Structural, mechanical and thermal properties of Ti1-xSixN/CrAlN (x = 0, 0.13 and 0.22) multilayers

Nanoscaled Ti1-xSixN/CrAlN multilayers combining the cutting edges of Ti1-xSixN and CrAlN coatings are currently the focus of attention of researchers. Here, the structural, mechanical, and thermal properties of Ti1-xSixN/CrAlN multilayers with varied Si content were investigated. The hardness values of Ti1-xSixN/CrAlN multilayers are individually enhanced to 30.7 ± 1.0 GPa for x = 0, 36.0 ± 1.3 GPa for x = 0.13, and 35.9 ± 1.5 GPa for x = 0.22 from the 27.4 ± 0.3 GPa for CrAlN due to interfacial strengthening effect. Ti1-xSixN insertion layers retard the thermal decomposition process of CrAlN. After annealing at 1200 °C, the hardness of Ti1-xSixN/CrAlN (x = 0, 0.13, 0.22) multilayers is individually enhanced by ∼6.9, 12.9 and 13.6 GPa from the 18.7 ± 1.1 GPa for Cr0.32Al0.68N. However, Ti1-xSixN insertion layers lead to a drop in the oxidation resistance of CrAlN coatings due to their inferior oxidation resistance. Noticeable is that increasing Si content of Ti1-xSixN/CrAlN multilayers causes a decline in the thickness of oxide scales.