Study On The Addition Of Ti₃SiC₂ Of Ni-based Composite Coatings On TC4 Alloy By Laser Cladding

Titanium alloy has high specific strength,excellent high temperature and corrosion resistance,low modulus of elasticity,good biocompatibility and other excellent properties.It is widely used in petrochemical,biomedical,aerospace and other fields.However,the low hardness and poor tribological properties of titanium alloy limit its application in high temperature moving parts.As a common and efficient surface modification technology,laser cladding could form self-lubricating high temperature wear-resistant coating on the surface of titanium alloy.which improving its friction and wear performance.Ti3SiC2,as a typical ternary layered Max phase ceramic solid lubricating material,has been widely studied by scholars due to its unique structure and excellent performance.However,there are few researches on the high temperature self-lubricating tribology of laser cladding Ti3SiC2 at present,and the mechanism of friction and wear at high and medium low temperature has not been systematically analyzed.In this paper,the self-lubricating and wear-resistant composite coatings were successfully prepared on TC4 alloy surface by laser cladding,which were used by the mixture powder of Ni60+5%Ti3SiC2(N1 coating),Ni60+10%Ti3SiC2(N2 coating)and Ni60+15%Ti3SiC2(N3 coating).The microstructure and phase of the composite coating were analyzed by means of XRD,SEM and EDS.the microhardness of the substrate and the coating was measured by microhardness tester.The tribological properties of the substrate and composite coatings were measured by ball disk high temperature wear tester and probe type surface wear tester at room temperature,300℃and 600℃,respectively.The mechanism of friction and wear was analyzed in detail.The results show that the microstructure of N1,N2 and N3 composite coatings are similar The main phases are y-Ni solid solution,intermetallic compound TixNiy,hard phase TiC/TiB and lubricating phase Ti3SiC2.The three composite coatings have good metallurgical bonding with TC4 alloy matrix,and the cross section of the coating has no obvious cracks and pores.The average microhardness of N1,N2 and N3 composite coatings are 1101.17 HV0.5、1037.23 HV0.5 and 907.41 HV0.5,respectively.Due to the presence of hard phases TiB and TiC in the laser cladding process,the microhardness of the three coatings are significantly higher than that of TC4 alloy(350 HV0.5).From room temperature to 600℃,the average friction coefficients of TC4 alloy are 0.51,0.49 and 0.47,the average wear rates of TC4 alloy are 35.96×10-5、25.99×10-5 and 15.18×10-5 mm3/(Nm);the average friction coefficients of N1 composite coating are 0.39,0.35 and 0.30,the average wear rates of N1 composite coating are 1.45×10-5、0.96×10-5 and 0.62×10-5 mm3/(Nm),respectively;The average friction coefficients of N2 composite coating are 0.41,0.45 and 0.44,the average wear rates of N2 composite coating are 1.45×10-5、0.96×10-5 and 0.62×10-5 mm3/(Nm);the average friction coefficients of N3 composite coating are 0.42,0.46 and 0.40,the average wear rates of N3 composite coating are 1.26×10-5、0.84×10-5 and 0.62×10-5 mm3/(Nm),respectively.It can be seen that the average friction coefficient and average wear rate of N1,N2 and N3 composite coating at different temperatures are lower than that of TC4 alloy,At 600℃,N1 composite coating has the smallest friction coefficient(0.30),and its main wear mechanism is plastic deformation,oxidation wear and oxide film delamination.At 600℃,N3 composite coating has the lowest average wear rate(0.62×10-5 mm3/(Nm)),and its main wear mechanism is hard particle peeling,three body wear and oxidation wear.