Scratching and Grinding of a Machinable Glass-Ceramic with Weak Interfaces and Rising T-Curve

H. H. K. Xu and S. Jahanmir, “Scratching and Grinding of a Machinable Glass-Ceramic with Weak Interfaces and Rising T-Curve,” J. Am. Ceram. Soc., 78 (1995) 497-500.

The scratching and grinding response of a machinable mica-containing glass-ceramic is examined relative to the base glass. The influence of weak interfaces and a rising toughness curve (T-curve) on machinability and damage modes is investigated. A profound manifestation of these characteristics is a change in the nature of subsurface damage from macroscopic fracture in the base glass to distributed microfracture in the glass-ceramic. As a result, the mechanism of material removal changes from extension of macrocracks in the base glass to microfracture and dis-lodgement of the mica grains in the glass-ceramic. High removal rates in scratching compare with low forces in grinding of the glass-ceramic. The removal rates and the grinding forces are found to correlate with the short-crack toughness instead of the conventional long-crack toughness.

Abrasive machining of ceramics possessing weak grain boundaries and interfaces and associated rising T- curve behavior is discussed in light of these results.


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