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nzhen Wang and Junhong Jiaa) State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, People’s Republic of China (Received 20 March 2016; accepted 13 September 2016)

Ni-based composites with in situ formed Al2O3 and TiC ceramic phases were fabricated by hot pressing technology and that with directly added Al2O3 and TiC particles (ex situ) were also fabricated for comparison. The antioxygenic property and tribological properties of the composites were comparatively studied. The results show that the high-temperature oxidation resistance of the composite with in situ formed Al2O3 and TiC ceramic is superior to that of ex situ composite, and the friction coefficient of in situ composite is lower than that of ex situ composite in the wide temperature range from 400 °C to 1000 °C. The lowest friction coefficient was about 0.19 at 1000 °C and the wear rate of the composites are in the order of magnitude of 10
6 mm3/(N m) at high temperatures. The differences in tribological properties of in situ/ex situ composites are attributed to the formation of the glaze layer composed of MoO3, TiO2, Al2TiO5, NiAl2O4, and NiO on the worn surfaces and the difference of the distribution of the ceramics in the matrix.

I. INTRODUCTION

High temperature oxidation and lubrication used in special conditions is still a great subject and significant challenge to the Materials Science and Engineering as well as tribology community.1–3 Metal matrix composites (MMCs) constitute an important class of materials for tribological applications.4 As a kind of representative and very promising MMCs, Ni-based composites are well known for their various properties such as prompt thermal stability and excellent anticorrosion and wear resistance.5–7 But the high temperature wear is still the major technical limitation factor for a wide use of Nibased composites in the tribology system.8–10 To improve the wear resistance properties of Ni-based composites at elevated temperature, the addition of a relatively small amount of ceramic phases to the nickel alloy matrix can remarkably improve the characteristics of the alloy due to the synergetic effect of hard ceramic reinforcements and the matrix. Among ceramic particulates, TiC and Al2O3 have high melting points (.2000 °C), high hardness (.2000 Hv), good thermal stability, notable corrosion, and erosion resistance, as well as excellent wear Contributing Editor: Jürgen Eckert a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2016.350

resistance. Those outstanding features make them have potential prospects for tribological applications especially as constituents of a multi-component protective coating or composites to enhance resistance against thermal and mechanical wear.11–15 Tian et al. had prepared Ni–Al2O3 nanocomposite coating by electrophoretic-electroplating deposition displayed a better wear resistance property than pure Ni coating.16 Lu et al. studied and analyzed the tribological behaviors of a