| Thermal spraying technology is usually used to spray one or more functional materials on the surface of aviation superalloy parts,so as to give consideration to wear resistance and corrosion resistance on the basis of high strength,low specific gravity and high thermal conductivity[1].Thermal spraying technology has the characteristics of high deposition efficiency,high production efficiency and a wide range of spraying materials,but the coating interior often presents a typical layered structure,and the coating is bonded mechanically with low strength.There are also many pores and microcracks in the coating,which together lead to the decrease of the coating compactness and wear resistance,affect the service performance and reduce the service life.For this phenomenon,laser assisted thermal spraying technology is usually used to eliminate the defects of thermal spraying coatings.Laser assisted thermal spraying adopts laser as heat source to remelt or soften the coating,which can effectively reduce or eliminate the pores and microcracks of the coating,eliminate the stratification phenomenon,greatly improve the densification and wear resistance of the coating,and improve the structure and performance of the thermal spraying coating.In this paper,based on the research of plasma spraying superalloy coating,Ni Cr coating material was sprayed on GH625 superalloy substrate surface as the research object,and the influence of laser-assisted thermal spraying process parameters on the improvement of coating microstructure and performance was discussed.At the same time,the finite element model was established and the influence of laser parameters on the temperature field was discussed by ANSYS simulation technology.The results show that the coating quality is the best under the experimental parameters of 600W power,50mm/s scanning speed and 0.3 overlap rate.The results of metallographic analysis and scanning electron microscopy showed that compared with the original plasma spraying coating,the non-molten particles on the surface and inside of the laser-assisted coating disappeared,and the number of pore microcracks was greatly reduced.According to the XRD phase detection,EDS scanning and other technical means,it was found that the coating had uniform internal structure,no phase change,and the thermal influence area of matrix was small.Compared with plasma spraying,the porosity of the coating decreased from 6.61to0.66,the average hardness increased from Hv0.2=613.00 to Hv0.2=863.34,and the bonding force method becomes metallurgical bonding.A variety of detection and research methods are adopted to analyze the role of technological parameters in the remelting process,which also lays a theoretical foundation for the wider application of laser-assisted thermal spraying technology in the field of high-temperature alloy coating in the future. |
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