Study On Microstructure And Properties Of Nickel Based WC Particles Reinforced Composite Coatings By Plasma Spray Welding

The progress of modern science and technology requires materials,which combines a number of functions to meet the needs of modern society,must keep pace with the times.The wear and corrosion of metal materials is the main form of failure,thus improving the wear and corrosion resistance of materials is of great significance.The Plasma Spray Welding technology was apllied in this paper.By changing the content of WC and the parameters of welding current,the Ni-based Plasma Spray Welding of WC particle reinforced coatings were prepared.We obtained the effects of WC content and the spray welding current on the properties of the coating through the measurement and analysis of coating hardness,friction and wear properties and corrosion resistance and combined with detection of micro structure characterized by XRD,SEM and EDS.The results were analyzed and interpreted.The coatings prepared in the experiment shows a metallurgical combination and the coatings combine with the base very well.WC changed the composition phase of Ni-based self-fluxing alloy coatings as the emergence of Cr carbide in Ni-Cr-Fe,Ni-Cr-Fe-C,CrB,SiC,Cr,.3C6.At the same time,WC makes black and gray striped CrB gradually reduced or disappeared.And with the increasing of the content of WC,W2C become more and longer and changing from point to the strip and fishbone due to its influence on the energy.Spray welding currents have an impact on the microstructure of spray welding layers.With the increasing of current,the morphology of WC particles changes from irregular to spherical and W2C shows a decreasing trend and W2C near the surface grows shorter.The effects of the addition of WC on hardness do not have infinite positive correlation.In a certain concentration range(Ni+40%WC),it can significantly increase the hardness and the average hardness is up to 4.5 times of the matrix.If its content exceeds a range,the correlation is decreased.It has the same rules for the tribological properties and hardness,showing the relevance of hardness and wear properties.Certain content of the addition of WC will improve the corrosion resistance of Ni-based coatings,but the excessive addition of WC(Ni+50%WC)will affect its corrosion resistance in electrochemical performance of the coatings,closely relating to the number and inner grain boundary in the coatings.The influence of current on the performance of the coating significantly.The hardness reaches the maximum and with excellent corrosion resistance and tribological properties when the current is 110 A.When the currents are less than 110 A,powder cannot be completely melted,showing low density;When the current is higher than 110 A,heat exchange increased,porosity and other defects appear in the coating,WC partial dissolution enhancement weakened,therefor the performance cannot achieve optimally.