Normal pressure thermal explosion method for preparation of high purity silicon oxynitride ceramic powder

Abstract

The present invention belongs to the technical field of preparation of high purity silicon oxynitride ceramic powder, and relates to a normal pressure thermal explosion method for synthesis of a silicon oxynitride ceramic powder. The method is characterized by including the stages of raw ingredient preparation, mixing, thermal explosion synthesis, and acquisition of a finished product. The steps are as below: fully mixing a Si powder and a SiO2 powder by weight ratio of 40-45:55-60; conducting thermal explosion synthesis at 1380-500 DEG C for 3-15 minutes; conducting gravity separation on the thermal explosion products in a solution medium for 2-5 min; and filtering and drying the suspension to obtain a silicon oxynitride finished product. The obtained product has high purity, no impurity phase and high powder sintering activity. The invention is characterized in that the production process does not need any diluent or catalyst, and is simple, low in cost, and easy to realize large-scale continuous production.

Description

technical field [0001] The invention relates to a preparation method of silicon oxynitride powder. The invention belongs to the field of inorganic non-metallic materials, and the prepared silicon oxynitride powder can be widely used in the fields of special ceramics, high-end refractory materials, and quartz crucible coatings for solar polysilicon ingots. Background technique [0002] Silicon oxynitride has similar physical and chemical properties to silicon nitride, and its thermal shock resistance, oxidation resistance and chemical stability are better than silicon nitride. It is an excellent high-temperature structural material and refractory material. At the same time, the silicon oxynitride material also has the characteristics of high body resistance, preventing metal diffusion, excellent dielectric properties and optical properties, and can be used as an anti-reflection film for semiconductor thin films, Rugate filters, etc. In addition, the anti-neutron radiation pe...

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Problems solved by technology

Synthetic method (1) high reaction temperature (>1700 o C), high energy consumption, and unavoidable residual SiO that did not participate in the reaction 2 and Si 3 N 4 In addition, the price of silicon nitride raw materials is relatively expensive, which limits its wide application; the synthesis method (2) has a relatively simple process, and the source of raw materials is also economical and convenient

However, many side reactions may occur in the reaction system, and it is difficult to obtain pure silicon oxynitride products, and there is some carbon pollution in the products; the synthesis method (3) is limited to the synthesis of amorphous silicon oxynitride powders, and The reaction time is up to 40 hours; the synthesis method (4) direct nitriding reaction of silicon powder requires strict control of O 2 The partial pressure and the competitive reaction of nitrogen and oxygen make the yield of nitrogen oxide products lower; the synthesis method (5) requires high temperature and long-term process conditions under normal pressure conditions, and the synthetic products often contain a certain amount of by-product nitrogen. Silicon oxide and / or residual raw materials, it is difficult to obtain pure phase silicon oxynitride powder; under high pressure (4~14 MPa) conditions, the synthesis of silicon oxynitride powder can be realized by self-propagating high-temperature synthesis process, but nitrogen needs to be added Silicon nitride or silicon oxynitride diluent is used to control the reaction process. Also, due to many side reactions, it is easy to generate β-phase silicon nitride, cristobalite and other by-product phases.

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