Plasma based ion implantation technology for high-temperature oxidation-resistant surface coatings

Ir–Re alloy surface coatings were performed by means of plasma based ion implantation (PBII) technology, using a coaxial type arc-vacuum metal-plasma source, in order to prevent surface oxidation of the engineering tools (WC alloys) at high temperature. The energy controllability of the PBII process allows implantation of high-energy ions, to improve adhesion properties, and subsequent deposition at low temperature for producing very pure metal and alloys. The properties of the Ir–Re alloy produced with the PBII technology (PBII-film) were studied in comparison with films prepared by a conventional sputtering method (SP-films), which needs a Cr interlayer for assuring good adhesion. Both types of coatings were heat treated at 570 °C for approximately 170 h, in nitrogen atmosphere, and analyzed by Scanning Electron Microscopy, Auger Electron Microscopy and cross sectional Transmission Electron Microscopy. The results showed that the heat treatment did not alter the surface of the PBII-films. On the contrary, the SP-film surface became very rough after heat treatment. Because the Cr diffused from interlayer to the surface and oxidized. Therefore, PBII-films were also more resistant to scratch tests.