真空退火对TC4钛合金表面Ti/TiN多层复合涂层性能的影响

Effect of Vacuum Annealing on Properties of Ti/TiN Composite Coating Deposited on TC4 Titanium Alloy

摘要:

金属基体材料表面硬质膜层在服役过程中,残余应力在膜基界面以及膜层内部界面之间的积聚会导致膜层发生界面剥落失效。以TC4钛合金基体表面Ti/TiN多层复合膜层为研究对象,探讨真空退火对复合膜层结构及性能的影响,并表征退火前后复合膜层的界面划痕失效以及抗粒子冲蚀性能。结果表明,真空退火促进了膜层内部以及膜基界面两侧原子的热扩散,使得界面结构特征明显弱化。界面状态的改变使得复合膜层的表面显微硬度降低以及膜基结合强度提高。在划痕载荷作用下,复合膜层抵抗裂纹沿界面扩展的能力得到增强。真空退火有助于提高膜层的强韧性匹配,可有效抵抗小角度冲蚀粒子的犁削以及大角度粒子冲蚀下的疲劳,因此Ti/TiN多层复合膜层表现出较好的抗冲蚀性能。

Abstract:

Hard coatings deposited on metal substrates often occur crack and delamitation due to the higher residual stress accumulated on the interface of coating/substrate and also the inside of the coating. The effect of vacuum annealing on multilayered Ti/TiN coating deposited on TC4 titanium alloy substrate was studied in detail. Also the interface cracks under scratch load and sand erosion resistance were characterized. The results show that a multilayered Ti/TiN coating with weakened interface characteristic is obtained due the atoms diffusion on both side of the interface,which results in a decrease of hardness and increase of bonding strength. At the scratch load,the resistance of crack expansion along the interface is strengthened. And also the sand particles' "micro cutting"at small angle and fatigue effect at higher angle are restrained,so the sand erosion resistant of the annealed Ti/TiN coating is reinforced.