Microstructural transformation and failure mechanism of CrN/CrTiSiN coatings experienced annealing post-treatment

Abstract

There are great efforts for enhancing the characteristics of PVD multilayered coatings and one solution could be heat treating the coated part. The current research analyzed the effect of annealing temperatures on the microstructural transformation and failure mechanism of CrN/CrTiSiN multilayered coatings. The coatings were annealed in air at temperatures ranging from 500 °C to 1000 °C for 1 h. The characterization methods included XRD, XPS, FESEM, EDS, and Rockwell-C adhesion tests. The findings indicated that the as-deposited coating exhibited a consistent structure of the CrN phase. During the process of annealing from 500 to 700 °C, the CrN phase transforms into the Cr2N phase. At 800 °C, the structure is fully composed of Cr2N. At 900 °C, the elevated annealing temperature causes the Cr2N phase to change into the Cr2O3 phase. The volume fraction of the Cr2O3 phase increases until the temperature reaches 1000 °C. The results showed that the transition of Cr2N → Cr2O3 within the coating's thickness would lead to peeling off the coating due to an increase in the lattice volume. The EDS mapping shows that raising the annealing temperature for a constant time will result in more oxygen infiltration into the coating's thickness.