Preparation And Properties Of CrN Based Nanocomposite Coatings

CrN coating with high hardness,low friction coefficient and strong adhesion characteristics,was used as a surface protective material widely used in various artifacts,which can effectively improve the work efficiency and prolong the service life.With the progress of science and technology,the traditional binary coating was difficult to meet the requirements of modern processing.The preparation of multi-component coating to further improve its hardness and toughness,enhance the high temperature oxidation resistance and corrosion resistance,will greatly expand the application range of CrN based coating.This paper focuses on the preparation of CrAlSiN nanocomposite coatings by Plasma Enhanced Magnetron Sputtering（PEMS）.CrAlSiN coatings with different Si contents were prepared by changing the sputtering power of Si target on the basis of single variable principle and keeping other process parameters unchanged.The results showed that the addition of Si elements effectively inhibited the growth of columnar crystals,the grains were refined,and the coating surface was deformed from a hexagonal pyramid to an irregular island.With the increase of Si content,the microhardness,young’s modulus,elastic strain coefficient（H/E*）and plastic deformation resistance（H³/E*²）of the coating increased first and then decreased,the average friction coefficient and wear coefficient decreased first and then increased.When Si content was 16.37%,the coating’s mechanical properties and tribological properties were the best.The Si content has a significant effect on the high temperature oxidation resistance of the coating,and loose structure was the reason for the premature failure of the coating with low Si content.When Si content was 20.73%,the coating has the best anti-high temperature oxidation performance.The electrochemical corrosion results show that the corrosion resistance of coating decreases with the increase of Si content,and the increase of defect density was the main cause of corrosion failure of coating.CrAlSiN coatings with different Al content were prepared by controlling the sputtering power of Al target.The results show that Cr in the crystal partially replaced by Al forms the Cr（Al）N solid solution,and the coating surface was irregular.With the increase of Al content,the adhesion of the coating gradually increased.Hardness,young’s modulus,H/E*,H³/E*²,average friction coefficient and wear rate all showed a trend of decreasing first and then increasing.When Al content was 27.72%,the coating’s mechanical properties and tribological properties were the best.The coating’s high temperature oxidation resistance first strengthened and then weakened with the increase of Al content,the increase of surface defects and thermal expansion mismatch stress were the reasons for the coating’s oxidation failure.When Al content was 27.72%,the coating’s high temperature oxidation resistance was the best.The electrochemical corrosion results showed that the failure mechanism of the coating was grain boundary corrosion.With the increase of Al content,the corrosion current(I_corr)first decreased and then increased.When Al content was 27.72%,the corrosion resistance of the coating was the best.