Factors affecting the density of C/C-SiC composite

Abstract

C/C-SiC composites were prepared by precursor transformation method. The microstructure and properties of the samples were analyzed. The effects of silicon infiltration temperature, holding time, vacuum degree and cracking cycle on the density of C/C-SiC composite were studied. The results show that with the increase of siliconizing temperature, the density of the material increases at first, and then decreases rapidly. With the increase of heat preservation time, the density of the material increases rapidly at first, keeps stable for a period of time and then decreases slowly. With the increase of sintering vacuum, degree, the density of the material increases rapidly. With the increase of cracking cycle, the density of the material increases continuously, but the growth rate decreases gradually. After 11 cycles of “impregnation curing cracking” process, the C/C-SiC composite prepared obtained a maximum density of 2.09 g/cm3 and a minimum porosity of 7.6%. At this time, it also has the most excellent comprehensive mechanical properties: bending strength of 468 MPa, tensile strength of 242 MPa, fracture toughness of 19.6 MPa·m1/2 and Vickers hardness of 17.2 GPa.

Keywords

• c/c-sic composite
• density
• porosity
• mechanical properties