Research On Plasma Sprayed T800 Co-based Coating

T800 alloy has excellent wear resistance,high temperature resistance and corrosion resistance.At present,the application of T800 Co-based alloy coating to strengthen material surface has not been reported.In this study,T800 Co-based alloy coating was prepared by plasma spraying technique,and the plasma spraying parameters were optimized.By using X-ray diffraction?XRD?,Scanning Electron Microscope?SEM?,the microstructure and morphology of T800 coating were characterized,while the high temperature resistance,mechanical properties and friction and wear properties of the coating were tested.The main research contents and results are as follows:By studying the effects of different spraying power and spray distance on the T800coating,results show that:when the spraying power is 30kW and the spraying distance is100mm,T800 coating mainly composes of Co based solid solution and Co₃Mo₂Si,the structure of T800 coating is lamellar and compact,which has low porosity.The hardness dispersion of the coating is the lowest,and the average hardness is the highest,which is556.27HV_0.1.By studying the thermal stability of T800 coating.T800 coating has excellent oxidation resistance,the oxidation of coating does not occur at 400?-600?,when heating temperature is more than 600?,Mo of coating is oxidized into MoO₃,T800 coating is still mainly composed of Co-based solid solution and Co₃Mo₂Si.The hardness of T800 coating increases firstly and then decreases with the increasing of temperature,and the hardness of the coating reaches the maximum at 600?,which is about 759.52+HV_0.1.Through analysis of the fracture surface of coating,it is found that the original coating has excellent toughness,and the toughness decreases at 600?,and the brittle fracture occurs.T800 coating has good wear resistance at room temperature,the coating have micro cutting and plowing under low load,the wear mechanism is main abrasive wear,when load is high,the coating produces micro cracks and fracture,the wear mechanism is main local shedding;T800 coating have good wear resistance at 400?,the friction coefficient of T800coating at 400?is much less than the coefficient of friction at room temperature,the main reason is:the friction surface forms lubricating film at high temperature,the surface roughness is low,the coating has obvious plough at high temperature,furrow depth deepen,the main wear mechanism is abrasive wear.According to the analysis of the wear surface,the friction surface of T800 coating is easy to be oxidized at high temperature.