Microstructure and wear behaviour of Ni-based alloy coated onto grey cast iron using a multi-step induction cladding process

The purpose of this work was to develop an innovative approach to remanufacturing grey cast iron cylinder liners. Ni-based alloy coatings were fabricated on HT 300 cast iron substrates using a multi-step induction cladding technique. Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and X-ray Diffraction (XRD) were employed to analyse the microstructure, elemental distribution and phase composition of the coating. The results indicated that the coatings were metallurgically bonded to the substrate, and there were no visible defects and cracks at the interface resulting in failure of the coating. The portion closest to the substrate was rich in γ-Ni solid solution, whereas the intermediate and top portions consisted of boride-, carbide- and Ni-based solid solution eutectics. The microhardness from the top layer of the coating to the interface exhibited a gradual decrease, and the average microhardness of the coating is 877.12 HV0.2, which was four times higher than that of the substrate. The results of dry sliding wear tests showed that the friction coefficient of the Ni-based alloy coating was much more consistent than that of the HT 300 substrate, and the wear loss and roughness of the coating was lower than that of the substrate. The wear mechanism for the coating is light abrasive wear, whereas for the substrate, the wear mechanism is a mixture of severe abrasive and adhesive wear.