Study On Laser Cladding Wear-Resisting And Corrosion-Resistant Coating On Copper Alloy Surface

In this paper,Co,Ni,Fe based alloys,and Ta C and Ti C reinforcement phases are selected as cladding materials,laser cladding technology is used to preparation of wear resistant and corrosion resistant composite coating on copper alloy surface.Scanning electron microscope?SEM?and its supporting energy spectrum analyzer?EDS?and X-ray diffraction?XRD?were used to analyze the microstructure and phase composition of the coating.The microhardness,wear resistance and corrosion resistance of the coating were tested using a microhardness tester,a dry sliding friction and abrasion machine and an electrochemical corrosion workstation.Laser cladding Co,Ni,Fe and high molybdenum Co-based four pure metal alloy powders on the surface of copper alloys.The results show that:under the optimized process parameters,the forming quality of the Co-based and Ni-based alloy cladding layers is good,the surface of coating is flat and smooth,and there are no obvious defects such as cracks and pores;while the surface of Fe based and high molybdenum Co-based cladding layers quality is poor,there have cracks on the overlap surface,and have many pores in the bonding area.Co-based and high molybdenum Co-based alloy coatings are mainly composed of dendritic aggregated columnar crystals,and are mainly composed of fine mesh structures at the bottom of the coating;Ni-based coatings are mainly composed of fish scale phases,The area gradually transforms into fine cell-like crystals;The Fe-based alloy coating is mainly composed of a uniform network structure,and the structure gradually becomes thinner along the depth of the coating section.The hardness of the four alloy coatings are 645.5HV,469.8HV,315.3HV,and 1101.8HV,which are significantly higher than the hardness of the substrate?125.1HV?.The friction coefficient of the coating is similar to that of the substrate,mainly fluctuating between 0.32 and 0.35,but the amount of wear has been reduced to varying degrees compared to the substrate.The corrosion resistance of the four coatings has been improved to a different extent than the substrate.Co-based alloys?Stellite X-40,Tribaloy400?show the best corrosion resistance,mainly because the surface of Co-based alloys is easy to form dense oxidation.The film prevents corrosion from proceeding.In order to further improve the wear resistance and corrosion resistance of the coating,different mass fractions of Ta C/Ti C reinforcing phases are added to the Co-based alloy.When Ti C is not added,the coating is mainly composed of?-Co,Ta C,Co₃Ta,and Cr₃C₂,and the Ta C reinforcing phase is uniformly distributed in the coating in the form of particles.The upper structure of the cladding layer is mainly a typical isocellular crystal.The composition and non-directional growth,the middle and lower parts are dendritic aggregated columnar crystals,the grains gradually refine the closer to the bonding zone.When the Ta C content is 20%,the micro-hardness of the cladding layer is about 771.7 HV,which is about 6.2 times that of the substrate,and the friction coefficient is 0.303.The characteristics of cooling and cooling can play a role in refining the grains,and Co atoms easily combine with Ta atoms to form Co₃Ta intermetallic compounds.The uniform distribution of Ta C reinforcing phase and Co₃Ta intermetallic compounds in the coating effectively improves the hardness of the coating And abrasion resistance.And the corrosion resistance of the coating is significantly improved.This is mainly due to the formation of Ta₂O₅ oxide during the oxidation process.Ta₂O₅ has a high resistance to Cl ions and is not easily replaced by Cl ions in the solution.With the addition of Ti C reinforcing phase,new uniformly distributed round particles aggregated into dendritic phases appeared in the cladding layer,which are mainly Ti C reinforcing phase and Co₃Ti intermetallic compound.The hardness and corrosion resistance of the cladding layer increase with the increase of the Ti C content.When the Ti C content is 15%,the hardness of the coating is 898.4HV,which is about 7.2 times that of the substrate.The corrosion resistance is the best,but its resistance to corrosion The abrasiveness is lower than when Ti C is 10%.This is because the high content of the ceramic phase affects the metallurgical bonding performance of the molten pool,which causes the reinforcing phase to fall off easily and reduce the wear resistance.When the Ti C content is 10%,the coating has the best abrasion resistance and shows good corrosion resistance.