A glass with high crack initiation load: Role of fictive temperature-independent mechanical properties

Competing Indentation Deformation Mechanisms in Glass Using Different Strengthening Methods

“…For the sample with HFV, very little residual stress is observed for almost all the initial stress levels except the sample under initial tension. More indentation-induced densification leads to lower tensile stress, which is in agreement with experimental observations (Gross and Tomozawa, 2008a,b;Gross et al, 2009;Kato et al, 2010). For the sample with LFV content, large residual tensile stress shows up after unloading.…”

“…Emerging demand for stronger and lighter car windshields and other novel transparent structural materials further stimulates a need for deeper understanding and improvement of glass strengthening techniques. Studies of contact cracking (Lawn and Wilshaw, 1975;Ostojic and McPherson, 1987;Cook and Pharr, 1990) date back at least one century (Johnson, 1985;Lawn, 1998) and tremendous progress has been achieved to understand the shear flow, densification, and cracking under indentation in brittle solids (Lawn and Swain, 1975;Lawn and Wilshaw, 1975;Marshall and Lawn, 1978;Hagan, 1979;Lawn et al, 1983;Johnson, 1985;Ostojic and McPherson, 1987;Cook and Pharr, 1990;Lawn, 1998Lawn, , 2004Perriot et al, 2006;Gross and Tomozawa, 2008a,b,c;Gross et al, 2009;Kato et al, 2010;Gross, 2012a;Kassir-Bodon et al, 2012;Niu et al, 2012;Tran et al, 2012;Kjeldsen et al, 2013;Smedskjaer et al, 2013;Striepe et al, 2013b;Aakermann et al, 2015;Rouxel and Yokoyama, 2015). It is commonly believed that the surface strengthening against contact cracking comes from the linear superposition of a compressive stress (CS) profile onto the surface of the glass (Marshall and Lawn, 1978;Lawn and Fuller, 1984).…”

Deformation and cracking behavior of glasses indented with diamond tips of various sharpness

“…Formation of the initial ring crack requires both sufficient radial tensile stress during contact and an initiation site in the form of a pre-existing flaw. The transition from normal to anomalous Vickers cracking behavior has been shown for NBO-free xCaO-xAl 2 O 3 -(100-2x)SiO 2 glasses [27]. Increases in the most highly densifiable component, SiO 2 , led to increases in the crack resistance until ring cracking occurred at >85 mol% SiO 2 .…”

“…Near the point at which dE/dT f changes sign it is also expected that the pressure and temperature coefficients of shear and bulk moduli also change sign [2]. Along the transition from normal to intermediate glass behavior, the crack resistance increased as the molar volume increased and slopes dρ/dT f and dE/dT f decreased [27].…”

“…The dependence of elastic properties on fictive temperature, pressure, and temperature may be an important indicator as to when the glass will have a high tendency toward ring cracking even under relatively sharp Vickers contact. When considering plastic flow, the structural changes along shear lines should also be considered since shear dilatation (normal glasses) or shear compaction (anomalous glasses) appear to occur and should affect the crack resistance [10,27].…”