Laser Cladding Process Of TC4 Surface Based On Wear Resistance And High Temperature Oxidation Resistance

In order to expand the application range of TC4 titanium alloy and improve its surface wear resistance and high temperature oxidation resistance.Ni Cr Co Al Y/Cr₃C₂mixed powder was used as cladding powder.The composite coating with excellent performance was prepared on TC4 titanium alloy surface by laser cladding technology.The laser cladding process parameters were optimized by single pass single factor and multi pass overlapping laser cladding test.The macro morphology,microstructure and phase composition of the coating were analyzed by OM,SEM,EDS and XRD.Microhardness tester,wear tester and intelligent muffle furnace were used to test and analyze the wear resistance and high temperature oxidation resistance of the cladding layer.The conclusion is as follows:Through single pass single factor,orthogonal and overlap test,the best process parameters were obtained as follows:laser power is 600W,scanning speed is 3mm/s,powder feeding rate is 1r/min,defocusing amount is 0,overlap ratio is 30%,and good quality cladding layer without cracks and pores were fabricatedObservation of the cladding layer by SEM showed that the cladding layer and the matrix have formed a good metallurgical bond,and there are a large number of plane crystals,cellular crystals and equiaxed crystals at the bottom of the molten pool,and the inside of the cladding layer is composed of a large number of The dendrites,needle-like crystals and dendrite-like structures.Through EDS and XRD testing and analysis of the elements and phases of its structure,it can be concluded that the various microstructures generated inside the cladding layer contain a large number of ceramic carbides such as Cr₇C₃,Ti C and a large number of intermetallic compounds such Cr₃Ni₂,Cr₂Ti,Ni₃Ti,Al Ti₃the reinforcement phase improve the wear resistance of the cladding layer.Through the microhardness and wear resistance test of the cladding layer,it can be obtained that the microhardness of the cladding layer has a certain fluctuation between1207?1344HV,up to 1344HV,which is 3.5 times that of the TC4 titanium alloy matrix.The minimum wear loss of the cladding layer is 0.35mg,and the weight loss of the substrate is 65.08mg;the average friction factor of the TC4 titanium alloy substrate is about 0.65,and the minimum friction factor of the cladding layer is about 0.25;the wear resistance of the cladding layer is remarkable improve.Through the oxidation kinetics curve of the high temperature oxidation test of cyclic oxidation at 800?×100h,it can be seen that the oxidation weight per unit area of the TC4 titanium alloy matrix cyclically oxidized is 25.10mg·cm^-2,and the cladding layer is cyclically oxidized The oxidation weight gain of the area is 6.01 mg·cm^-2.According to the XRD pattern analysis,the oxide layer of the TC4 titanium alloy matrix mainly contains Ti O₂,Al₂O₃and a small amount of V₂O₅,and the surface of the titanium alloy matrix is seriously oxidized.The oxide layer of the cladding layer mainly contains Cr₂O₃,Ti O₂and Al₂O₃.The surface oxide layer of the cladding layer is intact,forming a densely structured oxide film,which prevents the entry of outside air and prevents further oxidation of the inside of the cladding layer.The high temperature oxidation resistance of the cladding layer has been significantly improved.