magnetic stirrer for 30 minutes the rotation of the ring prevented the sedimentation of particles in the reservoir during the test the friction coefficient values during each wear test were recorded automatically by a computer the block wear scar depth was measured by scanning the wear track in a stylus profilometer while the coating wear was estimated based on the visual inspection the block wear was used as the measure of counterface friendliness for any given coating it should be noted that all coatings yielded low coefficient of friction typically lt 0 1 as long the dlc remained intact during the cetr bor test this is a wet sand rubber wheel abrasion test designed to simulate a lower load and very severe abrasion environment the standard astm g105 test is run using rubber wheels of four different shore hardness however in order to avoid complexity the astm g105 test was modified for this study where the specimen was tested in contact against a rotating rubber wheel of given shore is hardness a 58 62 tests were run in a falex wear tester keeping the rubber wheel partially submerged in a mixture of sand and water the wheel was rotated at 200 rpm for 30 minutes.