Study on tribological properties of novel biomimetic material for water-lubricated stern tube bearing

As one important supporting component in ship propulsion systems, the water-lubricated stern tube bearing has great effects on shipping navigation safety. However, it is difficult to ensure the good lubrication for water-lubricated stern tube bearings under low speed working conditions. The lignum vitae have the significant self-lubricated performance on stern tube bearings. In this study, the present situation of the biomimetic application was introduced. The components of lignum vitae were analyzed to investigate the corresponding mechanism of self-lubricated. The biomimetic materials (0%, 0.5%, 1%, 3% guaiacum and high-density polyethylene (HDPE)) are designed and prepared based on the properties of lignum vitae. A series of experimental tests were then conducted in a specially designed tester to investigate the tribological characteristics of the biomimetic materials. The comparison analyses of the friction coefficients, wear mass losses and the worn surfaces were conducted under different concentration of biomimetic materials and running conditions. The analysis results show that there were significant differences in the tribological properties of the rubbing pairs in different concentration of guaiacum. The wear performance of the biomimetic material with 0.5% concentration of guaiacum was superior to that of other concentrations. In addition, the biomimetic material with 0.5% concentration of guaiacum was the most effective to improve the wear properties at the low sliding velocity of 0.11 m/s. It is believed that the knowledge gained in this study will provide a novel approach for wear reduction and lubrication performance improvement of water-lubricated stern tube bearing in ships.