Der Einfluss des E-Moduls und des Grundöls auf das Wälzverhalten von DLC- und Diamantbeschichtungen

Nano-cristalline diamond and DLC (ta-C, a-C:H) coatings on 100Cr6 steel and SSiC (Ekasic D) substrates were tested under lubricated slip rolling conditions. The tests were performed in an Amsler-type testing rig with unadditivated paraffin oil or glycol (PAG 46) under boundary/ mixed lubrication. The initial average specific pressure was adjusted between P m = 1,0 GPa, and P m = 2,0 GPa. Discs consisting of diamond coated SSiC, HIP-ZrO 2 or 100Cr6 steel served as counterparts. In all tests presented here, glycol led to lower friction coefficients, but larger damages, with respect to paraffin oil. Under paraffin oil lubrication, DLC-coatings on 100Cr6 substrates tested against 100Cr6 discs showed virtually no sign of damage after n = 1.000.000 cycles. In contrast, diamond coatings on SSiC tested against discs of the same material or 100Cr6 discs failed after about n = 10.000 cycles. Starting point for the failure of the diamond coatings are fractures in the SSiC substrates. Using HIP-ZrO 2 discs as counterparts, the lifetime of the diamond coatings could be extended by a factor of ten.