Abstract
Al-Cr-N films were deposited by a DC reactive sputtering method using three targets of 75at%Al25at%Cr, 50at%Al50at%Cr and 25at%Al75at%Cr disks. The Al-Cr-N films were characterized with respect to the chemical composition, crystal structure by XRD, GDS, TG-DTA, FE-SEM and TEM. The high temperature oxidation behavior of the films was investigated by heating at 1000ºC in air. The results were summarized as follows :
(1) The Al-Cr-N films were not severely oxidized at temperatures under 1200ºC. The oxidation resistance of the Al-Cr-N films was improved by more than 200 degrees compared with that of the Ti-Al-N film.
(2) Al0.75Cr0.25N film formed crystallized Al2O3 on the surface after heating at 1000ºC for 120min in air. Al0.5Cr0.5N and Al0.25Cr0.75N films formed two-phase mixtures of crystallized Al2O3 and Cr2O3.
(3) The protective layer composed of Al and Cr oxides was formed on the top surface of Al-Cr-N films during the high-temperature oxidation test. The oxidation resistance of Al0.25Cr0.75N film is the lowest among the Al-Cr-N films.
(4) The fractured cross section of Al0.5Cr0.5N film showed columnar structure before oxidation, and changed to granular structure after heating test at 1000ºC.
