The effect of graphite surface texturing on the friction reduction in dry contact

Investigations were performed to study the effect of graphite surface texturing on the friction coefficient reduction of graphite-steel sliding pair in dry flat contact. Friction tests were carried out using an Optimol SRV 5 tester, equipped with a rotation pin-on-disc module. Graphite discs of 100 mm diameter and 10 mm thickness were tested. Surface texturing was made with abrasive jet machining. Counter samples made of 42CrMo4 steel were polished. Four types of textured surfaces were tested. The tests revealed that a direction of the converging bottom texture had a substantial effect on the scatter of the friction coefficient. High stability and low value of the coefficient of friction were achieved for the disc texture with bottom steps parallel to the arm of the chevron. Low friction forces were obtained for the angle between arms of 120 degrees.