Porous SiC Ceramics with Controllable Porosity Achieved by Micro-sized Powder through Recrystallization Sintering

Abstract

Abstract Porous silicon carbide (SiC) ceramics with various porosity and pore size were successfully fabricated by adjusting the particle size and content of fine powder via recrystallization sintering process. The effects of the addition of fine powder with different particle size on the micromorphology of porous SiC ceramic and the flexural strength were investigated. With the increase of the fine powder content from 5wt% to 20 wt%, the porosity and pore size decrease, and the crystal grains gradually become larger and tend to round. The neck area among grains increases, leading to the improvement of flexural strength. The mechanism for promoting the sintering of porous SiC ceramics lies in the evaporation-condensation process of fine powder at high temperature. The finer particles are easier to be evaporated to promote the growth of coarse grain and the development of grain neck, so that the porosity and pore size were smaller, and the flexural strength was enhanced. At the addition of F4 powder of 20 wt%, the porous SiC ceramics with the porosity and MFP size of 39.1% and 1.38 μm respectively, and the flexural strength of 54.49MPa were obtained.