Silicon nitride/silicon carbide complex phase porous ceramic and preparation method thereof

Abstract

The invention discloses a Si3N4 / SiC complex phase porous ceramic of which the nitriding ratio is higher than 85% and the porosity is 30-60%. The preparation method comprises the following steps: (1) by using Si and SiC as raw materials, adding a sintering assistant, and uniformly mixing by ball milling to obtain a slurry; (2) drying the slurry, screening, carrying out dry pressing, and carrying out cold isostatic pressing treatment to form a biscuit; and (3) putting the biscuit in a sintering furnace, heating to 900-1200 DEG C and then to 1300-1500 DEG C in a high-purity nitrogen atmosphere, sintering by nitriding reaction, cooling, and finally carrying out furnace cooling. The sintering method has the characteristics of short sintering time, simple technique, low energy consumption and the like, can easily obtain the Si3N4 / SiC complex phase porous ceramic material with net size molding, complicated shape, high porosity, controllable gap and oriented and interconnected gap structure, and is simple for molding; and the maximum bending strength can reach 150 MPa.

Description

technical field [0001] The invention belongs to the technical field of porous ceramics, in particular to a Si 3 N 4 Composite porous ceramic with SiC and its preparation method. Background technique [0002] Silicon nitride and silicon carbide (Si 3 N 4 With SiC, Si 3 N 4 / SiC) composite porous ceramics have shown broad applications in the fields of high-temperature gas filtration, sensors, catalyst supports, separation membranes, and thermal insulation materials due to their advantages of high strength, high toughness, wear resistance, corrosion resistance, and good chemical stability. Application prospect. [0003] He Xinbo et al. (Chinese patent ZL101913878) used SiC powder, Si 3 N 4 The powder and sintering aids are mixed with paraffin-based multi-component binder to form a uniform feed. After the preform obtained by injection molding is melted, thermally desorbed, and pre-sintered at 1150-1200 ° C, it is placed in a vacuum carbon tube. The furnace is sintered a...

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Problems solved by technology

[0005] The present invention aims at Si in the prior art 3 N 4 / SiC composite porous ceramics have technical problems such as uneven void structure, poor directional interconnectivity, poor net size forming, and low bending strength. The purpose is to provide a Si 3 N 4 Composite porous ceramics with SiC, the Si 3 N 4 The nitriding rate of SiC composite porous ceramics is higher than 85%, preferably higher than 87%, more preferably higher than 90%; the porosity is 30-60%, preferably 32-40%, more preferably 35- 38%

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