Micro sleeve bearings intended for micro rotational machinery were fabricated by X-ray lithography and Ni electroplating. Coated to the working surfaces of the bearings was a 900nm thick uniform tungsten hydrocarbon (W-C:H) coating using an inductively coupled plasma (ICP) assisted, hybrid chemical vapor deposition (CVD)/physical vapor deposition (PVD) tool. Tribological characteristics and mechanical properties of as-electrodeposited Ni micro bearings, annealed Ni micro bearings at 800°C, and W-C:H coated micro bearings were investigated. Potential applications of the micro bearings may involve very light contact pressure (5∼30MPa) and high sliding speed, such as micro motors and micro turbines. Conventional pin-on disc test methods on top flat surfaces, (001) planes, cannot effectively predict tribological characteristics because these micro bearings use the sidewall (110 plane) as a working surface. A special micro wear tester and friction tester were developed. Surface morphologies of new and worn bearing surfaces were studied using SEM. Raman Spectroscopy and X-ray Photoelectron Spectroscopy (XPS) characterized the W-C:H coated micro bearings. Test results of the W-C:H coated micro bearings (wear characteristics and friction) are also presented. W-C:H coated micro bearings had much lower wear rate than uncoated bearings. During the wear test, a transfer layer formed on the counter steel shaft even under very small contact pressure, leading to low steady state friction and high wear resistance.

This content is only available via PDF.
You do not currently have access to this content.