Improving running-in quality of Babbitt alloy using h-BN as oil additives

Babbitt alloy, the common material of the main bearing of marine diesel engines , is prone to adhesive wear in the running-in process. It will shorten the service life and affect the stability of the bearing. To improve the running-in quality of Babbitt alloy, the hexagonal boron nitride (h-BN) was used as a lubricating oil additive. The running-in test was conducted by adding the h-BN with a particle size of 0.1 μm, 0.5 μm, 1 μm, and 5 μm into the base oil. The friction coefficient , wear topography, and recurrence parameters were used to assess the effect of h-BN on running-in quality. The results show that h-BN can reduce friction coefficient , enhance the stability of the friction system and improve surface quality after the running in. The h-BN with large particle size mainly plays the micro-bearing, interlayer sliding, and polishing effects. The h-BN with small particle size plays the micro-bearing, moderating impact, and surface mending effects. According to the actual conditions, one can select the appropriate particle sizes to improve running-in quality.