Effect of WC content on hardness and fracture toughness of WC-Ni60A wear-resistant coatings

Abstract

WC-Ni60A is widely used in surface wear-resistant parts, its toughness has a significant effect on its performance, but the related research is less. The plasma cladding method was used to successfully cover 45# steel substrates with three different types of WC-Ni60A coatings that are highly resistant to wear. The coatings had different amounts of WC. Field emission scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffractometry (XRD) were used to analyze the wear-resistant coatings' microstructure, elemental distribution, and phase composition. A micro-Vickers hardness tester and a nanoindentation tester were used to measure the coatings' microhardness and nanohardness. They were also tested for their ability to resist plastic deformation and recover from elastic deformation. Finally, the fracture toughness of the coating was studied utilizing a three-point bending test combined with numerical simulation to demonstrate the crack extension process. The metallurgical bonding of the three prepared coatings with the substrate is excellent. The hardness of the coatings increased as the WC content grew, reaching a maximum microhardness of 1038.75 HV. However, the fracture toughness reduced as the WC content increased, and the fracture modes were also transformed. The fracture toughness values for the 15 %, 25 %, and 35 % WC-Ni60A coatings were measured as 35.57, 34.54, and 31.395 $\mathrm{MPa}\sqrt{m}$, respectively. The crack toughness values that the finite element model predicted for the 15 % and 25 % WC-Ni60A coatings were 34.86 and 32.56 $\mathrm{MPa}\sqrt{m}$, which were 2 % and 5.8 % lower than the experimental data.