Ion implantation into race surfaces of aerospace ball bearings in a plasma immersion configuration

Plasma immersion ion implantation (PIII) is an effective technique to improve the surface properties of industrial components possessing an irregular shape, such as ball bearings used in the aerospace industry. The implant uniformity and efficiency along both the inner and outer races of a ball bearing assembly is investigated experimentally and theoretically. We study the sample placement as well as different PIII processing conditions. The use of a three-dimensional (3-D) model to investigate the influence of the sample stage on the implantation efficiency and dose uniformity is described. Based on the experimental results, under typical PIII conditions, the dose variation along the outward-facing groove of the inner ring of the ball bearing assembly is 60%, whereas that along the inward-facing groove of the outer ring is 51%. By using a shorter pulsewidth and higher plasma density, the nonuniformity is improved to about 35%, which is acceptable to the aerospace industry. The experimental observations are in agreement with simulation results, and the improvement can be attributed to the better conformability of the plasma sheath to the race surface. Our results demonstrate the viability of PIII to enhance the surface properties of both the inner and outer rings of industrial ball bearings.