Modeling and Analysis of the Tribological Evaluation of Bearing Materials under the Influence of Nano Based Marine Lubricant Using D-Optimal Design

Abstract

The journal bearing is considered to be an important element of all rotating machinery. The journal and bearing are separated by a thin film lubricating oil, thus preventing metal-to-metal contact. In general, the journal bearing is a significant tribological component next to the piston ring-cylinder liner tribo pair in any of the marine diesel engines. The friction and wear of the journal bearing system is reduced by proper lubricating oil. The usage of fuel oil was considerably increased due to the rapid development in marine diesel engine which increases the operating cost. The power of the marine diesel engine is greatly improved by reducing frictional power which in turn rely on the tribological behavior between bearing materials and lubricants combination. In the present study, Response Surface Methodology (RSM) based D-optimal design was used to estimate the tribological behavior of various journal bearing materials (Bronze, AlSn40 and White metal) under the influence of nano based marine lubricants (SN 500 base oil). The pin on disc tribometer was used to estimate the frictional and wear characteristics of the various journal bearing materials lubricated with SN 500 base oil containing various concentrations of nano CuO. The experiments were conducted by selecting a various load and speed as numerical factors and journal bearing materials/nano based marine lubricants as categorical factors to perform the tribological behavior such as frictional coefficient and specific wear rate. From the present study, it was observed that the bronze bearing material with SN 500 base oil containing 0.5 wt% nano CuO showed the minimum frictional coefficient of 0.072 and minimum specific wear rate of 1.54X10-10mm3/Nm as compared with the other bearing materials/lubricating oil combination for a sliding speed of 2 m/s and bearing load of 100 N. Additionally the scanning electron microscopy (SEM) examination was conducted to estimate the worn surfaces of the tested pin (bearing) material, and it is showed that the bronze bearing material lubricated with the SN 500 base oil containing 0.5 wt% nano CuO is smoother wear surface than the other bearing materials/lubricants combination.