Edge Fracture Resistance of Glasses: Different Conical Indenters and the Fracture Initiation Barrier

摘要

An increased fracture initiation barrier of brittle materials is examined by the example of test results for flat glass. The fracture resistance of this glass on the rectangular specimen edge chipping with conical diamond indenters of different tip radii (11-800 mu m) was evaluated. Optical glasses (quartz and light crown) were used for comparison. A significant change in glass behavior on the edge chipping of their specimens is observed only with the indenter of an 11-mu m tip radius. In this case, the crack resistance of glasses is equal to that measured in Vickers experiments. Any basic differences in the fracture behavior of glasses with the indenters of tip radii of 100 and more micrometers were not revealed. The prescratching of the glass specimen surface near its edge before its chipping was noticed to exert negative effect on crack resistance estimates since its characteristic fracture initiation barrier is damaged.