Lubricant Effects in the Transition from Boundary to Microelastohydrodynamic Lubrication |
| |
Authors: | Zunde Yang Yip-Wah Chung Herbert S. Cheng |
| |
Affiliation: | 1. Northwestern University, Center for Engineering Tribology, Department of Materials Science and Engineering , Evanston, Illinois, 60208;2. Northwestern University, Center for Engineering Tribology, Department of Mechanical Engineering , Evanston, Illinois, 60208 |
| |
Abstract: | Lubricant effects in the friction transition from boundary to microelastohydrodynamic lubrication were investigated by using a ballon-flat tribotester at sliding speeds from 0.02 to 0.88 mm/sec. Three lubricants—cyclophosphazine (X-IP), poly-alpha-olefin (PAO) and Z-DOL—were used, in this investigation. When X-IP was used at room temperature, a drop in friction coefficient from 0.22 to 0.12 at sliding speeds ≥0.10 mm/sec. (an unusually low speed) was observed, accompanied by a rise in the contact electrical resistance across the ball-fiat interface. The friction drop did not occur at temperatures ≥100°C. The friction transition was achieved at lower speeds when sliding perpendicular to the surface roughness texture. No transition occurred when PAO and Z-DOL were substituted as the lubricant. The latter him lubricants were working in the boundary lubrication regime as indicated by the contact resistance measurement. |
| |
Keywords: | |
|
|