Tribological study of microbearings for MEMS applications
Document Type
Article
Publication Date
7-1-2005
Abstract
Microsleeve bearings intended for microrotational machinery were fabricated by X-ray lithography and Ni electroplating. Coated to the working surfaces of the bearings was a 900 nm 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 aselectrodeposited Ni microbearings, annealed Ni microbearings at 800°C, and W-C:H coated microbearings were investigated. Potential applications of the microbearings may involve very light contact pressure (5-30 MPa) and high sliding speed, such as micromotors and microturbines. Conventional pin-on disk test methods on top flat surfaces, (001) planes, cannot effectively predict tribological characteristics because these microbearings 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 microbearings. Test results of the W-C:H coated microbearings (wear characteristics and friction) are also presented. W-C:H coated microbearings 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. Copyright © 2005 by ASME.
Publication Source (Journal or Book title)
Journal of Tribology
First Page
537
Last Page
547
Recommended Citation
Kim, D., Cao, D., Bryant, M., Meng, W., & Ling, F. (2005). Tribological study of microbearings for MEMS applications. Journal of Tribology, 127 (3), 537-547. https://doi.org/10.1115/1.1924428