Improving wear resistance of helicopter gear under extreme lubrication conditions through LSPwc surface modification

A sudden lubrication failure in the helicopter transmission system will cause severe wear and mechanical breakdown of gear components within a short period of time, posing a significant threat to flight safety. This research fabricated periodic micro-textures on the surface of AISI 9310 gear steel through laser shock peening without coatings (LSPwc), and systematically investigated the lubrication retention mechanism under high centrifugal force and anti-wear behavior under different lubricated conditions. Texture patterns prepared by LSPwc enhanced the lubrication retention through micro-pit storage function and surface tension, resulting in a 2.8-fold increase in residual lubricant amount after 30 min of centrifugation compared to the untreated. LSPwc textured structure after optimization of the process could extend the boundary lubrication state by more than 30 min, reduce the volumetric mass loss due to wear by 72%, and delay the failure time by more than 660 s even without lubrication. Textured cavities separated the oil film, captured the wear debris and formed a boundary lubrication film. Combined with the gradient microstructure strengthening effect these cavities jointly inhibited the sharp increase in the friction coefficient and the diffusion of oxidative adhesion.