Research On Wear Resistance And High Temperature Oxidation Resistance Of Laser Cladding Coating On Titanium Alloy TC4 Surface

In order to improve the high temperature oxidation resistance and wear resistance of titanium alloy TC4,Ni60A-50%Cr₃C₂was selected as the cladding powder to laser cladding on the surface of titanium alloy TC4.The effects of different Y₂O₃addition on the cladding layer were studied.The optimum cladding powder and ratio,as well as the optimum laser cladding process parameters were obtained.The phase and microstructure of the cladding layer were analyzed by XRD,EDS and SEM.Microstructure,microhardness,wear resistance and high temperature oxidation resistance of the cladding layer were tested,and its mechanism was analyzed.The following conclusions were obtained:（1）Adding different percentages（0.2%,0.5%,0.8%,1.0%,2.0%,3.0%）of Y₂O₃to the cladding layer in Ni60A-50%Cr₃C₂mixed powder,and obtaining Y2O3 as 1%,the cladding layer is grain refined,has no pores,and has the highest microhardness.（2）The optimum process parameters are:power of 600W,scanning speed of2mm/s,powder feeding rate of 0.8r/min,defocusing amount of 0,and lapping rate of30%.A cladding layer having no pores,cracks,and good metallurgical bonding can be obtained.（3）By SEM analysis,the cladding layer is composed of cell crystals,dendrites,and planar crystals.By EDS and XRD analysis,the cladding layer contains phases such asγ-Ni,Ti C,Cr₇C₃,Cr₂₃C₆,Cr₃Ni₂,Ni₃Ti,Al Ti₃,Cr₂Ti.Among them,Ti C,Cr₇C₃and Cr₂₃C₆act as reinforcing phases,increasing their hardness and wear resistance.The maximum microhardness of the 1%Y₂O₃cladding layer can be up to 1604 HV,which is about 4 times that of the matrix.（4）Through the friction and wear test:the wear of the cladding layer is much smaller than the wear of the substrate,and the Cr₇C₃,Cr₃C₂and Ti C reinforcing phases in the cladding layer material significantly improve the hardness and wear resistance.The titanium alloy matrix is mainly furrow and micro-cutting,which is abrasive wear.The surface of the cladding layer is a small scratch and does not have any defects,and is also abrasive wear.（5）It is obtained by high temperature oxidation test:It can be seen from the oxidation kinetic curve that the high temperature oxidation performance of the cladding layer is five times that of the titanium alloy matrix.XRD pattern analysis of the titanium alloy TC4 oxide layer can be obtained,and the oxide layer contains mainly Ti O₂and Al₂O₃.The XRD pattern analysis of the oxide layer of the cladding layer can be obtained.The oxide layer of the cladding layer mainly contains Ti O₂,Cr₂O₃,Al₂O₃and Si O₂.Through cyclic oxidation at 850°C×100 h,the titanium alloy matrix is severely oxidized and the oxide film is peeled off;the surface of the cladding layer is intact,forming a uniform and dense Cr₂O₃oxide film,which separates the oxygen and the cladding layer and prevents oxidation of the oxygen and cladding layers.The reaction and high temperature oxidation performance are significantly improved.