The Fabrication Technology Of The Hemp Straw Sic Ceramics By Dry Pressing Process

The hemp straw, with natural nanoscale porous structure, is low-cost, and super activated carbon materials can be obtained after carbonization and activation process; Dry pressing with high molding efficiency and dimensional stability of the product prepared by this method, it is suitable for industrial production.In this paper, the hemp straw was used as raw material, and it was formed into pure carbonaceous preforms by dry pressing. These preforms were characterized according to their vertical density profile, microstructures and pore structures. in the density of pure carbon porcelain body, microscopic structure and the characteristic are analyzed. The hemp straw silicon carbide ceramic was prepared by reaction sintering the pure carbonaceous preforms, and the vickers hardness, flexural strength, elastic modulus and fracture toughness mechanical properties of the ceramics were tested. The experimental results show that:(1) In the dry forming process, when carbon powder moisture content was8%～12%, high strength performs could be prepared, less prone to emerge delamination, cracking and other defects. Preforms density increased with the molding pressure, it was no longer increased until it reached about0.94g/cm3.(2) The preporms obtained with uniform microstructure and the pore size of the performs were between1～80μm, when the carbon powder moisture content was8%～10%and forming pressure was20MPa～35MPa.(3) The sintering temperature is1550℃, the degree of vacuum is10Pa～30Pa, the silicon content is1.2times the theoretical value, holding30min, which were the optimum process parameters for the biomorphic SiC ceramics production.(4) With the increased density of the hemp straw silicon carbide ceramic, the corresponding mechanical properties had tended to increase. Mechanical properties:Vickers hardness, flexural strength, elastic modulus and fracture toughness reached a relatively high level when the density was2.913g/cm3. Compared to the internationally renowned ceramic manufacturer(M Clubed Inc.et al.), the mechanical properties of the hemp straw SiC Ceramics reached a similar level.