Wettability behavior of textured and coated surfaces of bearing steel GCr15

Abstract

To address the challenge of insufficient lubrication on the inner ring of rolling bearings under high-speed conditions, a composite surface modification strategy integrating surface texturing, oleophilic coating, and an oleophobic barrier ring was proposed. A three-dimensional transient of spreading model of oil droplet was developed using the Volume of Fluid (VOF) multiphase approach, and the wetting behaviour of P20 lubricant was compared on four surfaces: smooth, textured, textured with oleophilic coating, and textured with both oleophilic coating and an oleophobic barrier ring. The results showed that the synergy of texturing and oleophilic coating markedly reduced the equilibrium contact angle from $40\circ$ to $18\circ$ , thereby accelerating spreading and improving central coverage. Static-pressure analysis further revealed that groove-induced pressure modulation and coating-enhanced capillary retention promoted lateral redistribution of the lubricant. The oleophobic barrier ring generated a boundary back-pressure effect that confined the droplet within the textured zone and delayed outward loss, sustaining larger wetted areas under moderate speeds. At higher speeds, however, centrifugal transport gradually dominated, reducing the effectiveness of these surface modifications and leading to partial lubricant loss. Overall, this strategy effectively enhanced lubricant retention and film stability under dynamic conditions, offering a feasible solution to mitigate starvation in high-speed bearing inner rings and extend component service life.