Microstructure And Mechanical Properties Of CrAlN Coatings Deposited By Magnetic Enhanced Multi-arc Ion Plating Technique

Al Cr N coatings show excellent abrasive resistance, high temperature oxidation resistance and high hardness, and have been successfully used for materials protecttion and particularly to improve cutting tools life. Cr N/Al Cr N nano-multilayer coatings present the advantages of Cr N and Al Cr N coatings to some extent. The effect of nano-scale and modulation structure of Cr N/Al Cr N nano-multilayer coatings have important significance on the properties in theoretical and engineering applications.Cr Al N hard coatings were deposited onto M2 high speed steel and 304 stainless steel specimens by magnetic enhanced multi-arc ion plating technique. Plasma discharges were studied in argon atmosphere and nitrogen atmosphere separately with different magnetic intensity, nitrogen pressure, rotation rate, substrate bias, Al Cr target current and Cr target current. The morphology and crystalline structure of the as-deposited coatings was analyzed and the effect of technological parameter on adhesive strength, abrasive resistance, hardness and corrosion resistance of the coatings were also studied.The technological parameter has a great influence on plasma discharges and the substrate current increased greatly when the coil current, substrate bias and target current increased, but the substrate current decreased when gas pressure increased.The magnetic enhancement device could change the morphology and the movement of the cathode spots. The large particles of the coating face decreased obviously compared with the coatings without magnetic enhancement and the enhanced magnetic also improve the gas ionization.The as-deposited Cr Al N coatings were crystallized into a rocksalt-type cubic structure, and the coatings exhibit(111) and(311) preferred orientation. Increase of the coil current, gas pressure and substrate bias could improve the compactness of the coatings, and the number of the large particles decreased when substrate bias improved.Al content would changed with the change of the Al Cr target current and Cr target current and the increase of Al content could cause lattice distortion and results in a finer structure or a decrease of the crystallinity. The rotation rate has a great influence on the stress of the coatings.The Cr Al N coatings exhibit compact texture, adhesive strength of 70 N, hardness of about 21 GPa, excellent abrasive resistance and better corrosion resistance with coil current of 0.6A, rotation rate of 1.5r/min, substrate bias of-100 V and nitrogen pressure of 1.2 Pa.