Mechanical properties of C/SiC/Si-Mo-Cr multilayer coated carbon/carbon composites

A novel C/SiC/Si-Mo-Cr multilayer oxidation protective coating for carbon/carbon composites was prepared by pack cementation and slurry method. The microstructures of the as-prepared multilayer coating were characterized by XRD and SEM analyses. The effects of the coating processing and thermal shock on the mechanical properties of carbon/carbon composites were investigated by three point bending tests. The results show that the asobtained multiphase coating is dense, and the flexural strength of carbon/carbon composites after coating increases and the fracture behavior changes from the pseudoplastic fracture to brittle fracture mode. After enduring the thermal cycling between 1500°C and room temperature for 20 cycles, the flexural strength of the coated specimens decreases accordingly, and the plastic increases.