The effect of cesium-containing leucite additions on the thermal and mechanical properties of two leucite-based porcelains.
It has been demonstrated that a Cs(2)O-stabilized leucite porcelain was susceptible to a stress-induced phase transformation, but toughening was not observed.1 It was hypothesized that if Cs(2)O-stabilized leucite core particles were added to a cesium-free matrix porcelain, selected or designed to enhance the toughening mechanism, toughening would occur. A commercial porcelain (VP) and a synthesized leucite-based porcelain (NP) were the matrix materials. Core particles of Cs(2)O (0.0-2.0 mol%) containing synthetic leucite were mixed with the two cesium-free matrix porcelains and vacuum fired into specimens for testing. The toughness of both types of matrix-based materials was dependent upon cesium content of the added core particles with a maximum toughness reached for those containing 0.75 mol% Cs(2)O. The toughness of the 0.75 mol% specimens (1.42 MNm(-3/2) for VP based and 2.15 MNm(-3/2) for NP based) was statistically (p <.02) higher than either of the matrix materials alone or the matrix materials containing added core particles of synthetic cesium-free leucite. However, the toughest materials (0.75 mol% Cs(2)O) were not the strongest materials, most likely because of large internal flaws. The results suggested that transformation toughening was possible.
Rasmussen
Stephen T
ST
School of Dentistry, University of Michigan, Ann Arbor, Michigan 48109, USA.
McLaren
Charles I
CI
O'Brien
William J
WJ
D000538:Aluminum Silicates / Q000737:chemistry*; D001672:Biocompatible Materials / Q000737:chemistry*; D002586:Cesium / Q000737:chemistry*; D003442:Crowns; D003776:Dental Porcelain / Q000737:chemistry*; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D014961:X-Ray Diffraction
D000538:Aluminum Silicates; D001672:Biocompatible Materials; D003776:Dental Porcelain; C078519:leucite; D002586:Cesium