Method for preparing porous silicon carbide ceramic

The invention discloses a method for preparing porous silicon carbide ceramic, and relates to a method for preparing silicon carbide ceramic. The invention aims to solve the technical problems of low mechanical properties and low porosity of porous silicon carbide ceramic prepared through the existing method. The method comprises the following steps of 1, preparing pulp; 2, preparing a porous ceramic green body; 3, preparing a prefabricated body; 4, preparing carbon gel; 5, preparing a composite material of silicon carbide and the carbon gel; 6, preparing a composite material of porous silicon carbide and carbon aerogel; and 7, putting the composite material of the porous silicon carbide and the carbon aerogel and monatomic silicon powder into a sintering furnace to be sintered to obtain the porous silicon carbide ceramic. The porosity of the opening of the porous silicon carbide is 30-83 percent, the aperture size is 0.3-100m, and pore spaces can be uniformly distributed or directionally arranged. Through a three-point bending test, the bending strength of the finally prepared porous silicon carbide ceramic material with the porosity of 47.8 percent achieves 164.62 MPa.