Effect of non-static pre-oxidation treatment on the cyclic ablation behavior of SiC-ZrC/SiC multilayer coated graphite

Abstract

SiC-ZrC based ceramics have caught much attention as coatings for graphite materials. However, the coefficient of thermal expansion (CTE) mismatch between coatings and matrix severely limits their application in harsh environments. Herein, we proposed a non-static pre-oxidation treatment under an air pressure of 0.05 MPa to increase the surface roughness of graphite matrix to 18.054 μm and then prepared the SiC-ZrC/SiC multilayer coating on the pre-oxidized graphite. The results demonstrate that a firm interlocking structure was formed between SiC-ZrC/SiC multilayer coating and graphite matrix, which effectively improved the bonding strength and enhanced the cyclic ablation resistance of coatings. The bonding strength of SiC-ZrC/SiC multilayer coated on graphite pre-oxidized under negative pressure was 5.70 ± 0.42 MPa, which was 54.89 % higher than that on graphite pre-oxidized under atmospheric pressure (3.68 ± 0.08 MPa). After the plasma ablation for 360 s (60 s × 6), the linear and mass ablation rates of SiC-ZrC/SiC multilayer coated graphite which was pre-oxidized under negative pressure were −0.083 μm/s and 0.101 mg/s, respectively.