Effects of linearly ramping substrate bias on microstructure and cutting performance of TiAlN coating

Abstract

The aim of this study was to verify the effects of linearly ramping substrate bias on microstructure and cutting performance of TiAlN coating. TiAlN film was deposited by linearly ramping substrate bias voltage from -50 V up to -150 V on a WC-Co substrate using the cathodic arc ion plating method. The film microstructure was evaluated by electron backscatter diffraction pattern (EBSP) analysis. EBSP observation showed that the column size decreased from about 500 nm at the substrate/film interface to less than 200 nm at the surface of the film. Especially, the microstructure changed markedly at the middle of the film (about -100 V). The milling performance of coated inserts was examined with AISI 1049 steel as a work material. In particular, the cutting inserts deposited at the linearly ramping substrate bias voltage showed enhancement of tool life and chipping resistance of the cutting edge by approximately twofold compared to when the substrate bias was kept constant in this test.