Carbon/Silicon Carbide Composites with Interphases Processed by Temperature-pulsing Chemical Vapor Infiltration Technique

A novel method of temperature-pulsing chemical vapor infiltration (T-pulsing CVI) was introduced. And interfacial coatings of silicon carbide (SiC) layer and pyrolytic carbon (PyC) layer were processed via the route. 3D carbon fiber preforms were densified by forced-flow thermal-gradient chemical vapor infiltration (FCVI) with the precursor of hexamethyldisilazane (HMDS). The microstructure of interphases was investigated by transmission electron microscope (TEM). The configuration of specimens' fracture surface was observed by scanning electron microscope (SEM). Results show that the density of the composites is 1.98g·cm-3. The thickness of the SiC layer estimated is 20nm, and 50nm for the PyC layer. The average flexural strength of the composites is 458MPa at room temperature, and the average fracture toughness is 19.8MPa·m1/2.