TRIBOLOGICAL CHARACTERIZATION OF HARD CARBON-FILMS PREPARED BY LASER-ARC EVAPORATION

Hard diamond-like carbon films were deposited onto silicon wafers and hardened steel substrates using laser-induced vacuum arc evaporation ( Laser-Arc). The deposition was carried out in a vacuum of approximatel y 10(-4) Pa with an arc repetition frequency of 100 Hz, a peak current of 500 A and a pulse duration of approximately 37 mus. After substrat e cleaning by Ar+ ion bombardment films were prepared at different dep osition temperatures up to a thickness of approximately 0.5 mum. The t ribological behavior of as-deposited carbon films was studied using a vibration wear technique with a steel ball (AISI 52100) as counterbody . To check the effect of the water content of the surrounding air, tes ts were performed in air at ambient temperature but of varying relativ e humidities. From in situ measurements of friction and wear, the trib ological lifetime of the films was determined. From a wear scan at the end of testing and additional profilograms, the wear of the ball and that of the disk were calculated separately. The results demonstrate t hat very good wear resistance and a low coefficient of friction is obt ained for specific conditions of the Laser-Arc coating process. Howeve r, the friction and wear of all coatings increased strongly in dry air . These results are the basis of further investigations to modify the coating process by Laser-Arc.