Original scientific paper
Structural Properties of IPS Empress Ceramics in Dependence of Different Modalities of Coo
Ketij Mehulić
; School of Dental Medicine, University of Zagreb, Zagreb, Croatia
Jasenka Živko-Babić
; School of Dental Medicine, University of Zagreb, Zagreb, Croatia
Tomislav Ivaniš
; School of Dental Medicine, University of Zagreb, Zagreb, Croatia
Mirjana Kustec-Pribilović
; Privatna stomatološka ordinacija Bulićeva 8, Zagreb, Hrvatska
Hanzi Predanić-Gašparac
; School of Dental Medicine, University of Zagreb, Zagreb, Croatia
Abstract
Empress ceramic is a leucite type glass-ceramic. By a process of
tempering the total glass volume microcrystals appear at the same time as the formation of germs and increased crystals. On the basis of the hypothesis that different parameters during laboratory procedures have an effect on the micro structure of the ceramic material, the aim of this investigation was to evaluate, by means o f a light microscope, the structural changes in Empress ceramic, depending on the method of cooling, and to determine in what way different modalities o f cooling effect the value of microhardness, measured by the method according to Vickers, under a loading o f 5 N. It was established that fasta cooling of the muffle had an effect on the microstructure, reducing the share o f the crystal component. Fast cooling causes the crystals to reduce in size and visible microfractures to appear on the surface, and their interface with the crystal matrix. Values of the microhardness of the base materials for both techniques did not changes significantly depending on the speed o f the cooling, and ranged from 560 to 670 HV.
Keywords
Empress ceramic; microstructure; michohardness
Hrčak ID:
99388
URI
Publication date:
15.6.1997.
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