Fracture of Ceramics with Different Conical Indenters: Edge Chipping.

Mechanical tests for evaluating the fracture resistance of ceramics on chipping rectangular specimen edges were first performed with conical diamond indenters of 11-800 μm tip radii. In the experiments elastic silicon-nitride SiN ceramics and inelastic zirconia TS ceramics, displaying a phase transition on fracture, were used, soda lime glass served as the object for comparison. The fracture resistance of those materials was shown to increase similarly when the above indenters are employed. Chip scars formed on the specimen edges of SiN ceramics do not actually differ from those observed in glass tests (pseudoconical, nail-like, arbitrary). With an increase in the tip radius, the first ones grow in number. It does not take place in the tests of TS ceramics. Comparative fracture resistance estimates obtained with the edge chipping method using different fracturing tools were established to be invalid. [ABSTRACT FROM AUTHOR]