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Abstract: To prevent carbon/carbon composites from oxidation at 1773 K, an efficient oxidation protective glass coating has been prepared on the surface of SiC coated C/C composites by a simple and low-cost method. The microstructures and phase composition of the as-prepared coating were examined by SEM and XRD. Oxidation testing shows, after oxidation in air at 1773 K for 140 h and thermal cycling between 1773 K and room temperature for 8 times, the weight loss of the coated sample is only 0.98%. The oxidation of the coated C/C composites is attributed to the formation of bubble holes on the coating surface and microcracks in the coating. [Copyright &y& Elsevier]

Abstract: In this work, the network structure of ZrO2 nanorods was firstly synthesized without a metal catalyst. A developed vapor–liquid–solid (VLS) and oxide-assisted growth (OAG) model is discussed as the growth mechanism of ZrO2 nanorods. ZrO2 nanoparticles, as a growth catalyst, provide zirconium and oxygen atoms for the formation of the nanorods and serve as a growth site as well. In the center and transition regions, ZrO2 nanorods with a diameter of 30–54nm finally grow into a network of ZrO2 layer during the cooling process. In the border region, due to the appropriate growth temperature and adequate ZrO2 vapors, ZrO2 nanorods with a significant increase in length are synthesized during the ablation process. [Copyright &y& Elsevier]

Abstract: In order to improve the ablation resistance of carbon/carbon (C/C) composites, a ZrC nanostructured coating was prepared on C/C composites by chemical vapor deposition. Results show that the coating contains ZrC grains with the size of 20–30nm and the structure displays a high consistent orientation. This nanostructured coating has improvements in linear and mass ablation rates of 50.7% and 42.1% compared with those of the conventional ZrC coating. The good ablation resistance could be attributed to the efficient prevention of the coating cracking and the formation of the dense ZrO2 layer during ablation. [Copyright &y& Elsevier]

A new type of oxidation-protective multi-composition coating for carbon/carbon (C/C) composites has been produced by a pack cementation technique in an argon atmosphere. XRD analyses shows that the phases of the composite coating are composed of Al2O3, mullite, SiC and Al4SiC4, and the bonding layer between the coating and C/C composites are composed of Al4C3, SiC and Al4SiC4. It is found by SEM surface observation and EDS area scanning analyses that the coating has two kinds of surfaces that are distinctly different in element content of Si and C. In the meantime, cross-section SEM observation of the coating also displays a dense microstructure. Oxidation test shows that the as-prepared coating characterized by excellent thermal shock resistance on the surface of C/C composites during exposure to an oxidizing atmosphere at 1773 K could effectively protect the C/C composites from oxidation for 41 h. [Copyright &y& Elsevier]