To suggest wear condition of DLC/DLC contact from wear particles diagnosis, wear particles generated from DLC/DLC contact under lubrication, we leached after using oil to collect these particles from lubrication by PTFE filtration, then, we clarified a possibility of severe wear condition classification. DLC coated cylinder and DLC coated disk were slid under different lubrication temperature (25, 80 and 120ºC). The wear particles on PTFE filter was observed by optical microscope and scanning electron microscope to measure total wear particle area (mm²). The specific wear rate (mm³/Nm) of DLC coating on cylinder was calculated by wear scar width by geometrically, then, we calculated average wear particle thickness (nm) from specific wear rate, area, normal load and sliding distance. From the results, DLC wear particles were roughly divided two types as black color particle with 1-10 µm diameter and thin transparent particle with 10-15 µm diameter. In the case of 120ºC lubrication condition, Raman analysis to wear particle indicated less graphitization rather than 25 and 80ºC. Furthermore, wear particle thickness at 120ºC indicated large as much as 25 and 80ºC.

In this paper, the relationship between supply oil quantity and stability of oil film journal bearings are described. Experiments regarding the stability of the journal bearing under vicinity of critical supply oil quantity are conducted. In order to clarify the mechanism of the hysteresis characteristic, the journal lissajous, vibrations and frequencies are measured and the cavitation generated in the bearing clearance were observed. On the other hand, same experiments were conducted regarding inertia effect which appears in case of increasing and decreasing of rotational speed and we compared it with the above experiments. As a result, the different stabilization tendencies were shown between decrease cases of supply oil quantity and rotational speed. From the results of cavitation observation, it is considered that the reason for different stabilization tendency is due to difference of cavitation regions generated in the journal bearing clearance.