Wear Behavior of Ni-base Composite Coating With Directional Solidification Structure

The composite 20%WC+Ni and 5%G+20%WC+Ni coatings were prepared by vacuum cladding method on the ZG45 substrate.Microstructures,forming mechanism for the coatings and the tribological properties were investigated.The results show that the microstructure of composite coating is dense,and there are not any inclusion and pores at the interface of the coating and substrate.The main composition of coating is Ni-based solid solution and hard intermetalic compounds.The major influential factor of the isomeric microstructure is the directional solidification during metal solidification.The wear results show that the friction coefficient and fluctuation of friction coefficient of 5%G + 20%WC+ Ni coating are lower than that of 20%WC + Ni coating for the same wearing testing parameters.The wear rate of 20%WC + Ni coating increases with the increasing wear frequency,whereas the wear rate of 5%G + 20% WC + Ni coating decreases with the increasing wear frequency.The abrasive wear and oxidation wear dominate the wearing process of 20%WC + Ni coating,and the oxidation wear and micro-crack lamellar for 5%G+20%WC+Ni coating.