polishing performance of magnetorheological (MR) fluids prepared
with a variety of magnetic and non-magnetic ingredients was studied
on four types of initial surfaces for CVD ZnS flats from domestic
and foreign sources. The results showed that it was possible to
greatly improve smoothing performance of magnetorheological finishing
(MRF) by altering the fluid composition, with the best results obtained
for nanoalumina abrasive used with soft carbonyl iron and altered
MR fluid chemistry. Surface roughness did not exceed 20 nm p-v and
2 nm rms after removing 2 µm of material. The formation of
“orange peel” and the exposure of “pebble-like” structure inherent
in ZnS from the CVD process were suppressed. Removal of diamond
turning marks from a single point diamond turned (SPDT) surface
was also accomplished.
nanodiamond MR fluid
MR fluid chemistry reduced removal rates for CVD ZnS, but greatly
improved the ability to polish out the surface.
D. Jacobs, “Manipulating mechanics and chemistry in precision optics
finishing,” Science and Technology of Advanced Materials
8 153-157 (2007).
A. Kozhinova, H. J. Romanofsky, A. Maltsev, S. D. Jacobs, W. I.
Kordonski, and S. R. Gorodkin, "Minimizing Artifact Formation
in Magnetorheological Finishing of CVD ZnS Flats," Applied
Optics 44, pp. 4671-4677 (Aug., 2005).