A Study on the Surface Fatigue of a Line Contact System and the Tribological Behavior under the Lubrication with a New Type EP Additive

• Main Authors: Jung Chung Lin, 林榮聰
• Other Authors: Jen Fin Lin
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/72078546169566448402

碩士 === 國立成功大學 === 機械工程學系 === 87 === The research topics of this thesis lie in two areas. Firstly, a gear/cam adapter was employed to study the tribological behavior of line-contact lubrication with low-phosphorus, extreme-pressure additives. Secondly, the lubrication behavior of two different roughness rollers was investigated in terms of wear rate, friction coefficient, oil temperature, chemical reaction in thin films as well as various additive concentration. In first par of this thesis, the Electrical Contact Resistance (ECR) is used to detect the chemical reaction during the wear test. The surface roughness and wear rate before and after the wear test is also measured. Many instruments like the Atomic Force Microscopy (AFM) is implemented to observe the growth of the chemical film; the Optical Microscopy (OM) is used to see wear surface, and WDS, ESCA and AES are also used for chemical reaction. As the experimental results shown, the ECR of the smooth roller rises as the temperature goes up while there is no dramatic change for the rough roller. The average friction coefficients of the smooth roller will rise initially and then stabilizes as the oil temperature and ECR stabilize. Based on the observation of the ECR variation and the wear rate, the optimal additive concentration is 0.07wt%~0.08wt%. Also, for chemical reactive potential, under different operating conditions, the highest additive concentration (0.09wt%) has the highest chemical reactive potential. In second part of this thesis, the surface fatigue life is evaluated for line-contact element under rolling/sliding. The parameters like load, speed, roughness, additives and viscosity of the lubrication oil are the main controlling factors. As the results indicate, the smooth roller and the use of high viscosity lubrication oil will improve the fatigue life greatly. The shear stress is larger on the rough roller and the angle of the crack initiation with respect to the surface is smaller but the influence underneath the surface is shallow. The smooth roller shows the opposite trends. As a result, the occurrence of the pitting is deeper under the surface for smooth rollers. From the observation of the wear debris, the mechanism of the occurrence of spherical debris comes from the hydrostatic pressure.