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

1995; Wiley; Volume: 78; Issue: 2 Linguagem: Inglês

10.1111/j.1151-2916.1995.tb08831.x

1551-2916

Hockin H.K. Xu, Said Jahanmir,

Advanced ceramic materials synthesis

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.