Study On Microstructure And Properties Of Anti-oxidation Coating Modified On Titanium Surface

Titanium and titanium alloys are widely used in modern industrial development in China.Titanium alloys have many advantages,such as light weight,high strength,good corrosion resistance and low production costs.Therefore,they are widely used in military and heavy industries,Biomedical and other important fields.However,the application limitation of titanium and its alloys is that the oxidation resistance of titanium alloys will be affected at high temperatures.Especially when the temperature is higher than 600?,oxidation problems are prone to occur,leading to a reduction in strength and toughness,which affects its application range at high temperatures.So,how to improve the high-temperature oxidation resistance of titanium alloys is an urgent problem for titanium alloys.Therefore,the surface of titanium and titanium alloys is coated with a composite coating with excellent high-temperature oxidation resistance.The intermetallic compound formed by the metallurgical reaction of the coating itself in a high-temperature environment can prolong the service life of titanium and titanium alloys and make titanium alloys inherent Performance continues.In this paper,three composite coatings of NiAl/Al,Ni Cu/Al,and NiCr/Al were prepared on the surface of pure titanium?TA1?by plasma spraying and arc spraying.High temperature oxidation tests of these three composite coatings at different times and temperatures in a high temperature heating furnace.Scanning electron microscope?SEM?,X-ray diffraction?XRD?and other instruments and equipment were used to analyze the sprayed and oxidized coatings and analyze the oxidation performance of the oxidized coatings and pure titanium to draw the oxidation kinetics curve.The anti-oxidation behavior of the three composite coatings under different oxidation temperatures and oxidation times was studied.The results show that NiAl/Al,NiCu/Al,and NiCr/Al composite coatings can easily react with oxygen to form a continuous and dense Al₂O₃ film during high temperature oxidation at 700?and 800?,which can effectively prevent Substrate oxidation rate.The Al coating melts,and the Al element diffuses into the Ni Al,NiCu and NiCr coatings,and forms an aluminum-rich phase diffusion layer mainly composed of NiAl,Ni2Al3,and NiAl3phases with the Ni element,hindering the penetration of oxygen.Al element also forms metallurgical compounds and solid solutions with Cu and Cr elements in NiCu and NiCr coatings,which helps to improve the oxidation resistance of the overall coating.In addition,during the preparation of the NiAl,NiCu,and NiCr coatings,Al in the NiAl welding wire,Cu in the Ni Cu powder,and Cr in the NiCr powder were sequentially oxidized to Al₂O₃,CuO,and Cr₂O₃,forming multiple strip or spherical barrier layers in the coating to prevent high temperature oxidation of the substrate.According to the analysis of the oxidation weight gain curve and the cross-section oxygen element surface scanning analysis,the oxidation resistance of the three composite coatings of NiAl/Al,NiCu/Al,and Ni Cr/Al was significantly improved compared with the unsprayed TA1.