为了提高GH05高温合金在高温高压水环境下的摩擦性能，在合金表面采用离子源辅助非平衡磁控溅射和多弧离子镀方法分别制备了Cr/DLC 和CrN 2种涂层。采用FGD高压釜对涂层进行高温高压试验，采用扫描电子显微镜(SEM)观察涂层表面及截面形貌，采用 UMT 高温摩擦磨损试验机、台阶仪、纳米压痕仪分别研究了2种涂层高温高压试验前后的摩擦磨损性能、硬度和弹性模量。结果表明：高温高压试验后，CrN涂层的表面形貌和力学性能相较于高温高压前的CrN样品而言变化较小；但Cr/DLC涂层发生了明显的氧化，涂层结构疏松，结合力和硬度显著降低。另一方面，高温高压试验致使Cr/DLC涂层和CrN涂层在干摩擦和水环境下的摩擦系数均升高，可能是由于涂层表面发生了氧化及力学性能劣化。相比于Cr/DLC涂层摩擦性能的急剧下降，CrN涂层经过高温高压试验仍能保持较好的摩擦磨损性能；特别地，CrN 涂层在水环境下的磨损率低至1.40 × 10-7 mm3/(N·m)，仅为相同试验条件下Cr/DLC涂层磨损率[8.73× 10-6 mm3/(N·m)]的1.60%，CrN涂层大幅提升了高温合金在苛刻工况下的服役性能。
For improving the friction properties of GH05 superalloy in high temperature and high pressure water environment, Cr/DLC and CrN coatings were prepared on the alloy surface via ion source assisted unbalanced magnetron sputtering and multi - arc ion plating respectively. FGD autoclave was used to conduct the high temperature and high pressure test of the coatings, and scanning electron microscope (SEM) was used to observe the surfaces and cross - sectional morphologies of the coatings. Moreover, a high temperature UMT tribometer and a step height tester were used to study the friction and wear properties of the coatings, and a nanoindenter was employed to measure the hardness and elastic modulus of the two kinds of coatings before and after high temperature and high pressure test. Results showed that the surface morphology and mechanical properties of the CrN coating after high temperature and high pressure test changed slightly in comparison with that before such test. However, the Cr/DLC coating suffered remarkable oxidation. The coating structure became loose, and the bonding force as well as the hardness of the coating significantly decreased. On the other hand, the high temperature and high pressure test led to an increase of the friction coefficient of Cr/DLC and CrN coatings in both dry and water environments, which might be attributed to the oxidation of the coatings’ surfaces and the deterioration of mechanical properties of the coatings. Compared with the sharp decrease of friction properties for the Cr/DLC coating, CrN coating still maintained good friction and wear properties after high temperature and high pressure test. Especially, the wear rate of CrN coating in water environment was only 1.40 × 10-7 mm3/N·m, which was only 1.60% of that of the Cr/DLC coating under the same test condition (i.e., 8.73× 10-6 mm3/N·m). Overall, the CrN coating could greatly improve the service performance of the superalloy under severe working conditions.
