Surface-texture evolution of different chemical-vapor-deposited zinc sulfide flats polished with various magnetorheological fluids

Here we describe the MRF process of polishing four CVD ZnS substrates, manufactured by four different vendors, with conventional MR fluid at pH 10 and zirconia-coated-CI (carbonyl iron) MR fluids at pH 4, 5, and 6. We report on the surface-texture evolution of the substrates as they were MRF polished with the different fluids. We show that performances of the zirconia-coated-CI MR fluid at pH 4 are significantly higher than that of the same fluid at pH levels of 5 and 6 and moderately higher than that of a conventional MR fluid at pH 10. An improvement in surface-texture variability from part to part was also observed with the pH 4 MR fluid.