Study On The Properties Of Magnetron Sputtering Titanium Aluminum Nitride Film On AZ31Magnesium Alloy

Magnesium and its alloys have been paid attention to and widely used in manyfields such as automotive industry, microelectronics, aerospace industry and otherfields,because of their large reserves and excellent properties in recent years. However,poor corrosion resistance of magnesium and its alloy that seriously limits theirapplications. To improve their corrosion resistance is the most important issue of thecurrent magnesium alloys research and development. At present,people mainly adoptall kinds of surface coating technology. Among many available technologies, magnetronsputtering was deemed to be one of the best methods to prepare the exterior coatingbecause of the high film quality, simple technics and environment-friendly feature.In this study, Titanium Aluminum Nitride （TiAlN） films, Al-TiAlN, Ti-TiAlN,Zr-TiAlN composite membrane were deposited by radio frequency magnetronsputtering on AZ31magnesium alloy. Electrochemical system were performed toinvestigate and analyze corrosion resistance of the thin films, and study the influence ofprocess parameters on corrosion performance of TiAlN films on AZ31magnesium alloy.Focused ion beam scanning electron microscope, X-ray diffraction, X-ray photoelectronspectroscopy instrument, microhardness tester and profilometer were applied toinvestigate the surface morphology, microstructure, chemical composition, surfacehardness, film thickness and surface roughness of the film, respectively. The adhesionbetween film and substrate was evaluated by cross cut tape test.The research results show that the films prepared by RF magnetron sputtering areamorphous structure, and the adhesions of coating to the substrate are good. when the Altarget sputtering power is50W, the Ti target sputtering power is125W, the N2flow rateis30sccm and the sputtering time is8h, The prepared TiAlN film has the best corrosionresistance. Furthermore, the corrosion resistance of the AZ31mangesium alloy with theTiAlN coating was also effectively enhanced in the matter of fact that compared withthe uncoated magnesium alloy (1.066×10^-5A/cm²), the corrosion currentdensity(2.820×10^-7A/cm²) decreasd by more than one order of magnitude. XPScharacterization showed the prepared thin films containing Al, Ti, N, C, O five elements,C and O mainly come from the air caused by adsorption and oxidation. Through thenarrow spectrum analysis, each element film mainly TiN, TiO₂, TiON, AlN and Al2O3phase present. Microhardness tester and profilometer study showed that the titanium aluminum nitride thin film can effectively improve the magnesium alloy substratehardness, reduce the magnesium alloy substrate roughness.The electrochemical detection and soaking experiments of Al-TiAlN, Ti-TiAlN,Zr-TiAlN composite films showed Zr-TiAlN composite film can protect the AZ31magnesium alloys best, and Al-TiAlN composite film get the worst corrosion resistance.The cross cut tape test indicated that the adhesive strength between Zr-TiAlN, Ti-TiAlNcomposite film and magnesium alloy have reached one degree and the Al-TiAlNcomposite film has reached two degrees.