A method for preparing reaction-sintered silicon carbide ceramic material with high density and low content of free silicon

Abstract

The invention provides a method for preparing a reaction-sintered silicon carbide ceramic material with high density and low content of free silicon. The preparation method includes the steps of mixing materials, vacuum degassing, grouting molding, demolding and drying, and sintering, wherein a reasonable particle size of raw materials is selected. Grading, and the use of pressure grouting to enhance the density of the green body of the product; in the sintering process, the optimized sintering curve is adopted, the removal of organic matter and the pre-sintering are integrated, and the sintering cost is reduced without affecting the product quality. Reduce the deformation or cracking of the silicon carbide ceramic green body during the process of removing organic matter at high temperature; enable the high-density green body to fully react and sinter at a lower temperature to produce high-density, low-free silicon ceramic products, ensuring carbonization The microstructure of the silicon ceramic green body is uniform, which greatly improves the strength and structural stability of the ceramic material.

Description

technical field [0001] The invention belongs to the technical field of ceramic material preparation, and in particular relates to a preparation method of a high-density and low-free silicon content reaction sintered silicon carbide ceramic material. Background technique [0002] Silicon carbide ceramic is an industrial material with high mechanical strength, high hardness, high temperature resistance, chemical corrosion resistance, excellent oxidation resistance and thermal shock resistance, good thermal conductivity, low expansion coefficient, etc. The best one among cermets, in which silicon carbide prepared by reaction sintering has the advantages of low temperature and net size. production of parts. [0003] The existence of residual silicon in the reaction sintered silicon carbide is inevitable, which limits the use temperature and use environment of the reaction sintered silicon carbide. However, unilaterally reducing the content of silicon cannot improve the overall...

AI Technical Summary

Problems solved by technology

However, although the silicon carbide ceramics prepared by the dry pressing molding process have a high density, the structural uniformity is poor, and products with complex shapes cannot be made, mainly in the form of sheets and plates; although the products produced by extrusion molding have a higher density than grouting molding , but it is also impossible to make products with complex shapes, mainly rod-shaped beams; the injection molding process requires a large amount of organic binder, and the shrinkage of the ceramic green body is large, so it is impossible to prepare silicon carbide ceramic materials with a high volume fraction. Silicon carbide ceramic materials with high performance requirements cannot be achieved; although the existing slip casting method can produce special-shaped products with complex shapes, the product density is low, the highest can only reach 3.06-3.08g / cm3, which cannot meet high mechanical properties requirements and cannot be applied to areas with higher technical requirements

Images