Effect of Substrate Preheating on the Bonding Strength of Detonation Sprayed WC10Co4Cr Coatings

摘要

Although detonation thermal spraying is considered to be a good method for the preparation of WC-10Co4Cr coating, the depositing parameter especial the oxygen-fuel ratio observably influenced the properties of the coating. In this study a detonation thermal sprayed WC-10Co4Cr coatings were deposited on the low carbon steels substrates with no preheated and preheated 300℃, respectively. The microstructure, hardness, bonding strength, and fracture behavior of the coating were investigated by means of Field Emission Scanning Electron Microscope (FESEM), X-ray diffraction (XRD) and the pull-off pin test. The results demonstrated that with increases the temperature of substrate result in the hardness of the coating increased. The low strength of binder CoCr phase in the coating plays a decisive role in the fracture toughness of the coating. Preheating decreased the hardness of the substrate, which makes the WC particles more easily embedded in the substrate, as well as reduce the stress between the interface of the substrate and the coating which is beneficial to enhance bonding strength. Furthermore the fracture surface and particle impacting and flattening on the substrate were analyzed.