Study On Properties Of Modified Diamond-like Carbon Films Prepared On Surface Of 2024 Aluminum Alloys

As a kind of light alloy,aluminum alloys have the characteristics of low density,high specific strength,good workability and good corrosion resistance.Therefore,they have a wide range of applications in construction,transportation,ocean and other fields.However,aluminum alloys have low hardness and poor wear resistance,and are prone to pitting corrosion in a chloride ion environment,which affects the life and safety of aluminum alloys,thus the further application of aluminum alloys is limited in various fields.Surface modification is an effective method to improve metal surface properties.Plasma-enhanced chemical vapor deposition can not only realize the surface modification of aluminum alloys at low temperature,but also can prepare diamond-like carbon films with high hardness,high elastic modulus,excellent wear resistance and friction reduction performance and good chemical inertness on the surface of aluminum alloys.Therefore,in this article plasma enhanced chemical vapor deposition technology was used to prepare diamond-like carbon films on the surface of 2024 aluminum alloys.The morphology of diamond-like carbon films was observed by scanning electron microscope,atomic force microscope and super depth of field.The structure of diamond-like carbon films was characterized by Raman spectroscopy and infrared spectroscopy.The mechanical properties of the films were characterized by friction and wear tester,scratch tester and nanoindentation technology.The corrosion resistance of diamond-like carbon films was characterized by electrochemical workstation.In addition,the seawater erosion resistance of 2024 aluminum alloys and silicon-doped diamond-like carbon films were tested by a self-made simulated seawater erosion device.The influence mechanisms of pulse voltage,pulse width and silicon doping on the structure and performance of diamond-like carbon films were analyzed and discussed.The main progress made in the paper is as follows:The effect of pulsed voltage on the structure and properties of diamond-like carbon films was studied.The results showed that as the increase of pulse voltage,the formation of sp~2 hybrid structure was promoted in the films,the content of C-H bonds was reduced in the films,and the bonding strength between films and substrate was decreased gradually.When the pulse bias was 1800V,the hardness and elastic modulus of the film were the highest,the friction coefficient was the lowest,and corrosion resistance of the film was the best in the chloride ion solution.The effect of pulse width on the structure and properties of diamond-like carbon films was studied.The results showed that the pulse width had little effect on the formation of sp~3hybrid bonds in the films,but had a certain effect on the distortion of sp~2hybrid bonds in the films.When the pulse width was 15?s,the distortion of the sp~2hybrid structure in the films was larger.The internal stress in the films was slightly higher,the hardness and elastic modulus of films were higher,and the corrosion resistance of films was the best in the chloride ion solution.The influence of silicon doping on the structure and properties of diamond-like carbon films was studied.The results showed that as the addition of silicon,the formation of sp~3 hybrid bonds was promoted in the films,the content of C-H bonds was increased in the films,and the internal stress in the films was reduced.However,more nanopores was appeared in the films with content of 10%silicon.When the content silicon was 2%,the friction coefficient of films was the lowest,the hardness and elastic modulus of films were the highest,and the corrosion resistance of films was the best in the chloride ion solution.The erosion and corrosion behavior of 2024 aluminum alloys and silicon-containing diamond-like carbon films in simulated seawater was studied.The results show that the corrosion resistance of the films was improved due the formation of silicon oxide,and the silicon-containing diamond-like carbon films had a better protective effect on the 2024 aluminum alloys.