CN1251996C - Preparation for combustion synthesis of beta-silicon nitride stick grain with magnesium silicon nitride as growth aid - Google Patents

Preparation for combustion synthesis of beta-silicon nitride stick grain with magnesium silicon nitride as growth aid Download PDF

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CN1251996C
CN1251996C CN 200410017913 CN200410017913A CN1251996C CN 1251996 C CN1251996 C CN 1251996C CN 200410017913 CN200410017913 CN 200410017913 CN 200410017913 A CN200410017913 A CN 200410017913A CN 1251996 C CN1251996 C CN 1251996C
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powder
rod
brilliant
beta
combustion synthesis
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CN 200410017913
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CN1569742A (en
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彭桂花
江国健
李文兰
张宝林
庄汉锐
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Shanghai Institute of Ceramics of CAS
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Shanghai Institute of Ceramics of CAS
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Abstract

The present invention relates to a combustion synthesis preparation method for beta-Si3N4 bar crystals by using magnesium silicon nitride as growth assistant, which belongs to the preparation field of non-oxide ceramic bar crystals. The present invention is characterized in that commercial silicon powder and alpha-Si3N4 powder are mixed in the proportion of 9 to 5: 1 to 5, and the MgSiN2 is additionally added as the growth assistant; the reaction preparation is carried out in nitrogen gas of 1 to 10MPa. The bar crystal growth assistant adopts the novel magnesium silicon nitride of which the addition amount is 0.5 to 15 wt% of the total mixed weight of the silicon powder and the alpha-Si3N4 powder. During the preparation process, blocks do not need pressing in advance, and the reaction is carried out in an upright annular barrel made of carbon felt or in a disc-shaped container. The combustion synthesis technology adopted by the present invention has the advantage of low energy consumption, and is suitable for industrial largescale production; in addition, combustion products also has the characteristics of high purity, no need of post-treatment, no environmental pollution, etc.; furthermore, the length-diameter ratio of the prepared beta-Si3N4 bar crystal is between 5 and 15; the crystal structure is integrated, and the surface is smooth.

Description

It is brilliant to be equipped with the beta-silicon nitride rod with silicon nitride magnesium as growth auxiliary agent burning synthesis for preparing
Technical field
The present invention relates to beta-silicon nitride (β-Si 3N 4) the brilliant preparation method of rod, more precisely with silicon nitride magnesium (MgSiN 2) powder is as growth auxiliary agent burning synthetic (CS) preparation β-Si 3N 4The method that rod is brilliant belongs to the brilliant preparation field of non-oxide ceramics rod.
Background technology
Advanced structural ceramic has a series of unique excellent physics, chemistry and biological properties under normal temperature and high temperature, such as intensity and hardness height, creep is little, anti-oxidant, wear-resistant, corrosion-resistant and have better compatibility etc. with organism, therefore the many departments in high-technology field and modern industry production have broad application prospects.But the fragility of stupalith is its deadly defect, has restricted it and has used more widely.The engineering structure stupalith is that its toughness increases substantially from the distinctive marks that development enters practicability.Decades, the achievement in research of stupalith showed, improve differing materials systems engineering ceramics toughness mainly by two kinds of approach: 1. preparation technology parameter reasonable in design, defects count and size in the final microstructure of control goods, impel material inside organization structure to form certain configuration, make crystal grain develop into class whisker long grain shape, with induced in-situ from toughening mechanisms; Or by stress induced transformation toughening mechanisms.2. add that whisker, fiber, rod are brilliant, the second phase material of high elastic coefficient such as particle and upper layer, high strength, high tenacity to ceramic substrate mutually in to increase toughness.
β-Si 3N 4Have high strength, high-modulus, high dielectric property, high temperature resistant, low-expansion coefficient, good series of advantages such as chemical stability, its whisker or excellent crystal structure On Crack Propagation play bridging, bifurcated, deflecting action, thereby can significantly improve the fracture toughness of material, be considered to the desirable reinforcing component of light metal and ceramic material.
At present, preparation β-Si 3N 4Whisker mainly adopts method and the combustion synthesis method of long-time insulation under the high temperature.The former such as [J.Ceram.Soc.Japan, 1993,101, the 1078-1080] such as Kiyoshi HIRAO of Japan with α-Si 3N 4Be raw material, oxide Y 2O 3And SiO 2As the whisker growth auxiliary agent, insulation obtained β-Si in two hours under 1850 ℃, 0.5MPa nitrogen atmosphere 3N 4Whisker.Chen Dianying etc. [Mater.Res.Bull., 2002,37,1481-1485] adopt silica flour and α-Si 3N 4Be raw material, oxide Y 2O 3As the whisker growth auxiliary agent, burning synthesis for preparing is for β-Si under the nitrogen pressure of 3～10MPa Deng rare earth oxide 3N 4Whisker.
Although above two kinds of technologies can both prepare β-Si 3N 4Whisker, but remain in some shortcomings.Under the high temperature the long-time thermal-insulating method production cycle long, the while energy consumption is very big.Long-time thermal-insulating method has the advantages such as technology is simple, energy consumption is low, productive rate is high, small investment under the combustion synthesis method higher temperatures, but adopts oxide as the whisker growth auxiliary agent, has unavoidably introduced oxygen in product, causes occurring in the material lattice defect, so that β-Si 3N 4The performance of whisker is subjected to impact to a certain degree.In addition, the interpolation of oxide has produced liquid phase, with the SiO of silicon nitride surface 2Produce glassy phase, need post processing to be removed with acid, cause complex process.
The imagination that the inventor proposes as the growth auxiliary agent, prepares β-Si by combustion synthesis method with novel nitride silicon nitride magnesium powder 3N 4Rod is brilliant, it not only utilized combustion synthesis method easy, quick, energy-conservation, efficient, adapt to industrialized advantage, and prepare β-Si with non-oxidized substance as the auxiliary agent of growing 3N 4The rod crystalline substance can reduce the oxygen content of end product and simplify technology.According to known to the inventor up to the present, not yet see with the silicon nitride magnesium powder as the standby β-Si of growth auxiliary agent burning synthesis for preparing 3N 4The report that rod is brilliant.
Summary of the invention
The object of the present invention is to provide a kind of with silicon nitride magnesium as the standby β-Si of growth auxiliary agent burning synthesis for preparing 3N 4Rod is brilliant, to be applicable to the β-Si of scale synthesized high-performance 3N 4Rod is brilliant.
Combustion synthesis of beta-Si provided by the invention specifically 3N 4The rod crystal method is characterized in that:
(1) with silica flour and α-Si 3N 4Powder is the reaction initiation material, and both mixed proportions are 5～9: 5～1, employed α-Si 3N 4The α phase content of powder is＞83wt% that particle diameter is 0.3～30 μ m; Silica flour purity＞98wt%, particle size range is 0.5～50 μ m.
(2) with MgSiN 2Powder is as excellent crystals growth auxiliary agent, and its addition is silica flour and α-Si 3N 40.5～15wt% of gross weight after powder mixes.MgSiN 2Powder purity＞98wt%, particle diameter are 0.3～30 μ m.
Do not need briquetting to be directly mounted loosely in the ring-type or disc shaped container of carbon felt after the powder that (3) will contain excellent crystals growth auxiliary agent mixes, apparent density is 0.6～1.4g/cm 3, place then the burning synthetic furnace, pass into the nitrogen of 1～10MPa, through energising ignition trigger combustion synthesis reaction, generated time is 2～10 minutes, generally is no more than 8 minutes, synthetic β-Si 3N 4Rod is brilliant to be cooled off with stove.
Obviously, combustion synthesis of beta-Si provided by the invention 3N 4Rod crystalline substance and existing β-Si 3N 4The preparation method of whisker compares, and has following advantage:
(1) β-Si 3N 4The brilliant product purity height of rod, crystal structure is complete, does not contain glassy phase, need not carry out post processing, environmentally safe.
(2) adopt ring-type or disc shaped container, be suitable for large-scale production than crucible, the β-Si of preparation 3N 4The brilliant output of rod is big.
(3) β-Si 3N 4The brilliant smooth surface zero defect of rod, productive rate is near 100%.
(4) β-Si of preparation 3N 4The brilliant length of rod is longer, reaches more than 7～30 μ m, and diameter, 0.5～3 μ m, draw ratio 5～15 is suitable as materials reinforcing and uses.
Description of drawings
Fig. 1 is the upright ring-type tube of the carbon felt of employing in embodiment 1 provided by the invention and 2.
Fig. 2 is the disc shaped container of the carbon felt of employing among the embodiment 3 provided by the invention.
Fig. 3 (a), (b), (c) and (d) be embodiment 1 provided by the invention, 2,3,4 synthetic β-Si 3N 4The SEM shape appearance figure that rod is brilliant.
Fig. 4 (a), (b), (c) and (d) be embodiment 1 provided by the invention, 2,3,4 synthetic β-Si 3N 4The XRD collection of illustrative plates that rod is brilliant.Ordinate zou is an intensity, and X-coordinate is diffraction angle 2 θ.
Fig. 5 is a process flow sheet of the present invention.
1 is the tungsten filament heating element among the figure, and 2 is priming mixture, and 3 is that reactant 4 is carbon felt container.
Embodiment
Further illustrate characteristics of the present invention below by embodiment, but be not limited to embodiment.
Embodiment 1:
By technological process shown in Figure 5, earlier with silica flour and α-Si 3N 4Powder mixes in 1: 1 ratio, adds then excellent crystals growth auxiliary agent MgSiN 2Powder, addition are Si powder and α-Si 3N 4The 2.5wt% of powder gross weight, pine was loaded in the upright ring-type tube container of carbon felt of external diameter φ 60mm * internal diameter φ 55mm * high 60mm (Fig. 1) after powder evenly mixed, and apparent density is 0.65g/cm 3, and place the burning synthetic furnace, be filled with 5MPa nitrogen (purity 99.9%) after vacuumizing, through the synthetic β-Si of energising ignition 3N 4Rod is brilliant, and the reaction time is no more than 5 minutes, the synthetic rear nature cooling of adopting.
β-Si by above-mentioned technology preparation 3N 4The brilliant productive rate of rod is near 100%, and length is 5～20 μ m, and diameter is between 0.5～2 μ m, and average aspect ratio is approximately 10, and its crystal structure is complete, the smooth surface zero defect, and the product pattern is shown in Fig. 3 (a).Combustion product is Si through XRD determining 3N 4, its XRD analysis result is shown in Fig. 4 (a).
Embodiment 2:
By technological process shown in Figure 5, earlier with silica flour and α-Si 3N 4Powder mixes in 1: 1 ratio, adds then excellent crystals growth auxiliary agent MgSiN 2Powder, addition are Si powder and α-Si 3N 4The 7.5wt% of powder gross weight, pine was loaded in the disc shaped container of carbon felt (Fig. 2) after powder evenly mixed, and apparent density is 0.73g/cm 3, and place the burning synthetic furnace, be filled with 5MPa nitrogen (purity 99.9%) after vacuumizing, through the synthetic β-Si of energising ignition 3N 4Rod is brilliant, and the reaction time is no more than 5 minutes, the synthetic rear nature cooling of adopting.
β-Si by above-mentioned technology preparation 3N 4The brilliant productive rate of rod is near 100%, and length is 10～20 μ m, and diameter is between 1～2 μ m, and average aspect ratio is approximately 10.Its crystalline structure is complete, the smooth surface zero defect.The product pattern is shown in Fig. 3 (b).Combustion product is Si through XRD determining 3N 4, analysis result is shown in Fig. 4 (b).
Embodiment 3:
By technological process shown in Figure 5, earlier by technological process shown in Figure 5, earlier with silica flour and α-Si 3N 4Powder mixes in 1: 1 ratio, adds then excellent crystals growth auxiliary agent MgSiN 2Powder, addition are Si powder and α-Si 3N 4The 12wt% of powder gross weight, pine was loaded in the disc shaped container of carbon felt (Fig. 2) after powder evenly mixed, and apparent density is 0.74g/cm 3, and place the burning synthetic furnace, be filled with 5MPa nitrogen (purity 99.9%) after vacuumizing, through the synthetic β-Si of energising ignition 3N 4Rod is brilliant, and the reaction time is no more than 5 minutes, the synthetic rear nature cooling of adopting.
β-Si by above-mentioned technology preparation 3N 4The brilliant productive rate of rod is near 100%, and length is 5～15 μ m, and diameter is between 0.3～2 μ m, and average aspect ratio is approximately 12.Its crystalline structure is complete, the smooth surface zero defect.The product pattern is shown in Fig. 3 (c).Combustion product is Si through XRD determining 3N 4, analysis result is shown in Fig. 4 (c).
Embodiment 4:
By technological process shown in Figure 5, earlier with silica flour and α-Si 3N 4Powder mixes in 8: 2 ratio, adds then excellent crystals growth auxiliary agent MgSiN 2Powder, addition are Si powder and α-Si 3N 4The 2.5wt% of powder gross weight, pine was loaded in the upright ring-type tube container of carbon felt of external diameter φ 60mm * internal diameter φ 55mm * high 60mm (Fig. 1) after powder evenly mixed, and apparent density is 0.70g/cm 3, and place right burning synthetic furnace, be filled with 10MPa nitrogen (purity 99.9%) after vacuumizing, through the synthetic β-Si of energising ignition 3N 4Rod is brilliant, and the reaction time is no more than 8 minutes, the synthetic rear nature cooling of adopting.
β-Si by above-mentioned technology preparation 3N 4The brilliant productive rate of rod is near 100%, and length is 10～20 μ m, and diameter is between 1～2.5 μ m, and average aspect ratio is approximately 9.Its crystalline structure is complete, the smooth surface zero defect, and the product microstructure is shown in Fig. 3 (d).XRD analysis result (Fig. 4 (d)) mensuration combustion product is Si 3N 4
Can find out that from above-mentioned four embodiment the present invention adopts MgSiN 2Powder is as β-Si 3N 4The growth auxiliary agent of the brilliant preparation of rod, and by burning synthesis method, obtained β-Si that crystal structure is complete, product purity is high 3N 4Rod is brilliant.

Claims (5)

1. combustion synthesis of beta-Si 3N 4The method that rod is brilliant comprises batching, mixing, burns and synthesize, and it is characterized in that:
(1) with α-Si 3N 4Be the reaction initiation material with silica flour, both part by weight are 1～5: 9～5;
(2) with MgSiN 2Powder is as excellent crystals growth auxiliary agent, and addition is silica flour and α-Si 3N 40.5～15wt% of gross weight;
(3) above-mentioned steps (1) and (2) are contained the powder of excellent crystals growth auxiliary agent after even the mixing, pine is loaded in the container of carbon felt, place then the burning synthetic furnace, pass into the nitrogen of 1～10MPa, synthetic through ignition, reaction time is 2～10 minutes, naturally cooling in the synthetic rear stove; Apparent density is 0.6～1.4g/cm 3
2. by the described combustion synthesis of beta-Si of claim 1 3N 4The method that rod is brilliant is characterized in that described silica flour purity＞98wt%, and particle diameter is 0.5～50 μ m, α-Si 3N 4α phase content＞the 83wt% of powder, particle diameter are between 0.3～30 μ m, MgSiN 2Powder purity＞98wt%, particle diameter are 0.3～30 μ m.
3. by the described combustion synthesis of beta-Si of claim 1 3N 4The method that rod is brilliant, it is characterized in that containing excellent crystals growth auxiliary agent to mix the container that the powder pine is loaded on the carbon felt be in upright ring-type tube or the disc shaped container.
4. by the described combustion synthesis of beta-Si of claim 1 3N 4The method that rod is brilliant is characterized in that described generated time is no more than 8 minutes.
5. by the described combustion synthesis of beta-Si of claim 1 3N 4The method that rod is brilliant is characterized in that the β-Si for preparing 3N 4The brilliant length of rod is 7～30 μ m, and diameter is 0.5～3 μ m, and draw ratio is 5～15.
CN 200410017913 2004-04-23 2004-04-23 Preparation for combustion synthesis of beta-silicon nitride stick grain with magnesium silicon nitride as growth aid Expired - Fee Related CN1251996C (en)

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JP5281408B2 (en) * 2005-12-02 2013-09-04 クリスタル・イズ，インコーポレイテッド Doped aluminum nitride crystal and method for producing the same
CN103668012B (en) * 2012-09-26 2015-11-04 中国科学院上海硅酸盐研究所 A kind of enhancement type Cu-base composites and its preparation method and application
CN112898040B (en) * 2021-02-04 2022-05-06 西安交通大学 Method for preparing intercrystalline-free glass phase beta-Si by using high length-diameter ratio whisker3N4Method for producing porous ceramics

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