Zou Jizhao

TaSi2 Oxidation Protective Coating for SiC Coated Carbon/Carbon Composites

Abstract In order to improve the oxidation protective property of carbon/carbon composites at high temperature, TaSi 2 coating was prepared on the surface of SiC coated carbon/carbon composites by pack cementation technique. The crystal structure and morphology of the as-obtained coating was analyzed by XRD and SEM with EDS. The isothermal oxidation test was carried out in air at 1773 K. The results show that the as-prepared coating is composed of SiC, Si and TaSi 2 . The multilayer coating is about 200 μm in thickness, and there are no cracks in it. The results of EDS indicate that TaSi 2 can effectively fill the holes of SiC coating. There is no visible interface between the TaSi 2 outer coating and the SiC inner coating. The isothermal oxidation curve of the TaSi 2 /SiC coated carbon/carbon composites reveals that the coating can effectively protect carbon/carbon composites for 233 h at 1773 K.

A Novel Strategy for Preparation of Si-HA Coatings on C/C Composites by Chemical Liquid Vaporization Deposition/Hydrothermal Treatments.

A novel strategy for the preparation of Si-doped hydroxyapatite (Si-HA) coatings on H2O2-treated carbon/carbon composites (C/C) was developed. HA coating was prepared on C/C through chemical liquid vaporization deposition (CLVD)/hydrothermal treatment. HA coating was immersed in an H2SiO3 solution at an autoclave at 413 K for transformation into Si-HA coating. The effects of H2SiO3 mass contents on the phase, morphology, and composition of the Si-HA coatings were studied through SEM, EDS,XRD, and FTIR. Their bonding performance to C/C was measured through a scratch test. Under the optimal content condition, the in vitro skull osteoblast response behaviors of the Si-HA coating were evaluated. Results showed that SiO32− could enter into the HA lattice and occupy the PO43− sites. Doped SiO32− significantly improved the bonding performance of the HA coating to C/C in comparison with the untreated HA. The adhesive strength of the coatings initially increased and then decreased with increasing H2SiO3 content. Meanwhile, the cohesive strength of the Si-HA coatings was almost nearly identical. The Si-HA coating achieved at a content of 90% H2SiO3 exhibited the best bonding performance, and its osteoblast compatibility in vitro was superior to that of the untreated HA coating on C/C through CLVD/hydrothermal treatment.