Properties of (Ti,Al,Si)N coatings for high demanding metal cutting applications deposited by HPPMS in an industrial coating unit

Abstract

Abstract Hard and smooth coatings with high oxidation resistance and thermal stability are used for economical machining. In this regard, nc‐(Ti,Al)N/a‐Si 3 N 4 films were sputtered on tungsten carbide cutting inserts and WC/Co samples by using an industrial CC800/9 high power pulse magnetron sputtering (HPPMS) coating unit. Coating composition and mechanical properties were investigated by scanning electron microscopy (EDS) and nano‐indentation. Hardness was about 36 GPa for a silicon content of about 9.6 at%. Optical emission spectroscopy (OES) was done to detect the ionization fraction of deposition species and to compare it to direct current (dc). Deposition rate of the HPPMS coatings was 1.6 times higher on areas positioned orthogonal to the target compared to dc sputtered coatings. Finally cutting performance was compared to a state‐of‐the‐art coating in turning HSS (high speed steel) under severe conditions. After the cutting tests SEM pictures were taken at the flank side of the cutting inserts to detect the wear. Cutting results show enhanced cutting performance due to the application of the HPPMS‐technology resulting in denser structure, higher hardness, smoother surface and better thickness uniformity compared to dc.