Title: Microstructure and indentation fracture toughness of mica glass ceramics

Authors: Abdullah Ozturk

Addresses: Metallurgical and Materials Engineering Department, Middle East Technical University, 06531 Ankara, Turkey

Abstract: Mica glass ceramics were produced through controlled crystallisation of a glass in the SiO₂-Al₂O₃-CaO-MgO-K₂O-MgF system. TiO₂, P₂O₅ and ZrO₂ were added individually as nucleating agents in the amount of 0.5 or 1.0 wt% of the glass. Crystalline phases were identified by X-ray diffraction. The effects of small amounts of various nucleating agents on the microstructure were determined by scanning electron microscopy. Microstructural analyses were supplemented with measurements of the Vickers microhardness and indentation fracture toughness. The amount and kind of nucleating agent did not change the number of crystalline phases present but had an influence on the shape and size of the crystals, and hence on the indentation fracture toughness of the mica glass ceramics. The values for the indentation fracture toughness for the mica glass ceramics containing 0.5 wt% of TiO₂, P₂O₅ and ZrO₂ were 1.69±0.09 MPa.m^1/2, 1.74 ± 0.10 MPa.m^1/2 and 1.77 ± 0.12 MPa.m^1/2, respectively.

Keywords: microstructure; microhardness; indentation; fracture toughness; mica glass ceramics.

DOI: 10.1504/IJMMP.2008.022614

International Journal of Microstructure and Materials Properties, 2008 Vol.3 No.6, pp.780 - 790

Published online: 19 Jan 2009 *

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