Applicabilities of Equations of σm=ΨK_ICS_mf^1/2 and σ_d^-1=σ₀^-1+Ka^1/2 to Soda Lime Glass

抄録

We have already clarified that our derived equations of σm=ΨK_ICS_mf^1/2 as well as σ_d^-1=σ_o^-1+Ka^1/2 are applicable to various hard or brittle sintered materials such as WC-Co hardmetal and Si₃N₄ ceramics (σ_m: flexural strength, Ψ: shape factor, K_IC: fracture toughness, S_mf: total macroscopic fracture surface area of fragments, σ_d: external stress which operated on the fracture origin, σ_o: intrinsic or attainable fracture strength, K: material factor, a: half length of fracture origin). In this study, we investigated whether these two equations are applicable to soda lime glass which is non-crystalline and has extremely low K_IC. It was found that both equations are also applicable to soda lime glass, when S_mf+S_c is used in the application of the former equation, instead of S_mf (S_c: the total macroscopic fracture surface area of internally stopped cracks). The fracture started from a visible microstructural defect with sizes of 10-30μm even for polished test pieces with σ_m values of 180-78 MPa. A correction was made in the derivation process of the former equation: the equation itself, however, was not changed.