Structure and properties of Al–Ti–Si–N coatings prepared by the cathodic arc ion plating method for high speed cutting applications

Al–Ti–Si–N coatings with several Al/Ti/Si ratios were deposited on WC–Co substrates by the cathodic arc ion plating method. Microstructure and compositions of the local parts of the films were investigated by using transmission electron microscopy with EDS. The films seemed to have the same columnar structure as (Al,Ti)N films but with a smaller column size. The crystal structure, hardness and oxidation resistance were investigated, and Al–Ti–Si–N films with cubic B1 crystal structures had higher hardness than (Al,Ti)N films. Similarly, the Al–Ti–Si–N films displayed greatly improved oxidation resistance at elevated temperatures of up to 1100°C in air. The cutting performances of (Al,Ti,Si)N coated carbide endmills were evaluated and offered significantly better performance in the machining of hardened steels with higher cutting speeds. The wear mechanism and cutting characteristics are discussed along with the film properties.