Elucidating friction properties and strengthening mechanisms of Ni-based surfacing layer containing 9R phase

• Published in: Surface & coatings technology Vol. 468; p. 129751
• Main Authors: Zhang, Le, Xiong, Jiankun, Li, Yang, Xu, Jian, Li, Xue, Zhang, Haibo, Chen, Zhuo, Yang, Jianping, Ou, Wuxing, Mao, Guijun, Li, Ting, Nie, Fuheng, Yuan, Xinjian
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.09.2023
• Subjects: 9R phase; Anti-wear surfacing layer; Friction properties; Gradient nanostructure; PTA-surfacing; Anti-wear surfacing layer; PTA-surfacing; 9R phase; Friction properties; Gradient nanostructure
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2023.129751

This study analyzed the strengthening mechanisms and friction properties of Inconel 625 surfacing layers fabricated by plasma transfer arc surfacing (PTA-surfacing) in ball-on-disc friction tests at room temperature and 650 °C. Results showed that Inconel 625 exhibited poor tribological performance at room temperature, but excellent at 650 °C. The average Vickers hardness of the high-temperature wear area (1.6826 ± 0.4059 GPa) was higher than that of the room temperature wear area (1.3900 ± 0.1875 GPa). The coefficient of friction for Inconel 625 decreased from 0.5362 at room temperature to 0.2846 at 650 °C. The wear rates of Inconel 625 at 650 °C and room temperature were 1.2063 × 10−5 mm3/N·m and 20.9740 × 10−5 mm3/N·m, respectively. The wear mechanisms at 650 °C were mainly abrasive, adhesion, oxidation wear, and some degree of delamination wear. The microstructural characterizations revealed that the wear subsurface at 650 °C comprised polycrystalline-mixed oxide layers (Ni(Cr,Fe)2O4, (Cr,Fe)2O3, and NiO), gradient grain refinement, nanoscale precipitations (M23C6, M6C, and laves), 9R structural phases, I-type twinning, and high-density dislocations, which synergistically enhance the outstanding high-temperature friction properties and strength. •Crack-free Ni-based coatings were fabricated by PTA-surfacing.•The Inconel 625 coating exhibits outstanding friction properties at 650 °C.•Deformed twinning mechanism under wear subsurface was identified as I-type twinning.•ABCBCACAB-type 9R phase originating from ITBs at wear subsurface is discussed.•Strengthening mechanism and its relationship with tribological performance are revealed.