EFFECTS OF ANTIWEAR ADDITIVES ON THE FRICTION AND WEAR OF SI3N4 STEELSLIDING CONTACTS/

Si3N4-based ceramics have been used for machining cast iron at very hi gh speeds. However, they have been found to be unsuitable for machinin g steel because of the severe wear of the ceramic cutting tools, which is thought to be mainly caused by the chemical dissolution of the cer amic in the chip at the high temperatures reached at the cutting edge. In this paper, a simulation test was carried out on a pin-on-disk tri bometer in order to investigate the effects of two antiwear additives on the friction and wear of Si3N4/1045 steel sliding contacts. Sliding speeds 1.6 m s(-1) and 3.2 m s(-1) were used, respectively, the selec ted test load was 117.6 N. The test results show that lubricants conta ining antiwear additives used in this test could greatly reduce the fr iction coefficient and wear rate of Si3N4 ceramics. Scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction spectroscopy were used for the analyses of the worn surfaces. Triboch emical reactions about the additives occurred on the frictional surfac es, the tribochemical films formed on the rubbing surfaces improved th e boundary lubrication conditions of the sliding contacts, the interdi ffusion and adhesion between the rubbing surfaces were prevented or we re greatly reduced.