Duplex coating technique to improve the adhesion and tribological properties of CrAlSiN nanocomposite coating

- Nanocomposite CrAlSiN film can be successfully coated on nitridation AISI 304.
- The adhesion of coatings increased with process time and working power.
- The coating on substrate with 19.7 at.% nitrogen has almost zero wear rate.
- XRD suggested that nitriding process reduced structure incoherence.

The study is intended to solve the adhesion problem of high residual stress nanocomposite CrAlSiN coating deposited on the AISI 304 substrate. The duplex coating system via low pressure plasma nitriding and RF magnetron sputtering is used. Nitriding experiments are carried out at low temperature 500 °C for 1 h, 2 h, and 5 h with RF power 150 W, 225 W, and 300 W. It is revealed that the substrate with 19.7 at.% nitrogen exhibits the outstanding adhesive strength. The specimen is characterized by X-ray diffraction, atomic force microscopy, and transmission electron microscopy. The strengthening mechanisms in adherence are addressed and can be related to the crystal structure, thermal expansion coefficient, surface roughness, and diffusion layer between the coating and the substrate. Tribological properties of the coatings on the substrate with various nitrogen contents are investigated. The coating on the substrate with 19.7 at.% nitrogen shows the best wear resistance which has almost zero wear volume.