Friction and wear characteristics of a Ti-containing diamond-like carbon coating with an SRV tester at high contact load and elevated temperature

摘要

The friction and wear characteristics of a Ti-containing diamond-like carbon (Ti-DLC) coating have been evaluated with a Schwingungs Reibung und Verschleiss (SRV) tester when reciprocating sliding against a steel ball and a CrN-coated pin at high contact load and elevated temperature under a boundary-lubricated condition. The Ti-DLC coatings exhibit a friction coefficient of 0.06-0.12 and a wear rate of 1.99x10(-10) to 9.5x10(-7) mm(3)/N m, depending on the counterfaces, load and temperature. The Ti-DLC/CrN-coated pin pair shows a low friction coefficient than the Ti-DLC/steel ball pair under the identical wear conditions. Increasing the test temperature reduces the coefficient of friction and, however, clearly increases the wear rate of the Ti-DLC coatings at 20 N. At 50 N and 150 degrees C, the Ti-DLC coating was removed completely and the wear was applied to the substrate. At below 100 degrees C, the wear mechanism of the Ti-DLC coatings is dominated by surface polishing effects. At 150 degrees C, brittle fracture, delamination, partial graphitization, and tribo-chemical reactions are found in the tribo-contact areas. The formation of iron oxides on worn surfaces of the Ti-DLC coatings at 150 degrees C is attributed to the dissolved oxygen in the oil lubricant and the tribo-chemical reactions. Furthermore, these friction and wear data have been compared quantitatively with pure DLC coatings and multilayered VTiN coatings under the identical wear conditions. (c) 2004 Elsevier B.V. All rights reserved.