Iridium-based noble metal films, which show a relatively high oxidation resistance and high melting temperature, have been widely investigated as glass mold coatings due to its excellent reliability and performance in long-term high temperature usage. Recently, there has been an increasing interest in improving oxidation resistance and mechanical properties by the application for diffusion barrier layer and change of the alloy element content.
In this work, we investigated the thermal stability and mechanical properties of the Ir-based films prepared by ion beam assisted magnetron sputtering method. The microstructures and surface morphology were analyzed by X-ray diffraction and Scanning Electron Microscopy. Auger depth profiling is used to examine chemical composition variation with the samples annealed at high temperatures. Ball on disc type wear test was used to examine wear amount with respect to alloy element contents. The micro hardness test has been also utilized to take the mechanical properties of the samples.
In summary, two different sets of Ir based films(Ir-Re/Cr/Sub., Ir-Re/CrN/Cr/Sub.) were successfully deposited by ion beam assisted magnetron sputtering method. The Ir-Re/CrN/Cr sample showed more oxidation resistance than the Ir-Re/Cr sample, but higher than 500℃, both Ir-Re/Cr and Ir-Re/CrN/Cr samples were formed oxide phase, such as chromium oxide. Hardness values of the two different sets of Ir based films were decreased with increasing annealing temperature, while the values of the Ir-Re/CrN/Cr films were higher than these of Ir-Re/Cr films under high temperature conditions. Moreover, wear resistance are much improved with application for CrN barrier layer.
The mechanical properties of the Ir-based films by the change of the alloy element content show that the hardness value is decreased with Re contents under high temperature conditions. This must have been due to increasing structural defects by the volatilization of Re2O7. But wear resistance improved with increasing Re content at room temperature.