Structural and mechanical properties of multilayered gradient CrN/ZrN coatings

Multilayered gradient CrN/ZrN coatings were synthesized by a dual cathode dc magnetron sputtering. The influence of species of reaction gases and partial pressures on structural and mechanical properties was explored. Both nanoindentation and nanoscratch fracture tests showed that multilayered gradient coatings possessed much higher hardness and fracture resistance than monolithic ZrN and CrN coatings. A proper percent of NH3 in N2 reaction gas was proved to be of benefit to the synthesis of high hardness and fracture-resistant CrN/ZrN coatings with strong adhesion to substrate. The hardness and critical fracture load exceed 55 GPa and 100 mN, respectively. The multilayered gradient structure with strongly mixed CrN(111), Cr2N(112), ZrN(111), and ZrN(220) orientations is responsible for the enhanced mechanical properties.