Title: Microstructure characteristics of NiCrBSi/WC coatings on medium-Ni-Cr infinite chilled cast iron by laser cladding

Authors: Chang-jun Chen; Min Zhang; Xing Liu; Xiao-nan Wang; Yang Li

Addresses: School of Mechanical and Electrical Engineering, Laser Processing Research Center, Soochow University, Suzhou, 215021, China ' School of Mechanical and Electrical Engineering, Laser Processing Research Center, Soochow University, Suzhou, 215021, China ' School of Mechanical and Electrical Engineering, Laser Processing Research Center, Soochow University, Suzhou, 215021, China ' Shagang School of Iron and Steel, Soochow University, Suzhou, 215021, China ' School of Mechanical and Electrical Engineering, Laser Processing Research Center, Soochow University, Suzhou, 215021, China

Abstract: Thick composite coatings of tungsten carbides (WC) in a metal matrix are ideal for components subjected to heavy abrasive wear. Laser cladding NiCrBSi/WC composite layers were produced on medium-Ni-Cr infinite chilled cast iron substrates with a continuous wave (CW) CO₃ laser using the powder delivering technique. Different substrate temperature was selected during the cladding process. And the optimised preheat temperature was 300°C. Microhardness of the cladding layers was measured and the microstructure was characterised by optical microscope (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The chemical composition of the coating was analysed by the energy dispersive X-ray analysis (EDAX) equipped in the SEM machine. The results show that over 0.5 mm thickness, fully dense and crack-free cladding layers of NiCrBSi/WC can be formed on medium-Ni-Cr infinite chilled cast iron substrate. Average microhardness values of the metal matrix composite coating is as high as 900 HV, while the substrate is only 500 HV. The pin-on-plate wear tests showed the wear resistance of the cladding layer is substantially higher than that of the untreated substrate.

Keywords: nickel; chromium; silicon; infinite chilled cast iron; laser cladding; microstructure; composite coatings; abrasive wear; tungsten carbide; microhardness; metal matrix composites; MMCs; wear resistance; cladding layers; NiCrBSi coatings; superalloys.

DOI: 10.1504/IJSURFSE.2016.076513

International Journal of Surface Science and Engineering, 2016 Vol.10 No.2, pp.162 - 178

Received: 27 Mar 2014
Accepted: 20 Dec 2014
Published online: 11 May 2016 *

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