Research on the influence factors of palygorskite nano-particles forming self-repairing film in steel-steel pair

The palygorskite nano-particles were used as lubricant additives with mass fraction of 2% and 4% respectively to prepare two kinds of lubricating oil samples. The friction and wear properties of 45# steel-steel pairs lubricated by the lubricating oil samples were tested on MMU-10G friction and wear tester. The morphological changes and self-repairing film forming condition of the worn surfaces were investigated by means of scanning electron microscopy (SEM) after 40 hours´ running. The composition changes of friction surface were detected by EDX in order to infer the basic component of self repairing films. The wear loss of samples was determined by weighing method in order to evaluate the antiwear property of lubricating oil system. The results show that the self-repairing film with speckles can be formed under the discontinuous running mode; otherwise, the continuous and intact self-repairing film can be seen while the palygorskite nano-particles content reached 4%. Both the films contain characteristic elements of the palygorskite. The later causes the wear loss and friction coefficient to be decreased by 56% and 20% respectively compare with the contrast group without palygorskite nano-particles. It also leads to the decrease of wear loss reaching to 37% in comparison with the former and plays a role in improving the properties of antifriction and wear resistance.