Synthetic silicon oxynitride raw material and preparation method thereof

Abstract

The invention relates to a synthetic silicon oxynitride raw material and a preparation method thereof. A technical scheme adopted in the invention is characterized in that the method comprises the following steps: mixing 50-60wt% of elemental silicon with 40-50wt% of silica, and carrying out ball milling in a ball mill until the granularity is 4.5-6.5[mu]m to obtain a ball milled powder; and putting the ball milled powder in an atmosphere furnace, heating in highly pure nitrogen atmosphere at a heating rate of 10-12DEG C / min to 1000-1100DEG C, heating at a heating rate of 6-8DEG C / min to 1400-1500DEG C, and carrying out heat insulation for 4-9h to obtain the synthetic silicon oxynitride raw material. The method has the advantages simplicity, short production period, low cost, and no need of special synthesis devices or processing technologies; and the prepared synthetic silicon oxynitride raw material has the characteristic of high Si2N2O purity and completeness of grown crystal grains.

Description

technical field [0001] The invention belongs to the technical field of silicon oxynitride. Specifically relates to a raw material for synthesizing silicon oxynitride and a preparation method thereof. Background technique [0002] Silicon oxynitride (Si 2 N 2 O) is SiO 2 -Si 3 N 4 The only compound in the system, but Si 2 N 2 O has been considered to be in Si 3 N 4 A stable by-product formed during the synthesis and not studied in depth. Silicon oxynitride (Si 2 N 2 O) With excellent oxidation resistance, thermal shock resistance, corrosion resistance, creep resistance, high temperature strength, high density, low expansion rate and other excellent properties, it is an excellent high temperature structural material and refractory material. Studies have shown that silicon oxynitride has a transitional structure between silicon oxide and silicon nitride, and its high strength is determined by the self-strengthening and toughening mechanism caused by the diversity of...

AI Technical Summary

Problems solved by technology

[0003] At present, the research on silicon oxynitride at home and abroad is still very limited. The main reason is that silicon oxynitride has always been regarded as an undesirable product in the process of synthesizing silicon nitride, so it has not been paid attention to; One reason is that it is difficult to obtain silicon oxynitride powder with high purity, and it is difficult to sinter silicon oxynitride powder, and it is difficult to obtain dense silicon oxynitride products. 2 N 2 O decomposes above 1600°C

[0004] Currently Si 2 N 2 The specific methods of O synthesis are: (1) SiO 2 with Si 3 N 4 High temperature (>1700°C) solid phase reaction synthesis, the disadvantage is that the synthesis temperature is high, and the synthesized Si 2 N 2 O will decompose at high temperature, and the gaseous SiO will be lost, resulting in the loss of reaction raw materials; and during the reaction, Si 3 N 4 , SiO 2 Insufficient contact, the solid phase reaction cannot be completely carried out, and uniform Si cannot be generated 2 N 2 O phase

(2) Carbothermal reduction of SiO in nitrogen 2 , forming a Si-N-C-O complex system, there are many side reactions, many by-products are formed, and the reaction process is difficult to control

(3) SHS reaction synthesis of silicon-containing organic compounds, the disadvantage is that the reaction cycle is relatively long, up to 20~50h, and the atmosphere is not easy to control

(4) Si and SiO 2 The mixture is reacted and synthesized under high temperature nitrogen atmosphere, and there is Si at high temperature 3 N 4 A large amount of generation affects the final synthesis product, and at high temperature, elemental silicon is easy to soften and close the pores, which makes the diffusion of nitrogen difficult and prolongs the reaction time. The synthesis reaction process is sensitive to temperature and oxygen partial pressure.