Preparation method of alumyte base beta-sialon

Abstract

The present invention provides a method for preparing beta-Sialon powder. The method uses bauxite as raw material, adds metal silicon pwoder, aluminium powder and crystal seed, and adopts nitriding reduction process to prepare bauxite base beta-Sialon. The method is simple, its condition is easily controlled, and the obtained product is higher in purity, the beta-Sialon content is above 80%. Said powder material can be extensively used in the fields of metallurgical industry, mechanical industry and ceramic industry, etc.

Description

[0001] Field: [0002] The invention relates to a method for preparing ceramic powder, in particular to a method for preparing β-Sialon by reduction and nitrogenation of high alumina bauxite. Background technique: [0003] Sialon (Sialon) is Si 3 N 4 with Al 2 o 3 The solid solution was first proposed by K.H.Jack et al. in 1972. Si 3 N 4 With β-Si 3 N 4 and α-Si 3 N 4 The two variants and their solid solutions with the same structure are called β-Sialon and α-Sialon respectively. Sialon material has good comprehensive properties and has received extensive attention in recent years. Such as: the same single-phase oxide material (Al 2 o 3 etc.), they have much superior thermal shock resistance, and high-temperature mechanical properties are equivalent, and have good corrosion resistance to a variety of smelting slags; compared with single-phase non-oxides (such as Si 3 N 4 , SiC, etc.), they have a much higher oxidation resistance. These characteristics make Sial...

AI Technical Summary

Problems solved by technology

For decades, there have been a lot of researches on all aspects of Sialon materials, but its practical application is still limited. This is because: (1) The synthesis of Sialon by the direct reaction method requires the synthesis of Si 3 N 4 and AlN powder, followed by SiO 2 、Si 3 N 4 、Al 2 o 3 , AlN as the raw material, according to the Si-Al-O-N phase diagram mixed in a certain proportion, then synthesized by solid-state reaction at high temperature, the process of this method is relatively complicated, and the synthesized Sialon powder is often accompanied by the existence of many impurity phases, And generally require a higher sintering temperature (about 1700 ° C), and the method is expensive, such as the Si 3 N 4 The price exceeds 1000RMB / Kg, and the price of domestic AlN powder also exceeds 600RMB / Kg; (2) Metal Si, Al and their oxides are used as starting materials to react and sinter into Sialon powder, and the process cost is also relatively high

(3) Sialon powder is synthesized by carbothermal reduction and nitriding using clay as raw material. This process has problems such as many impurities in the synthetic product, large amount of impurities, and difficulty in control.

But because the raw material quality is not stable enough, the composition is not uniform enough, and the variety is single, not only can't meet the demand of special refractory materials, the sales price in the international market is also far lower than Guyana, Brazil and other countries (such as the price of bauxite clinker in my country is about 70- 80 US dollars / ton, while the price of Guyana and Brazil is about 155-165 US dollars / ton)

Images