Wear 259 (2005) 801–806 Short communication Sliding wear behaviour of laser clad coatings based upon a nickel-based self-fluxing alloy co-deposited with conventional and nanostructured tungsten carbide–cobalt hardmetals H. Chen a,∗ , C. Xu a , J. Qu a , I.M. Hutchings b , P.H. Shipway c , J. Liu d a Department of Materials Science and Engineering, School of Mechanical and Electrical Engineering, China University of Mining and Technology (Beijing), D11 Xue Yuan Lu, Beijing 100083, China b Institute for Manufacturing, Department of Engineering, University of Cambridge, Mill Lane, Cambridge CB2 1RX, UK c School of Mechanical, Materials and Manufacturing Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK d Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China Received 27 September 2004; received in revised form 7 January 2005; accepted 7 February 2005 Available online 10 May 2005 Abstract Nickel-based self-fluxing alloys (SFA) have been widely used as coatings in the light of their high levels of wear and corrosion resistance. However, their resistance to wear can be substantially improved by reinforcement with tungsten carbide–cobalt hardmetals. In this work, a range of coatings based on a nickel-based self-fluxing alloy has been produced by laser cladding. The coatings have been reinforced with both conventional and nanostructured WC–Co at a single level of 30 wt.%. The effect of ceria as a grain refiner has also been examined. The sliding wear behaviour of the coatings was examined in a block on ring apparatus and the temperature of the samples measured during the wear tests. In all cases, the addition of WC–Co to the base alloy resulted in a significant increase in wear resistance, with wear rates of the reinforced deposits being less than 10% of that of the unreinforced deposit. The coating reinforced with a mixture of conventional and nanostructured WC–Co exhibited the lowest rates of wear. The addition of ceria was shown to significantly refine the microstructure of the deposit; however, little change was observed in the wear behaviour of the resulting material. © 2005 Elsevier B.V. All rights reserved. Keywords: Laser cladding; Nanocomposite; WC–Co; Cermet 1. Introduction Nickel-based self-fluxing alloy (SFA) coatings have been used in a wide range of industrial applications on account of their combination of high wear and corrosion resistance. SFAs are a group of alloys with a wide range of composi- tions; nickel-based SFAs commonly contain chromium, iron, boron, silicon and carbon as alloying elements (often with boron and carbon contents of up to around 4 and 1 wt.%, respectively) [1]. Coatings based upon such an SFA compo- sition will typically consist of a nickel-based metallic matrix ( phase) with a range of nickel-, chromium- and iron-based ∗ Corresponding author. E-mail address: camchh@yahoo.com (H. Chen). borides and carbides [1–3]. Due to the high proportions of these hard phases, the Vickers hardness of such coatings of- ten exceeds 700 kgf mm −2 [1,4,5]. However, in many environments, SFA coatings cannot provide sufficient resistance to wear and consequently, re- inforcement of the alloys by co-depositing a hard cermet phase has been attempted; the hard cermet phase employed is commonly a tungsten carbide-based hardmetal (WCHM). It has been demonstrated that such composite coatings can offer enhanced wear resistance which is achieved by com- bining the relative toughness of the SFA with the hardness of the WCHM [5–7]. Moreover, they are able to offer wear resistance in environments where oxidation resistance is also required [8]. Coatings of this type have been deposited by a variety of methods such as vacuum brazing [9], laser cladding 0043-1648/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.wear.2005.02.066