Vickers Indentation Fracture in Optical Glass Compositions

Wilantewicz, Trevor E.; Varner, James R.

doi:10.1002/9781118144152.ch12

Cited by 3 publications

(2 citation statements)

References 23 publications

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“…Experimentally, we observed α ∼ 41 • and 34 • for a-SiO 2 (ν = 0.15) and a borosilicate glass (ν = 0.195), respectively, for a 98.1 N Vickers indent (figure 16). This is in good agreement with the values obtained by Wilantewicz & Varner [60] [63]. For vitreous carbon (ν ∼ 0.27-0.29) the angle the cone (ball indentation test) makes with the surface is 22.5 • on average [64].…”

Section: (D) the Effect Of High Pressuresupporting

confidence: 91%

Driving force for indentation cracking in glass: composition, pressure and temperature dependence

Rouxel

2015

Phil. Trans. R. Soc. A.

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The occurrence of damage at the surface of glass parts caused by sharp contact loading is a major issue for glass makers, suppliers and end-users. Yet, it is still a poorly understood problem from the viewpoints both of glass science and solid mechanics. Different microcracking patterns are observed at indentation sites depending on the glass composition and indentation cracks may form during both the loading and the unloading stages. Besides, we do not know much about the fracture toughness of glass and its composition dependence, so that setting a criterion for crack initiation and predicting the extent of the damage yet remain out of reach. In this study, by comparison of the behaviour of glasses from very different chemical systems and by identifying experimentally the individual contributions of the different rheological processes leading to the formation of the imprint-namely elasticity, densification and shear flow-we obtain a fairly straightforward prediction of the type and extent of the microcracks which will most likely form, depending on the physical properties of the glass. Finally, some guidelines to reduce the driving force for microcracking are proposed in the light of the effects of composition, temperature and pressure, and the areas for further research are briefly discussed.

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Section: (D) the Effect Of High Pressuresupporting

confidence: 91%

Driving force for indentation cracking in glass: composition, pressure and temperature dependence

Rouxel

2015

Phil. Trans. R. Soc. A.

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“…A semicircular median crack is typically assumed to pop in underneath the indentation, although the crack type and formation sequence is quite complicated and varies dramatically with material. 98,99,100 The residual stress damage zone is approximated by a point force acting to open the crack. The stress intensity factor KIr acting on the flaw…”

Section: -62mentioning

confidence: 99%

NIST Recommended Practice Guide Fractography of Ceramics and Glasses

Quinn¹

2016

108

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Energetics of glass fragmentation: Experiments on synthetic and natural glasses

Kolzenburg

Russell

Kennedy

2013

Geochem Geophys Geosyst

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[1] Natural silicate glasses are an essential component of many volcanic rock types including coherent and pyroclastic rocks; they span a wide range of compositions, occur in diverse environments, and form under a variety of pressure-temperature conditions. In subsurface volcanic environments (e.g., conduits and feeders), melts intersect the thermodynamically defined glass transition temperature to form glasses at elevated confining pressures and under differential stresses. We present a series of room temperature experiments designed to explore the fundamental mechanical and fragmentation behavior of natural (obsidian) and synthetic glasses (Pyrex TM ) under confining pressures of 0.1-100 MPa. In each experiment, glass cores are driven to brittle failure under compressive triaxial stress. Analysis of the loaddisplacement response curves is used to quantify the storage of energy in samples prior to failure, the (brittle) release of elastic energy at failure, and the residual energy stored in the post-failure material. We then establish a relationship between the energy density within the sample at failure and the grain-size distributions (D-values) of the experimental products. The relationship between D-values and energy density for compressive fragmentation is significantly different from relationships established by previous workers for decompressive fragmentation. Compressive fragmentation is found to have lower fragmentation efficiency than fragmentation through decompression (i.e., a smaller change in D-value with increasing energy density). We further show that the stress storage capacity of natural glasses can be enhanced (approaching synthetic glasses) through heat treatment.

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Vickers Indentation Fracture in Optical Glass Compositions

Cited by 3 publications

References 23 publications

Driving force for indentation cracking in glass: composition, pressure and temperature dependence

Driving force for indentation cracking in glass: composition, pressure and temperature dependence

NIST Recommended Practice Guide Fractography of Ceramics and Glasses

Energetics of glass fragmentation: Experiments on synthetic and natural glasses

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