Method for preparing high-toughness high-temperature-resistant directionally-arranged silicon nitride monolithic porous ceramic

Abstract

The invention relates to a method for preparing high-toughness and high-temperature-resistant silicon nitride monolithic porous ceramic, which comprises the following steps of: preparing beta-Si3N4 whiskers with high length-diameter ratio by using alpha-Si3N4 as a raw material and Y2O3 as an auxiliary agent through a normal-pressure sintering method, preparing tape casting slurry from the prepared beta-Si3N4 whiskers, directionally arranging the silicon nitride whiskers by using tape casting to prepare a thin film, and carrying out laminated sample preparation, thereby obtaining the high-toughness and high-temperature-resistant silicon nitride monolithic porous ceramic. SiO is subjected to high-temperature evaporation gas phase infiltration and reacts with residual carbon among fibers to obtain silicon nitride, and the silicon nitride monolithic porous ceramic material is prepared; the structure design thought of fiber directional arrangement and secondary silicon nitride bonding is provided, effective preparation of the porous ceramic constructed by the pure silicon nitride fibers is achieved, the advantage of anisotropy of the porous ceramic is exerted through directional arrangement, and therefore the fracture toughness of the silicon nitride ceramic is effectively improved, the high-temperature resistance is improved to the maximum extent through bonding of pure silicon nitride, and the service life of the porous ceramic is prolonged. The application range of the porous silicon nitride ceramic material is greatly expanded.

Description

technical field [0001] The invention belongs to the technical field of silicon nitride ceramic sintering, and in particular relates to a method for preparing high-toughness and high-temperature-resistant directional-arranged silicon nitride monolith porous ceramics, which is suitable for various high-temperature filter separators, catalyst carriers, sound-absorbing materials and transparent materials. wave materials, etc. Background technique [0002] As the speed of the missile increases, the working environment of the missile radome is getting worse, and the aerodynamic heating is very serious when the missile is flying in the atmosphere at hypersonic speed. In order to protect the normal operation of the aircraft communication, telemetry, guidance, detonation and other systems, the supersonic missile radome should have both high temperature resistance, ablation resistance, excellent mechanical properties and electrical properties. Silicon nitride material has many advant...

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Problems solved by technology

Patent No. 202110154424.3 discloses a method of preparing intergranular glass phase-free β-β-Si with high aspect ratio whiskers 3 N 4 The method of porous ceramics, the patent through molding process to prepare β-Si 3 N 4 The carbon source was introduced after compression molding, and the β-Si 3 N 4 Formation of α-Si at the overlap of whiskers 3 N 4 , to prepare Si 3 N 4 Lap β-Si 3 N 4 Whisker porous ceramic material, but its porosity is 51.2%, fracture toughness can only reach 3.1, so its performance is not ideal enough

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