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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Evaluation of the micro-hardness and fracture toughness of amorphous and partially crystallized 3CaO center dot P2O5-SiO2-MgO bioglasses

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Author(s):
Daguano, Juliana K. M. F. [1] ; Suzuki, Paulo A. [1] ; Strecker, Kurt [2] ; Fernandes, Maria H. F. V. [3] ; Santos, Claudinei [1, 4]
Total Authors: 5
Affiliation:
[1] Univ Sao Paulo, Escola Engn Lorena, BR-12600000 Lorena, SP - Brazil
[2] Univ Fed Sao Joao del Rei UFSJ CENEN, BR-36307352 Sj Del Rei, MG - Brazil
[3] Univ Aveiro, Dept Ceram & Glass Engn, P-3810193 Aveiro - Portugal
[4] Univ Estado Rio de Janeiro, Fac Tecnol Resende, UFRJ FAT, BR-27537000 Resende, RJ - Brazil
Total Affiliations: 4
Document type: Journal article
Source: MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING; v. 533, p. 26-32, JAN 30 2012.
Web of Science Citations: 9
Abstract

In this work, the effect of the indentation load on the results of hardness and fracture toughness, determined by Vickers micro-hardness measurements, of some glasses and glass-ceramics has been investigated. Furthermore, in order to verify the effect of crystallinity on the results, glasses of composition 52.75 wt.% 3CaO center dot P2O5, 30 wt.% SiO2 and 17.25 wt.% MgO were fused at 1600 degrees C for 4 h and annealed at 700 degrees C for 2h, and further heat-treated at 700, 775, 800 and 900 degrees C for 4h. The obtained materials were analyzed by high resolution X-ray diffraction, HRXRD, to determine the crystallization degree in function of the heat-treatment temperature. The hardness of the different specimens was determined by Vickers' micro-hardness measurements under various loads. It has been observed that with increasing crystallization of the materials their hardness increased. Furthermore, it has been possible to verify the so-called indentation size effect (ISE), i.e. hardness decreases as the indentation depth, under higher loads, increases. This effect has been more pronounced in the glass-ceramic samples. Fracture toughness has been determined by the crack length induced by the Vickers indentations and relating them to the applied loads. Glass materials presented a fracture pattern with characteristics of cleavage, forming cracks of the half-penny shaped type, while the glass-ceramic materials exhibited crack bridging effects and Palmqvist type cracks. (C) 2011 Elsevier B.V. All rights reserved. (AU)