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Title: Sub-surface mechanical damage distributions during grinding of fused silica

Abstract

The distribution and characteristics of surface cracking (i.e. sub-surface damage or SSD) formed during standard grinding processes has been investigated on fused silica glass. The SSD distributions of the ground surfaces were determined by: (1) creating a shallow (18-108 {micro}m) wedge/taper on the surface by magneto-rheological finishing; (2) exposing the SSD by HF acid etching; and (3) performing image analysis of the observed cracks from optical micrographs taken along the surface taper. The observed surface cracks are characterized as near-surface lateral and deeper trailing indent type fractures (i.e., chatter marks). The SSD depth distributions are typically described by a single exponential distribution followed by an asymptotic cutoff in depth (c{sub max}). The length of the trailing indent is strongly correlated with a given process. Using established fracture indentation relationships, it is shown that only a small fraction of the abrasive particles are being mechanically loaded and causing fracture, and it is likely the larger particles in the abrasive particle size distribution that bear the higher loads. The SSD depth was observed to increase with load and with a small amount of larger contaminant particles. Using a simple brittle fracture model for grinding, the SSD depth distribution has been related tomore » the SSD length distribution to gain insight into ''effective'' size distribution of particles participating in the fracture. Both the average crack length and the surface roughness were found to scale linearly with the maximum SSD depth (c{sub max}). These relationships can serve as useful rules-of-thumb for nondestructively estimating SSD depth and to identify the process that caused the SSD. In certain applications such as high intensity lasers, SSD on the glass optics can serve as a reservoir for minute amounts of impurities that absorb the high intensity laser light and lead to subsequent laser-induced surface damage. Hence a more scientific understanding of SSD formation can provide a means to establish recipes to fabricate SSD-free, laser damage resistant optical surfaces.« less

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
898584
Report Number(s):
UCRL-JRNL-217445
TRN: US200706%%220
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Non-Crystalline Solids, vol. 352, N/A, October 30, 2006, pp. 5601-5617
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 42 ENGINEERING; ABRASIVES; DEPTH; DISTRIBUTION; ETCHING; FRACTURES; GLASS; GRINDING; IMPURITIES; LASERS; OPTICS; PARTICLE SIZE; ROUGHNESS; SILICA; SPATIAL DISTRIBUTION

Citation Formats

Suratwala, T I, Wong, L L, Miller, P E, Feit, M D, Menapace, J A, Steele, R A, Davis, P A, and Walmer, D. Sub-surface mechanical damage distributions during grinding of fused silica. United States: N. p., 2005. Web.
Suratwala, T I, Wong, L L, Miller, P E, Feit, M D, Menapace, J A, Steele, R A, Davis, P A, & Walmer, D. Sub-surface mechanical damage distributions during grinding of fused silica. United States.
Suratwala, T I, Wong, L L, Miller, P E, Feit, M D, Menapace, J A, Steele, R A, Davis, P A, and Walmer, D. Mon . "Sub-surface mechanical damage distributions during grinding of fused silica". United States. doi:. https://www.osti.gov/servlets/purl/898584.
@article{osti_898584,
title = {Sub-surface mechanical damage distributions during grinding of fused silica},
author = {Suratwala, T I and Wong, L L and Miller, P E and Feit, M D and Menapace, J A and Steele, R A and Davis, P A and Walmer, D},
abstractNote = {The distribution and characteristics of surface cracking (i.e. sub-surface damage or SSD) formed during standard grinding processes has been investigated on fused silica glass. The SSD distributions of the ground surfaces were determined by: (1) creating a shallow (18-108 {micro}m) wedge/taper on the surface by magneto-rheological finishing; (2) exposing the SSD by HF acid etching; and (3) performing image analysis of the observed cracks from optical micrographs taken along the surface taper. The observed surface cracks are characterized as near-surface lateral and deeper trailing indent type fractures (i.e., chatter marks). The SSD depth distributions are typically described by a single exponential distribution followed by an asymptotic cutoff in depth (c{sub max}). The length of the trailing indent is strongly correlated with a given process. Using established fracture indentation relationships, it is shown that only a small fraction of the abrasive particles are being mechanically loaded and causing fracture, and it is likely the larger particles in the abrasive particle size distribution that bear the higher loads. The SSD depth was observed to increase with load and with a small amount of larger contaminant particles. Using a simple brittle fracture model for grinding, the SSD depth distribution has been related to the SSD length distribution to gain insight into ''effective'' size distribution of particles participating in the fracture. Both the average crack length and the surface roughness were found to scale linearly with the maximum SSD depth (c{sub max}). These relationships can serve as useful rules-of-thumb for nondestructively estimating SSD depth and to identify the process that caused the SSD. In certain applications such as high intensity lasers, SSD on the glass optics can serve as a reservoir for minute amounts of impurities that absorb the high intensity laser light and lead to subsequent laser-induced surface damage. Hence a more scientific understanding of SSD formation can provide a means to establish recipes to fabricate SSD-free, laser damage resistant optical surfaces.},
doi = {},
journal = {Journal of Non-Crystalline Solids, vol. 352, N/A, October 30, 2006, pp. 5601-5617},
number = ,
volume = ,
place = {United States},
year = {Mon Nov 28 00:00:00 EST 2005},
month = {Mon Nov 28 00:00:00 EST 2005}
}