Elastohydrodynamic lubrication between rolling and sliding ceramic cylinders: An experimental investigation

The present work focuses on the investigation of the influence of bulk ceramic materials on the behavior of elastohydrodynamically (EHD) lubricated line contacts. The materials (Al2O3), zirconium oxide (ZrO2) and aluminum nitride (AIN) are used. Comparative measurements were taken with steel disks made of 42CrMo4. Of primary important are the material parameters Young's modulus and thermal conductivity. The experimental variables pressure, temperature and oil film thickness in the EHD contact of a two disk test rig were measured with the aid of evaporated thin film sensors, As the results show an increase in the Young's modulus causes a clear increase of the pressure level. The oil film thickness distributions show a decline of the flattening width and of the constriction occurring at the contact outlet. The influence of the material with respect to its thermal conductivity dominates, above ail, in the region of the load transmitting contact zone. The transition from a good to a bad conductor of heat causes a rise in temperature, more prominent for materials with lower thermal conductivities. This leads to viscosity decrease causing clearly reduced oil film thicknesses in the contact. [S0742-4787(00)01404-1].