Development of ZrCN decorative coatings deposited by high-power impulse magnetron sputtering

HiPIMS has established itself as one of the most promising PVD techniques in recent years. A breadth variety of coating properties are achievable with this technique thanks to the large number of parameters that can be tuned. That means that the coating optical response and properties can be optimized by changing the right parameters. Zr-based coatings are finding more applications in the decorative field because of the outstanding mechanical properties and variety of colors they can offer. Given the strong sensitivity of color in HiPIMS ZrCN coatings, it was important to adopt a structured exploration strategy. The first step was a primary mapping of the parameter space. Acetylene flow and peak current were varied together, because these two parameters are expected to dominate plasma chemistry and discharge conditions. The goal at this stage was to identify dominant optical trends. Based on this analysis, a reference condition was selected and used as a baseline for all subsequent variations. Starting from this reference condition, ZrN and ZrC interlayers before the deposition of the ZrCN top-layer were tested. After the selection of a new baseline, substrate bias and temperature, were then varied one at a time. This sequential variation avoids confounding effects and allows changes in color to be attributed to a specific parameter with much higher confidence. This approach is essential in a highly coupled system like HiPIMS, where simultaneous parameter changes can easily lead to misleading interpretations. Eventually, exhaustive characterization techniques have been carried out with the aim of relating the coatings properties and behaviors.