Structure and mechanical properties of TiAlSiN/Si3N4 multilayer coatings

TiAlSiN/Si3N4 multilayer coatings which have different separate layer thicknesses of TiAlSiN or Si3N4 were deposited onto glass sheets, single-crystal silicon wafers and polished WC–Co substrates by reactive magnetron co-sputtering. The morphology, crystalline structure and thickness of the as-prepared multilayer coatings were characterized by TEM, SEM, XRD and film thickness measuring instrument. The mechanical properties of the coatings were evaluated by a nanoindenter. The effects of monolayer thickness on the microstructure and properties of TiAlSiN/Si3N4 multilayer coatings were explored. The coatings showed the highest hardness when the thickness of Si3N4 and TiAlSiN monolayers was 0.33 nm and 5.8 nm, respectively. The oxidation characteristics of the coatings were studied at temperatures ranging from 700 °C to 900 °C for oxidation time up to 20 h in air. It was found that the coatings displayed good oxidation resistance.