Study On Properties Of Diamond-like Carbon And Si/F Diamond-like Carbon Films Prepared On AZ31 Magnesium Alloy

Nowadays,magnesium alloys have been widely used in various industries.However,the disadvantages of low hardness,poor wear resistance and poor corrosion resistance limit the development of magnesium alloys.Surface coating is one of the high-profile issues which can effectively improve the surface hardness,abrasion resistance and corrosion resistance of the magnesium alloy without changing the inherent properties of magnesium alloy.Chemical vapor deposition technology is an effective method to achieve low-temperature coating on the surface of the substrate.Diamond-like carbon films have high hardness,wear-resistant and other properties,and have good chemical inertness and biocompatibility.A diamond-like carbon film was prepared on the surface of AZ31 magnesium alloy by plasma enhanced chemical vapor deposition in this study.The surface morphology of the film was observed with an atomic force microscope;the microstructure and composition of the film were characterized using Raman spectroscopy and infrared spectroscopy;the mechanical properties of the film were measured using a friction and wear tester,a scratch tester and a nanoindenter and mechanical properties were measured;the corrosion resistance of the film was tested using an electrochemical workstation.The effects of deposition temperature,doping elements and deposition atmosphere on the surface morphology,microstructure and mechanical properties of diamond-like carbon films were also analyzed and discussed.The main progress of the paper is as follows:The effects of deposition temperature on the microstructure and mechanical properties of diamond-like carbon films were studied.It was found that the thickness and roughness of the films changed with the change of deposition temperature.When the deposition temperature is 75°C,the thickness of the film is the largest,about 7.67?m,and the roughness is the smallest.The density and flatness of the film are the highest.When the deposition temperature is 75°C,the modulus and hardness of the diamond-like carbon film are the largest,reaching 43.2GPa and 5.95 GPa,respectively,and the friction coefficient is the lowest,being only 0.03.As the deposition temperature keeps increasing,the sp3 bond content in the film increases first and then decreases.When the deposition temperature is 75°C,the contain of sp3 bonds in the film is the most,and the mechanical properties of the film are excellent.The effects of silicon content on the structure and mechanical properties of diamond-like carbon films prepared on the surface of AZ31 magnesium alloy were studied.It was found that with the increase of silicon content in the film,the ID/IG ratio gradually decreased,and the amount of sp3 in the film was increased.Thesurface roughness of diamond-like carbon films was gradually increased.Compared with diamond-like carbon films,the hardness and modulus of silicon-doped diamond-like carbon films have decreased,but with the increase of silicon content in films,the hardness and modulus of films have increased.The corrosion behavior of fluorinated diamond-like carbon films prepared on the surface of AZ31 magnesium alloy in simulated human body fluids was studied.It was found that as the increases of carbon tetrafluoride deposition time,the roughness of the diamond-like carbon film decreases.The sp2 hybrid bond in the film gradually increases.The hydrophobicity of the diamond-like carbon film increases first and then decreases when carbon tetrafluoride is deposited.When the deposition time is 40 minutes,the film exhibits excellent resistance to human body fluid corrosion.The effect of deposition atmosphere on the diamond-like carbon film prepared on the surface of AZ31 magnesium alloy was studied.It was found that as the acetylene gas flux increased,the hardness and modulus of the film decreased.At the same time,the ID/IG ratio increased by Raman spectroscopy,the sp3 bond content decreased,and the film tended to have a graphite structure.