtains after the fine grinding is greater than 98.8%, reaction yield＞95%.
The ESEM microscopic analysis shape appearance figure of synthetic product is seen Fig. 7 in this example, and X-ray diffraction analysis figure sees Fig. 8.Adopt the X-ray diffraction analysis standard measure to calculate its α and be mutually 97.8wt%, contents of free si is 0.10wt%.The oxygen level of powder is 1.35wt%, and nitrogen content is greater than 38.8%.
Claims (6)
1. self-combustion non-pollution prepares the method for alpha-phase silicon nitride powder fast, it is characterized in that it comprises the steps:
(1) raw material is handled: to granularity is that 100-300 purpose metallic silicon power carried out ball-milling processing 12-16 hour;
(2) batching: with the metallic silicon power after the above-mentioned processing is raw material, adds thinner, additive, and its weight percent is:
Metallic silicon power (handling the back): 30-45wt%,
Thinner 35-50wt%,
Additive 5-20wt%,
Above-mentioned diluent is stated and is the alpha silicon nitride powder, and additive is (NH
4)
2CO
3, (NH
4) HCO
3, CO (NH
2)
2In any one or any two kinds and two or more combinations;
(3) mix:, take out the back and sieves with the 40-60 eye mesh screen 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 on again in climing combustion reactor, after vacuumizing, use high pure nitrogen, pressure remains on 4-8MPa, and igniting guiding high temperature is synthetic from climing combustion, synthetic rear logical circulating water;
(5) get finished product: reaction post-reactor internal pressure can reduce, and when the pressure of reactor drops to 5-7MPa, finishes from climing combustion reaction, and the pressure in the releasing reactor fills 1-5 minute ordinary nitrogen or air to reactor, eliminates remaining small amount of N H
3, the block product that obtains loosening obtains the alpha-phase silicon nitride powder finished product after the fine grinding.
2. method according to claim 1, the purity that it is characterized in that described metallic silicon power is greater than 99.5%.
3. method according to claim 1 is characterized in that α phase content＞92% of described thinner α phase silicon nitride powder, and median size is 0.3-20 μ m.
4. method according to claim 1 is characterized in that described raw material treatment step adopts high energy ball mill or planetary ball mill to grind, and is placed in the cylinder of steel, with Si
3N
4A kind of or mixing in ball, the steel ball is as ball-milling medium.
5. method according to claim 1 is characterized in that described blend step adopts agitating ball mill or jar mill to carry out stirring ball-milling, is placed in the corundum tank, with Si
3N
4A kind of in ball, the steel ball or be mixed into ball-milling medium.
6. method 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, feed the direct current of 10-40A, time length 4～15s makes coil heating, and 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, finishes until reaction.
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| CN102583276A (en) * | 2011-12-30 | 2012-07-18 | 烟台同立高科工贸有限公司 | Method for producing regularly shaped alpha-phase silicon nitride powder |
| CN103159190A (en) * | 2013-03-11 | 2013-06-19 | 烟台同立高科新材料股份有限公司 | Preparation method of hyperpure nitride powder |
| CN104528672A (en) * | 2014-12-17 | 2015-04-22 | 青岛桥海陶瓷新材料科技有限公司 | Preparation method of alpha-silicon nitride |
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| CN102583276A (en) * | 2011-12-30 | 2012-07-18 | 烟台同立高科工贸有限公司 | Method for producing regularly shaped alpha-phase silicon nitride powder |
| CN103159190A (en) * | 2013-03-11 | 2013-06-19 | 烟台同立高科新材料股份有限公司 | Preparation method of hyperpure nitride powder |
| CN103159190B (en) * | 2013-03-11 | 2016-01-20 | 烟台同立高科新材料股份有限公司 | A kind of superpure nitrogen compound raw powder's production technology |
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| CN107673766A (en) * | 2016-08-02 | 2018-02-09 | 河北高富氮化硅材料有限公司 | A kind of structural ceramics high purity silicon nitride raw powder's production technology |
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| CN106380209B (en) * | 2016-11-16 | 2022-08-30 | 中国科学院理化技术研究所 | Large-scale combustion synthesis equipment with controllable temperature and pressure and application thereof |
| CN108996483A (en) * | 2018-10-26 | 2018-12-14 | 中国科学院理化技术研究所 | A kind of method of combustion synthesis of silicon nitride powder |
| CN110357050A (en) * | 2019-07-03 | 2019-10-22 | 南昌大学 | The shaft-like beta phase silicon nitride raw powder's production technology such as a kind of |
| WO2021008089A1 (en) * | 2019-07-16 | 2021-01-21 | 青岛瓷兴新材料有限公司 | Method for preparing silicon nitride powder by metal reduction |
| CN111074136A (en) * | 2019-12-16 | 2020-04-28 | 宁波博大申博企业管理有限公司 | Preparation method of high-toughness light wear-resistant steel |
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