Preparation method of high-density low-free-silicon-content reactively-sintered silicon carbide ceramic material

Abstract

The invention provides a preparation method of a high-density low-free-silicon-content reactively-sintered silicon carbide ceramic material. The method comprises the following steps: mixing, vacuum degassing, slip casting, demolding, drying and sintering. According to the invention, reasonable raw material particle size distribution is selected, and pressure slip casting is adopted to enhance thedensity of a biscuit of a product; an optimized sintering curve is adopted in the sintering process, and organic matter removal and presintering are combined into a whole, so sintering cost is reducedunder the condition that product quality is not affected, and the problem that the silicon carbide ceramic biscuit deforms or cracks in the high-temperature organic matter removal process is solved;and the high-density green body can undergo sufficient reactive sintering at a low temperature to generate a high-density low-free-silicon ceramic product, thereby ensuring the microstructure uniformity of the silicon carbide ceramic biscuit and greatly enhancing 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 method for preparing a high-density and low-content free silicon reaction sintered silicon carbide ceramic material. Background technique [0002] Silicon carbide ceramics 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., especially oxidation resistance is all non- The best one among cermets, in which silicon carbide prepared by reaction sintering has the advantages of low temperature and net size, which is a method widely used in industry, and is often used in electronic packaging, aerospace, military, automotive industries and other complex special-shaped production of parts. [0003] The existence of residual silicon in reaction sintered sili...

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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

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