Study On The Properties Of Magnetron Sputtering TiCN Film And Its Composite Film On AZ31Magnesium Alloy

Magnesium and its alloys have been paid attention to and widely used inautomotive industry, microelectronics, aerospace industry and many other fields,because of their large reserves and excellent properties in recent years. However, poorcorrosion resistance of magnesium and its alloy that seriously limits their applications.To improve their corrosion resistance is the most important issue of the current Mgalloys research and development. Nowadays, people mainly improve the alloy technicsand modify the surface property of Mg alloy to improve the corrosion resistance.Among many available technologies, magnetron sputtering was deemed to be one of thebest methods to prepare the exterior coating because of the high film quality, simpletechnics and environment-friendly feature.In this study, Titanium Carbonitride (TiCN) films, SiTiCN films, Si/SiTiCN,SiN/SiTiCN composite membrane were deposited by radio frequency magnetronsputtering on AZ31Mg alloys.Field emission scanning electron microscope, X-raydiffraction, X-ray photoelectron spectroscopy instrument and profilometer were appliedto investigate the surface morphology, microstructure, chemical composition and thethickness of the film, respectively.The corrosion resistance of the film was studied byelectrochemical test, and the influence of the preparation parameters to the quality ofTiCN films and SiTiCN films was researched.The research results show that the films prepared by RF magnetron sputtering areuniform and compact, and exhibit amorphous structure.When the sputtering power of TiCN compoundtarget is60W, the total pressure is1.0Pa, the N2flow rate is8sccm and the sputtering time is4h, the prepared TiCN filmhas the best corrosion resistance in3.5wt.%NaCl solution. Furthermore, the corrosioncurrent density of TiCN film coated AZ31Mg alloy (3.84×10-7A/cm2) was reduced bynearly two orders of magnitude compare to the Mg alloy substrate (2.28×10-5A/cm2).XPS characterization showed the prepared TiCN films containing Ti, N, C, Oelements, O mainly come from the air caused by adsorption and oxidation. On the otherhand, when the sputtering power of Si target is60W and the sputtering time is6h, theprepared SiTiCN film has the best corrosion resistance, the corrosion current density ofSiTiCN film coated Mg alloy (3.40×10-7A/cm2) was reduced by nearly two orders ofmagnitude compare to the substrate (2.28×10-5A/cm2). Through the narrow spectrum analysis, the main chemical bond of SiTiCN film contain Ti-C-N, Ti-N, Ti-C, Ti-O,Si-N, Si-C, Si–O, C-C and so on. Finally, the electrochemical detection of Si/SiTiCN,SiN/SiTiCN composite films showed that SiN/SiTiCN composite film can protect theAZ31Mg alloys better than Si/SiTiCN composite film.