γ-TiAl合金表面Al2O3/Al复合涂层的抗高温熔盐腐蚀性能研究

Enhanced high temperature corrosion resistance of Al2O3/Alcomposite coating on γ-TiAl alloy

摘要:

采用磁控溅射技术于γ-TiAl合金表面制备Al₂O₃/Al复合涂层。在850 °C下、 100 wt.% Na₂SO₄熔盐中观测Al₂O₃/Al复合涂层的高温腐蚀行为。结果表明,Al₂O₃/Al复合涂层具备由Al₂O₃表层、富Al中间层以及互扩散层组成的梯度结构,因而有效地提高了基体γ-TiAl合金的抗高温腐蚀性能。在腐蚀实验后,涂层试样表面相结构为Al₂O₃,TiO₂和TiAl₃。致密的Al₂O₃/Al复合涂层有效地抑制了O_2-,S_-和Na₊对基体γ-TiAl合金的侵蚀。并且,Al₂O₃/Al复合涂层的梯度结构亦使其表现出了优异的抗开裂和抗剥落性能。

Abstract:

γ-TiAl specimens were coated with an Al₂O₃/Al composite coating using magnetron sputtering. The corrosion resistance of the coated specimens were investigated in molten salt environment of 100 wt.% Na₂SO₄at 850 °C. Al₂O₃/Al composite coating improved the high temperature corrosion resistance of γ-TiAl alloy effectively. This good resistance was attributable to the gradient structure of Al₂O₃/Al composite coating which consist of an Al₂O₃ top-layer, an Al-rich interlayer and a diffusion layer. The results of corrosion test revealed that the Al₂O₃, TiO₂ and TiAl₃ were identified as the main phase structure of the corroded coating surface. Moreover, the sealed coating structure could effectively suppress the erosion of O_2-, S_- and Na₊, while Al₂O₃/Al coating with gradient structure exhibited superior crack and spallation resistance.