Exploring the properties of porous silicon carbide ceramics

The special properties of porous silicon carbide ceramics are mainly due to its special porous structure, which contains porosity, pore size and distribution, and shape of holes. Therefore, it is necessary to regulate its porosity, pore size and distribution, and pore shape through the preparation method to obtain the desired porous structure. So its preparation method has been the focus of research.

Properties of porous SiC Ceramics

1. Pore properties

① Porosity

Porosity is the percentage of the volume occupied by pores in a porous Material to the total volume of the porous material (including open pores, half-open pores and closed pores of 3 kinds). Research shows that the performance of porous materials mainly depends on the porosity.

② Pore morphology

Pore morphology refers to the morphology of pores in porous ceramics. When the pores are equiaxed pores, the overall performance of the material is isotropic; but when the pores are striped or flat, such as through the carbonization of wood prepared by the silicon reaction sintering porous SiC ceramics, the pore structure is a certain direction.

③ Pore diameter and distribution

Pore diameter of less than 2nm for microporous materials, pore size between 2 ~ 50nm for mesoporous materials, size greater than 20nm for macroporous materials. By the pore size and distribution of the greater impact of performance, including permeability, permeability rate and filtration performance.

2. Mechanical properties

Porous SiC ceramic materials are brittle and their mechanical properties are usually characterized by bending or compression strength. Porosity and preparation method have a large impact on the mechanical properties of porous SiC ceramics.

3. Thermal Conductivity

Porosity and pore morphology have a large impact on the thermal conductivity of porous ceramics. For porous ceramics with uniform pore distribution, the thermal conductivity decreases gradually as the pore rate increases. However, due to the pore morphology of porous ceramic materials prepared by different processes, there are large differences, so the heat transfer process is correspondingly variable and complex.

Porous SiC ceramics have the excellent physical properties of SiC itself, such as high bulk density, high specific surface area, high hardness, corrosion resistance, high temperature resistance, high thermal conductivity, low coefficient of thermal expansion, and resistance to thermal shock, on top of the satisfaction of the porous nature of the ceramics.