Tribology International xxx (xxxx) xxx Please cite this article as: Peiying Shi, Tribology International, https://doi.org/10.1016/j.triboint.2020.106759 Available online 4 November 2020 0301-679X/© 2020 Elsevier Ltd. All rights reserved. High temperature tribological performance of nickel-based composite coatings by incorporating multiple oxides (TiO 2 –ZnO–MoO 3 ) Peiying Shi a, b , Gewen Yi a, b , Shanhong Wan a, b, * , Huwei Sun a, b , Xiaochun Feng a, b , Sang T. Pham c , Kiet A. Tieu c , Erqing Xie d , Qihua Wang a, b, ** a State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000, PR China b Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, PR China c Faculty of Engineering and Information Sciences, University of Wollongong, Wollongong, NSW, 2522, Australia d School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000, PR China A R T I C L E INFO Keywords: Composite coatings High temperature tribology Atmospheric plasma spray Oxides ABSTRACT The potential of lower friction and desired wear for nickel-based composite coating system at high temperatures was explored, where multiple oxides were incorporated into nickel matrix during the atmospheric plasma spraying process. The phase composition and microstructure of wear track were characterized by XRD, Raman, SEM/EDS, and FIB/STEM. The further addition of MoO 3 allows for an effective reduction of friction coeffcient at 800 ◦ C. The surfcial and interfacial analysis well confrmed that a protective tribo-layer presenting on the contacting surface, in which binary oxides (A-TiO 2 , R–TiO 2 , ZnO, NiO), molybdates and titanates (ZnMoO 4 , NiMoO 4 , and Zn 2 TiO 4 ) were identifable. The association of friction and wear properties with interface chemistry was discussed for the nickel-based coatings with the addition of multiple oxides (TiO 2 –ZnO–MoO 3 ). 1. Introduction Ternary and binary oxide phases are always added in bulk materials directly by powder metallurgy or deposited as coatings, and they have been widely studied as high temperature lubricants [1]. It has been revealed that the synergistic effect of binary oxides and newly in-situ formed ternary oxides plays the dominant role in improving tribological properties [2–6]. For example, ternary oxides like silver molybdates (Ag 2 MoO 4 , Ag 2 Mo 2 O 7 , and Ag 2 Mo 4 O 13 ) have inherently lamellar structure and thereby, are very lubricious [7–9]. As highlighted that, the Mo–Ag–O system renders excellent lubricating performance from 350 ◦ C to 600 ◦ C, which has been reported to be associated with high temper- ature reaction, tribo-chemical processes, sublimation or melting [10–12]. Considering the melting temperature, Ag 2 Mo 2 O 7 is stable up to 400 ◦ C and will segregate into MoO 3 and Ag from 400 ◦ C to 500 ◦ C [9]; The eutectic mixture of Ag 2 Mo 4 O 13 and Ag 2 Mo 2 O 7 has the melting temperature of about 508 ◦ C, while the melting temperature of another eutectic mixture of Ag 2 Mo 2 O 7 and Ag 2 MoO 4 is 496 ◦ C [13]. The tribological properties of binary oxides systems have also been studied, e.g. MoO 3 –PbO, MoO 3 –CuO, MoO 3 –NiO, and MoO 3 –ZnO sys- tem [14–19]. In comparison, CuMoO 4 , Cu 3 Mo 2 O 9 and ZnMoO 4 com- pounds have a relatively higher melting point, about 820 ◦ C, 855 ◦ C, and 1003 ◦ C, respectively [20–22]. Ouyang et al. fabricated self-lubricating NiCr–BaMoO 4 composites by powder metallurgy method with friction coeffcients less than 0.30 at high temperatures [2]. Nickel-based coat- ings containing nanostructured TiO 2 /Bi 2 O 3 exhibited excellent tribo- logical behavior with the friction coeffcient of 0.07 at 800 ◦ C, which was attributed to the synergistic effect of ternary oxides (Bi 4 Ti 3 O 12 and NiTiO 3 ) and binary oxides (TiO 2 and NiO) on the worn surfaces [3]. Moreover, T.W. Scharf et al. [4,23] found that ZnTiO 3 with the (104) stacking faults was able to be sheared parallelly to the sliding direction and thus atomic layer deposition ZnTiO 3 coating displayed better tribological performance. Very recently, Ni–5wt.%Al/TiO 2 –ZnO coat- ings were prepared by atmospheric plasma spraying (APS), the improvement in tribological performance of nickel-based matrix attained as the temperature exceeds 600 ◦ C [24]. * Corresponding author. State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000, PR China. ** Corresponding author. State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, P. R. China. E-mail addresses: shwan@licp.cas.cn (S. Wan), wangqh@licp.cas.cn (Q. Wang). Contents lists available at ScienceDirect Tribology International journal homepage: http://www.elsevier.com/locate/triboint https://doi.org/10.1016/j.triboint.2020.106759 Received 2 September 2020; Received in revised form 24 October 2020; Accepted 1 November 2020