Production method of high-content silicon nitride (Si3N4) powder

Abstract

The invention discloses a production method of silicon nitride (Si3N4) powder, in particular relates to a new production method of Si3N4 with relatively high content, and belongs to the technical field of inorganic chemistry. The method comprises the following steps of: firstly, carrying out pre-treatment on raw material powder in a mechanical activation mode, and adding a proper amount of alpha-Si3N4 as a diluent during the direct nitridation of silicon powder at a high temperature and under normal pressure; and finally, synthesizing the high-content Si3N4 powder by controlling the addition proportion of the diluent, nitridation time and temperature. By the production method, the activity of a solid-phase reactant is improved, and the reaction of Si and N2 is strengthened. The process has the advantages that: high-temperature and high-pressure environments are not required; operation is simple; the raw material is easy to obtain; the process is high in product purity, low in cost, high in efficiency, environment-friendly, safe and energy-saving; and the process is economical, efficient and applicable to large-scale production.

Description

technical field [0001] The present invention relates to a kind of production method of silicon nitride powder, especially relate to a kind of silicon powder production content higher Si 3 N 4 The new method belongs to the technical field of inorganic chemistry. Background technique [0002] Silicon nitride (Si 3 N 4 ) is an important structural material, known as the "all-around champion" in ceramic materials. It is a superhard substance, which is not only an excellent high-temperature structural material, but also a new type of functional material. It has lubricity and wear resistance. It does not react with other inorganic acids except hydrofluoric acid. It has strong corrosion resistance and oxidation resistance at high temperatures. It can also resist cold and heat shocks and can be heated to 1000°C in the air. Above, rapid cooling and rapid heating will not shatter. In terms of physical properties, silicon nitride materials have high hardness, wear resistance, lar...

AI Technical Summary

Problems solved by technology

The quality of silicon nitride powder depends on its preparation method. At present, the commonly used preparation methods are: direct silicon powder nitriding method, carbothermal reduction method, silicon halide ammonium solution method, preparation of precursor method, chemical double decomposition method, in-situ synthesis method , silicon alloy ammonolysis method, etc., generally have the following disadvantages: it is prepared by sintering of large-particle silicon nitride and multi-phase powder, with high brittleness, poor uniformity, low reliability, poor toughness and strength, which greatly restricts its application.

The high-pressure synthesis process not only increases the production cost due to high equipment investment, but also brings safety hazards to production

Judging from the index test and test firing results of silicon nitride powder at home and abroad, the Si produced by the most representative domestic enterprises 3 N 4 The average particle is about 3 microns, and the content of metal impurities is high, which makes it difficult to meet the requirements of qualified products, while the imported powder is less than 0.7 microns

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