Nanoplastic removal function and the mechanical nature of colloidal silica slurry polishing
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2018-10-19 |
| Journal | Journal of the American Ceramic Society |
| Authors | Nan Shen, Eyal Feigenbaum, Tayyab I. Suratwala, William A. Steele, Lana L. Wong |
| Institutions | Lawrence Livermore National Laboratory |
| Citations | 6 |
Abstract
Section titled āAbstractāAbstract The nanomechanical deformations on a broad range of optical material surfaces (single crystals of Al 2 O 3 [sapphire], SiC, Y 3 Al 5 O 12 [ YAG ], CaF 2 , and LiB 3 O 5 [ LBO ]; a SiO 2 -Al 2 O 3 -P 2 O 5 -Li 2 O glassāceramics [Zerodur]; and glasses of SiO 2 :TiO 2 [ ULE ], SiO 2 [fused silica], and P 2 O 5 -Al 2 O 3 -K 2 O-BaO [Phosphate]) near the elasticāplastic load boundary have been measured by nanoindentation and nanoscratching to mimic the nanoplastic removal caused by a single slurry particle during polishing. Nanoindenation in air was performed to determine the workpiece hardness at various loads using a commercial nanoindenter with a Berkovich tip. Similarly, an atomic force microscope ( AFM ) with a stiff diamond coated tip (150 nm radius) was used to produce nanoplastic scratches in air and aqueous environments over a range of applied loads (~20ā170 Ī¼N). The resulting nanoplastic deformation of the nanoscratches were used to calculate the removal function (i.e., depth per pass) which ranged from 0.18 to 3.6 nm per pass for these materials. A linear correlation between the nanoplastic removal function and the polishing rate (using a fixed polishing process with colloidal silica slurry on a polyurethane pad) of these materials was observed implying that: (a) the polishing mechanism using colloidal silica slurry can be dominated by mechanical rather than chemical interactions; and (b) the nanoplastic removal function, as opposed to interface particle interactions, is the controlling factor for the polishing material removal rate. Furthermore, this correlation is consistent with the Ensemble Hertzian MultiāGap ( EHMG ) microscopic material removal rate model described previously. The nanoplastic removal depth was also found to correlate to the measured nanoindentation hardness ( H 1 ) of the optical material, scaling as H 1 ā3.5 . Twoādimensional (2D) finite element analysis simulations of nanoindentation showed a similar nonlinear dependence of plastic deformation with the workpiece material hardness. The findings of this study are used to determine an effective Preston coefficient for the material removal rate expression and enhance the predictive nature of the nanoplastic polishing rate for various materials utilizing their material properties.
Tech Support
Section titled āTech SupportāOriginal Source
Section titled āOriginal SourceāReferences
Section titled āReferencesā- 2018 - Influence of partical charge on the material removal rate during chemical polishing