Preparation method of high-porosity silicon carbide-based porous ceramic material

Abstract

The invention discloses a preparation method of a high-porosity silicon carbide-based porous ceramic material, and the method is a technology for preparing a high-strength porosity-controlled siliconcarbide-based porous ceramic material by reacting phosphoric acid as an additive with a silicon carbide surface oxide layer. Specifically, the method comprises the steps of conducting surface oxidation treatment on a silicon carbide ceramic powder having a particle diameter of 0.5 to 20 [mu]m so as to generate a silicon oxide oxide layer on the surface of the silicon carbide raw material powder, and then directly uniformly mixing liquid phosphoric acid used as an additive with the treated raw material powder, wherein the amount of the phosphoric acid added is 5 to 35 wt%; conducting compression molding on the mixture, and then conducting cold isostatic pressing treatment to obtain a green body; then conducting normal-pressure sintering on the green body in an inert gas atmosphere of 900 to1500 DEG C, and controlling the reaction temperature increase rate to be 0.5-5 DEG C / min and the temperature-keeping time to be 2 to 5 hours. The invention has the advantages of simple process, low cost and high repeatability, and the prepared silicon carbide-based porous ceramic material has stable pore structure and does not easily produce defects.

Description

Technical field [0001] The invention relates to the field of ceramic materials, in particular to a low-temperature preparation technology of silicon carbide-based porous ceramic materials with high strength, high porosity and controllable porosity. technical background [0002] Silicon carbide-based porous ceramics is a new type of ceramic material developed based on silicon carbide ceramics and porous ceramics. In addition to the excellent properties of general porous ceramics such as high porosity, small bulk density and large specific surface area, it also has excellent mechanical properties , High temperature resistance, corrosion resistance, high thermal conductivity, low coefficient of thermal expansion and excellent thermal shock resistance, and other excellent physical properties of silicon carbide itself, can be widely used in chemical, environmental protection, biological and other fields as filtration, sound absorption, separation, catalyst carrier And bioceramics and ...

AI Technical Summary

Problems solved by technology

The particle accumulation sintering method is the simplest preparation method. The principle is to use the sintering properties of the ceramic particles themselves. During the sintering process, the particles form neck connections, so that the particles accumulate to form porous ceramics. Due to the pores of the particle accumulation sintering method It is basically transformed from the accumulation gap of the particles. Therefore, the porosity and pore size of the porous ceramic product can be controlled by changing the powder size, the type of binder, the amount of addition and the sintering parameters; the template method is used to prepare porous silicon carbide ceramics. , it is necessary to inject ceramic slurry or precursor into the template material with porous structure, and then obtain porous ceramics with a structure similar to the template material through a series of treatments. This method can prepare porous ceramics with a specific pore structure, but its preparation process is relatively Complicated and time-consuming; foam molding method is also one of the more common preparation methods, which is to add gas or substances that generate gas through subsequent processing into the ceramic body or precursor, and then sinter to obtain porous ceramics

The porosity, pore size and pore size distribution of porous silicon carbide ceramics prepared by foam molding are directly related to the temperature of the gas. Its biggest advantage is that the pore structure is not easy to produce defects, but it is difficult to obtain ceramics with a small range of pore size distribution; adding pore making The agent method is to add a pore-forming agent to the silicon carbide powder or precursor, remove the pore-forming agent through a subsequent process, form pores in the position occupied by the pore-forming agent, and then sinter to form a porous ceramic. This method can be convenient It is difficult to control the porosity, pore morphology, pore size and distribution of porous ceramics, but it is difficult to balance porosity and mechanical properties

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