Growth And Mechanical Properties Of WC Coating Prepared By Solid Phase Diffusion

Poor hardness and wear resistance make the surface of gray cast iron prone to failure,which can not satify the current industry requirements for its performance.In order to strengthen the surface of gray cast iron and obtain good comprehensive mechanical properties,the solid phase diffusion method was used to prepare iron-based surface tungsten carbide coating at 1000°C,1050°C and 1100°C for 1 h,2 h,3 h,4 h and 5 h,respectively.Base surface tungsten carbide coating to improve the surface quality of gray cast iron.In this paper,the phase composition of WC coating is firstly analyzed by XRD to explore the change of phase composition with temperature.SEM was used to characterize the changes of WC coating thickness and microstructure with temperature and holding time,and EBSD technology was combined to analyze WC grain orientation,average grain size and structure of W/WC interface;Based on classical kinetic theory,calculate the growth rate constant of the WC coating.Secondly,the hardness,elastic modulus and fracture toughness of WC coatings at 1050°C and1100°C were evaluated by nano-indentationand micro-indentation techniques under the load of 0.98 N?4.90 N.The toughening mechanism was investigated.Finally,the friction and wear properties of the Fe and WC coatings at room temperature and dry wear were investigated by ball-disk wear test under the load of 5?20 N.The damage characteristics and wear mechanism of the wear surface were analyzed.The results show that:(1)Temperature is the main factor for WC coating thickening,the maximum thickness is up to 190.77?m,W/WC interface is W₂C and Fe₃W₃C,respectively;(2)WC coating has high hardness and good fracture.The toughness and toughening mechanism are crack deflection,crack branching,crack bridging and transgranular fracture.(3)The wear resistance of WC coating is about 1.4 to 2.6 times that of matrix Fe.The wear mechanism is abrasive wear,oxidative wear and fatigue wear.