Microstructure And Properties Of TC4 Alloy Laser Cladding Wear-resistant Self-lubricating Coating

Titanium alloy has low elastic modulus,high specific strength,excellent corrosion resistance and heat resistance Which was widely used in the fields of aerospace,petroleum,automobile,chemical industry and so forth.However titanium alloys's larger friction coefficient and poor wear resistance were limited its application range.Ni based alloy and ceramic powder were used as the coating materials to prepare composite wear resistant coating.Currently,Ni based alloy is the most widely used matrix materials due to its high temperature performance,high bearing capacity and wear resistance.Ni based wear resistant composite coatings were prepared by using the mixture of Ni based alloy and ceramic powder as cladding materials.Whereas with the continuous development of modern industry,not only need to improve the wear resistance of the coating,but also requires the coating with self-lubrication to satisfy where are difficult to use lubricating oil.Therefor,solid lubricant is usually added to the laser coatings such as h-BN,WS2,CaF2 and so on into Ni base alloy to obtain the wear resistant and anti friction coatings.In this paper,h-BN and Ti3 Si C2 are used as lubricant to prepare Ni based self-lubricating anti friction and wear resistant coatings.The microstructure and phase composition of the coatings were observed by XRD,SEM and EDS.The hardness,wear resistance and corrosion resistance of the coating were tested by micro-hardness tester,friction-abrasion testing machine and electrochemical workstation,what's more the strengthening mechanism and lubrication mechanism of the cladding materials were explained.Ni60+h-BN coating's phase are were mainly composed of TiC,TiB,TiB2,CrB,Ni3B,Ni2B and less h-BN.From the test results could be known that the content of h-BN is 10%,P=3 kW,V=8 mm/s get the maximum hardness value is about 1200 HV0.5,and obtained the minimum friction coefficient in 0.37?0.4,lower than the Ni60 coating about 36%.The corrosion potentials of Ni60+10%h-BN coatings all move positively with the increase of scanning speed,and the best corrosion resistance was obtained at V=10 mm/s.Ni60+Ti3SiC2 coating's phase are mainly composed of TiC,TiB2,Ti3SiC2,Ti5Si3,?-Ni solid solution,(Ti,V)C metal compound.When theTi3SiCz content is 7.5%,P=3 kW,=10 mm/s,obtained the maximum microhardness of the cladding layer is about 1150?1300 HV0.2;when the Ti3SiC2 content is 10%,P=3kW?V=12mm/s obtained the minimum friction coefficient is about 0.2?0.24,lower than the Ni60 coatings by nearly 40%,and the minimum wear mass of 1.1 mg is 50%lower than Ni60 coatings.With the increase content of Ti3SiC2,The corrosion resistance of Ni60+Ti3SiC2 coatings increases firstly,and then decreases.The best corrosion resistance is obtained when the content is 7.5%.