Mechanical, Structural and Thermal Properties of Multilayered Gradient Nanocomposite Coatings

Multilayered, gradient TiAlSiN-based nanocomposite coatings have been developed and investigated with respect to their applicability in the machining industry. The main coating layer was composed of 5-8 nm TiN and AlN nanograins. The coating possessed hardness as high as 40 GPA, which allows it to be classified as superhard. During heating up to 900 degrees C in air in steps of 100 degrees C for 6 h at each temperature, the coating showed good stability up to 700 degrees C. Thermal treatment over this temperature caused a decrease in the hardness to values characteristic for TiAlN multilayered coatings, while the adhesion to the substrate remained steady.