Ablation mechanism of TaC coating fabricated by chemical vapor deposition on carbon-carbon composites

摘要：

Ablation characteristics and mechanism at high temperature for TaC coatings on carbon-carbon composites were investigated by ablation experiments with low power laser and oxyacetylene flame. The results show that the TaC coating is decomposed at the initial stage of laser ablation in atmosphere, and free carbon diffused to the surface, then oxidized to the melt including carbon, oxygen and tantalum. With the increase of ablation time, the melt is oxidized to low valent tantalum-oxide and ta2O5 is formed finally. During the melt cooling, needle-like crystals of Ta2O5 are precipitated. Between the melt and TaC coating, there exists a diffusion transition layer with thickness of 1-2 um. The transition layer consists of fine crystals and pores including carbon, oxygen and tantalum. The oxyacetylene flame ablation at 2 300 ℃ results in the rapid oxidation of TaC and formation of protective liquid films of tantalum oxide on the coating surface, where the liquid film can fill up the cracks and cover the coating. In such case, the oxidation mechanism of TaC is converted to the oxygen solution and diffusion control mechanism.

关键词： TaC coating ozidation ablation mechanism carbon-carbon composites

作者: LI Guo-dong XIONG Xiang HUANG Ke-long

作者单位: State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China School o State Key Laboratory of Powder Metallurgy, Central South University,Changsha 410083, China School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China

会议类型: 国际会议

会议名称: 2009 Frontier Symposium of China Postductors on Materrials Science(2009年中国博士后材料科学前言论坛)

会议地点: 长沙

会议语种:英文

页码: 689-695

在线出版日期: 2009-11-22（万方平台首次上网日期，不代表论文的发表时间）