Synergistic lubrication mechanisms of AISI 4140 steel in dual lubrication systems of multi-solid coating and oil lubrication

In order to improve tribological properties of AISI 4140 steel (AS) for dry/starved lubrication, AS biomimetic self-lubricating material (AS-SACT) was prepared by filling SnAgCu-TiC into biomimetic microtextures. Compared with AS, the friction coefficient of AS-SACT was reduced by 5.34% and wear depth was reduced by 62.39% in starved lubrication. Tribological properties of AS-SACT in starved oil are close to those of full oil lubrication. Under starved lubrication, the precipitated lubricant spreads into a 2.2 µm solid film on contact surface. In addition, the lubricant precipitation area forms a 'storage area' for storing lubricating oil and wear debris. The synergistic lubrication effect of multi-solid coating and oil lubrication makes AS-SACT have excellent anti-friction and wear-resisting effect.