Proceedings Article | 14 May 2007
KEYWORDS: Magnetorheological finishing, Surface finishing, Optics manufacturing, Tungsten, Surface roughness, Magnetism, Scanning electron microscopy, Silicon carbide, Data modeling, Interferometers
We study material removal mechanisms of commercially available hard optical materials, with respect to
their micromechanical properties, as well as their response to different manufacturing techniques. The
materials of interest are heterogeneous materials such as Ni-based (nonmagnetic), Co-based (magnetic),
and binderless tungsten carbides, in addition to other hard optical ceramics such as ALON, polycrystalline
alumina (PCA), and silicon carbide (SiC). Our experimental work is performed in three stages,
emphasizing the contributions of each material’s microstructure to its mechanical response. In the first
stage, we identify and characterize material physical properties, such as E-Young's modulus, Hv-Vickers
hardness, and KIc- fracture toughness (either by microindentation techniques, previously published models,
or vendors’ data base). In the second stage, we examine the ability of these materials to be deterministically
microground and spotted with magnetorheological finishing (MRF). The evolution of the resulting surface
topography is studied using a contact profilometer, white light interferometry, scanning electron
microscopy, and atomic force microscopy. In the third stage, we demonstrate that subsurface damage
(SSD) depth can be estimated by correlating surface microroughness measurements, specifically, the peakto-
valley (p-v) microroughness, to the amount of material removed by an MRF spot.
