Abstract A technique to synthesize in-situ α-Al 2 O 3 composite coating on TC11 is explored for protecting titanium alloys against oxidation at high temperature. Results reveal that an oxygen barrier composite coating is formed on the substrate at 1073 K, which is composed of the compact α-Al 2 O 3 layer and transition layer. It is effective to protect TC11 from the internal and external oxidation, the oxidation rate and average oxide thickness of in-situ composite coating are much less and thinner than those of substrate. At 973 K, The rate and thickness with the composite coating are 0.01 mg 2 /cm 4 ·h and 3 μm, in comparison with 0.1 mg 2 /cm 4 ·h and 28 μm of the substrate after high temperature oxidation after 100 h. At higher temperature 1073 K, the composite coating also apparently improves the oxidation resistance (0.03 mg 2 /cm 4 ·h) compared with the non-coated substrate (7.95 mg 2 /cm 4 ·h). It was observed outward oxidation at 1073 K for the composite coating by XRD and SEM-EDS analysis, which is due to the fact that Ti diffused towards the coating surface and formed Al 2 TiO 5 . Finally, the oxidation resistance mechanism was discussed. The overall diffusion coefficient is reduced by the formation of the α-Al 2 O 3 layer. And the oxidation is inhibited by reducing substrate surface oxygen partial pressure by composite coating.

中文翻译：

---

钛合金复合涂层原位反应合成提高高温抗氧化性能

摘要 探索了一种在TC11上原位合成α-Al 2 O 3 复合涂层的技术，以保护钛合金在高温下不被氧化。结果表明，在1073 K时，基体上形成了一层由致密的α-Al 2 O 3 层和过渡层组成的氧阻隔复合涂层。有效保护TC11免受内部和外部氧化，原位复合涂层的氧化速率和平均氧化物厚度远小于基材的氧化速率和平均氧化物厚度。在973 K下，复合涂层的速率和厚度分别为0.01 mg 2 /cm 4 ·h和3 μm，而100 h高温氧化后的基体为0.1 mg 2 /cm 4 ·h和28 μm。在更高的温度 1073 K 下，复合涂层也明显提高了抗氧化性（0. 03 mg 2 /cm 4 ·h)与未涂覆的基材(7.95 mg 2 /cm 4 ·h)相比。通过XRD和SEM-EDS分析观察到复合涂层在1073 K下向外氧化，这是由于Ti向涂层表面扩散并形成Al 2 TiO 5 。最后讨论了抗氧化机理。α-Al 2 O 3 层的形成降低了总扩散系数。并通过复合涂层降低基材表面氧分压来抑制氧化。α-Al 2 O 3 层的形成降低了总扩散系数。并通过复合涂层降低基材表面氧分压来抑制氧化。α-Al 2 O 3 层的形成降低了总扩散系数。并通过复合涂层降低基材表面氧分压来抑制氧化。