Design verschleißreduzierender amorpher Kohlenstoffschichtsysteme für trockene tribologische Gleitkontakte

Description

The hydrogenated amorphous carbon coatings (a-C:H) have huge potential for tribological applications under lubricated as well as dry contact conditions. The a-C:H thin coatings are well known for their unique chemical structure, which is composed of diamond-like and graphite-like carbon bonds. Therefore, the coatings have high hardness with lubrication effect. The aim of this present work is to modify the design of a reference a-C:H coating system on tool steel, in order to increase the wear resistance under dry sliding conditions. The background for the present investigations is to realize a lubricant-free sheet metal forming process by tool-sided surface modification. The modified factors in regard to coating design were the adhesive layer, the coating thickness and deposition gas atmosphere. The main emphasis was on their influences on the tribological characteristics compared to the reference a-C:H coating system. The wear resistance of the modified coating systems was analyzed by a modified scratch tester in sliding contact with regard to the load force and number of cycles. After the tribological evaluations, the wear traces were studied using scanning electron microscope and the wear mechanisms of the coating systems were identified. Finally, the influences of all the above-mentioned factors on the wear resistance under lubricant-free conditions were identified, and a process window was derived from the results.