Thermal stability and wetting properties of Cr-O-C coatings synthesized by plasma immersion ion processing

摘要

Microcrystalline Cr-O-C films, synthesized by the plasma immersion ion processing technique, were annealed in vacuum and air at 700 deg C for different times so their thermal stability could be evaluated. The study showed that annealing does not greatly change the chemical composition of the Cr-O-C films but induces a transformation of the film structure from the mixed phases of Cr_2O_3, CrO_2, and CrC_(1.13)O_(0.12) to the dual phases of Cr_3C_2, and Cr_2O_3. In addition, the annealed Cr-O-C films exhibit excellent nonwetting qualities to liquid aluminum despite the presence of pin holes. The contact angle of resolidified molten aluminum against the Cr-O-C films was found to be as high as 120-150 deg. The aluminum contact angle was found not to vary with thermal aging of the Cr-O-C films. The Cr-O-C films showed high hardness (16-24 GPa) and good wear resistance as compared to the steel substrates (H13 and 304 stainless steels) used in this study.