The distribution of subsurface damage in fused silica

Miller, Phil; Suratwala, Tayyab; Wong, Lana L.; Feit, Michael D.; Menapace, Joseph A.; Davis, Paul; Steele, R.

doi:10.1117/12.638821

Cited by 126 publications

(92 citation statements)

References 14 publications

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“…In our previous studies, the characteristics and statistical distribution of SSD as a function of different grinding processes using a polished taper technique has been measured and analyzed [14][15][16]. These results suggested that only a small fraction (1 out of tens of thousands of particles) of the abrasive particles were participating in the material removal by comparing the measured crack depth that with that expected from static indentation models.…”

Section: Introductionmentioning

confidence: 92%

“…1). Details of this characterization technique to determine SSD depth and length distributions are provided elsewhere [14][15][16]. Photographs of the grinding setup is shown in Fig.…”

Section: Ground Samplesmentioning

confidence: 99%

“…Hunter [22] and Ting [23] have shown approaches to account for the surface displacement. Ting's approach provides an analytical expression for the total displacement in terms of the contact zone radius and can be applied to high strain which is given by: (16) where r is radial distance away from the center of the particle. Now consider a rogue particle penetrating into the lap as described in Fig.…”

Section: Scratch Characteristics and Viscoelastic Modelmentioning

confidence: 99%

“…Figure 4 shows an optical micrograph of a ground surface after the rubble-like surface has been removed, illustrating the typical cracks observed on a ground surface. The length or size of these trailing indents cracks have been found to scale with the size of the abrasive particle used for grinding [14,16]. was used instead of crack number density to describe the SSD density because the intersection of cracks near the surface causes a significant uncertainty in the crack number density.…”

Section: Rogue Particles During Grindingmentioning

confidence: 99%

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Effect of rogue particles on the sub-surface damage of fused silica during grinding/polishing

Suratwala

Steele

Feit

et al. 2008

Journal of Non-Crystalline Solids

128

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The distribution and characteristics of surface cracks (i.e., sub-surface damage or scratching) on fused silica formed during grinding/polishing resulting from the addition of rogue particles in the base slurry has been investigated. Fused silica samples (10 cm diameter x 1 cm thick) were: 1) ground by loose abrasive grinding (alumina particles 9-30 µm) on a glass lap with the addition of larger alumina particles at various concentrations with mean sizes ranging from 15-30 µm, or 2) polished (using 0.5 µm cerium oxide slurry) on various laps (polyurethanes pads or pitch) with the addition of larger rogue particles (diamond (4-45 µm), pitch, dust, or dried Ceria slurry agglomerates) at various concentrations. For the resulting ground samples, the crack distributions of the as-prepared surfaces were determined using a polished taper technique. The crack depth was observed to: 1) increase at small concentrations (>10 -4 fraction) of rogue particles; and 2) increase with rogue particle concentration to crack depths consistent with that observed when grinding with particles the size of the rogue particles alone. For the polished samples, which were subsequently etched in HF:NH 4 F to expose the surface damage, the resulting scratch properties (type, number density, width, and length) were characterized. The number density of scratches increased exponentially with the size of the rogue diamond at a fixed rogue diamond concentration suggesting that larger particles are more likely to lead to scratching. The length of the scratch was found to increase with rogue particle size, increase with lap viscosity, and decrease with applied load. At high diamond concentrations, the type of scratch transitioned from brittle to ductile and the length of the scratches dramatically increased and extended to the edge of the optic. The observed trends can explained semi-quantitatively in terms of the time needed for a rogue particle to penetrate into a viscoelastic lap. The results of this study provide useful insights and 'rules-of-thumb' relating scratch characteristics observed on surfaces during optical glass fabrication to the characteristics rogue particles causing them and their possible source.

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Section: Introductionmentioning

confidence: 92%

“…1). Details of this characterization technique to determine SSD depth and length distributions are provided elsewhere [14][15][16]. Photographs of the grinding setup is shown in Fig.…”

Section: Ground Samplesmentioning

confidence: 99%

Section: Scratch Characteristics and Viscoelastic Modelmentioning

confidence: 99%

Section: Rogue Particles During Grindingmentioning

confidence: 99%

See 2 more Smart Citations

Effect of rogue particles on the sub-surface damage of fused silica during grinding/polishing

Suratwala

Steele

Feit

et al. 2008

Journal of Non-Crystalline Solids

128

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“…The details of how these rules were developed are described in each of the references included in this summary (1)(2)(3)(4)(5)(6)(7)(8)(9). Figure 2 provides as a summary of some of the more commonly used rules-of-thumbs that have been developed in this study.…”

mentioning

confidence: 99%

FY07 LDRD Final Report A Fracture Mechanics and Tribology Approach to Understanding Subsurface Damage on Fused Silica during Grinding and Polishing

Suratwala¹,

Miller²,

Menapace³

et al. 2008

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The objective of this work is to develop a solid scientific understanding of the creation and characteristics of surface fractures formed during the grinding and polishing of brittle materials, specifically glass. In this study, we have experimentally characterized the morphology, number density, and depth distribution of various surface cracks as a function of various grinding and polishing processes (blanchard, fixed abrasive grinding, loose abrasive, pitch polishing and pad polishing). Also, the effects of load, abrasive particle (size, distribution, foreign particles, geometry, velocity), and lap material (pitch, pad) were examined. The resulting data were evaluated in terms of indentation fracture mechanics and tribological interactions (science of interacting surfaces) leading to several models to explain crack distribution behavior of ground surfaces and to explain the characteristics of scratches formed during polishing. This project has greatly advanced the scientific knowledge of microscopic mechanical damage occurring during grinding and polishing and has been of general interest. This knowledge-base has also enabled the design and optimization of surface finishing processes to create optical surfaces with far superior laser damage resistance.There are five major areas of scientific progress as a result of this LDRD. They are listed in Figure 1 and described briefly in this summary below. The details of this work are summarized through a number of published manuscripts which are included this LDRD Final Report.In the first area of grinding, we developed a technique to quantitatively and statistically measure the depth distribution of surface fractures (i.e., subsurface damage) in fused silica as function of various grinding processes using mixtures of various abrasive particles size distributions. The observed crack distributions were explained using a model that extended known, single brittle indentation models to an ensemble of loaded, sliding particles. The model illustrates the importance of the particle size distribution of the abrasive and its influence on the resulting crack distribution. The results of these studies are summarized in references 1-7.In the second area of polishing, we conducted a series of experiments showing the influence of rogue particles (i.e., particles in the polishing slurry that are larger than base particles) on the creation of scratches on polished surfaces. Scratches can be thought of a as a specific type of sub-surface damage. The characteristics (width, length, type of fractures, concentration) were explained in terms of the rogue particle size, the rogue particle material, and the viscoelastic properties of the lap. The results of these studies are summarized in references 6-7.In the third area of etching, we conducted experiments aimed at understanding the effect of HF:NH 4 F acid etching on surface fractures on fused silica. Etching can be used as a method: a) to expose sub-surface mechanical damage, b) to study the morphology of specific mechanical damage occur...

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Surface Quality

2018

Materials Science and Technology of Optical Fabrication

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The distribution of subsurface damage in fused silica

Cited by 126 publications

References 14 publications

Effect of rogue particles on the sub-surface damage of fused silica during grinding/polishing

Effect of rogue particles on the sub-surface damage of fused silica during grinding/polishing

FY07 LDRD Final Report A Fracture Mechanics and Tribology Approach to Understanding Subsurface Damage on Fused Silica during Grinding and Polishing

Surface Quality

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