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In the present study, PA6 polymers with and without solid lubricant inclusions were investigated against S1100QL steel surfaces that had different surface roughness values—a very high surface roughness (Rz ≈ 40 µm) and a low surface roughness (Rz ≈ 5 µm). Static and dynamic friction coefficients were analysed under a series of nominal contact pressures (2.5 to 40 N/mm2) considering the influences of polymer water saturation, temperature, counter-body surface roughness and lubrication. Mechanisms for the observed influences of the respective parameters are provided and are interpreted from the view of the adhesive and deformative contributions to the friction force. [ABSTRACT FROM AUTHOR]

The influence of temperature on friction and wear of unlubricated DIN 100Cr6 steel/steel contacts was studied in different anaerobic gaseous atmospheres, namely argon (Ar), nitrogen (N 2 ) and carbon dioxide (CO 2 ), and air atmosphere was used as benchmark. Tribological experiments were performed at high temperature (200 °C) and the results were compared with previously published results from experiments performed at ambient temperature (20 °C). Reciprocating ball-on-disc tribological tests were conducted with high contact pressures (maximum initial contact pressure of 1.5 GPa). In all anaerobic gas atmospheres at high temperature, lower friction and wear were measured than in air atmosphere. The lowest friction and wear were measured in CO 2 atmosphere; they were slightly higher in N 2 atmosphere and even more slightly higher in Ar atmosphere. In all anaerobic atmospheres, different oxidation kinetics of steel surfaces occurred as compared with air atmosphere. For N 2 and CO 2 atmospheres, XPS analyses of the wear debris showed an increased concentration of non-carbidic carbon and furthermore for the CO 2 atmosphere, iron–carbon–oxygen layers were also found which probably provided the very favourable friction and wear properties observed in this atmosphere. In N 2 and CO 2 atmospheres, higher wear and friction were observed at high temperature than at ambient temperature, which indicates that at high temperature, a deterioration of the beneficial properties of the N 2 and CO 2 -reacted tribolayers occurred. On the contrary, in Ar atmosphere at high temperature, a decreased adhesion and a significantly lower wear as compared with ambient temperature was observed. [ABSTRACT FROM AUTHOR]