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The relationship between microstructure and fracture toughness of zirconia toughened alumina (ZTA) added with MgO and CeO2

Rejab, Nik Akmar and Ahmad Azhar, Ahmad Zahirani and Ratnam, Mani Maran and Ahmad, Zainal Arifin (2013) The relationship between microstructure and fracture toughness of zirconia toughened alumina (ZTA) added with MgO and CeO2. International Journal of Refractory Metals and Hard Materials, 41. pp. 522-530. ISSN 0263-4368

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Abstract

The aim of this research is to investigate the mode of crack propagation in zirconia toughened alumina (ZTA) added with MgO and CeO2, respectively. The mode of crack refers to the toughening mechanism of the materials. Different ZTA compositions containing MgO and CeO2 as sintering additives were prepared using pressureless sintering at 1600 °C. Each sample was subjected to Vickers indentation with 294 N load and the cracks that propagated were observed with SEM. The ZTA with an addition of 0.7 wt.% MgO showed a crack deflection with a fracture toughness value of 6.19 ± 0.26 MPa · √m. On the other hand, the ZTA with CeO2 addition of 0.5 to 7 wt.% showed both crack bridging and deflection, and produced 5.78 ± 0.16 MPa · √m to 6.59 ± 0.23 MPa · √m fracture toughness values, respectively. The fracture toughness of the ZTA–MgO–CeO2 compositions is higher due to crack bridging and crack deflection. The toughening mechanisms of crack deflection and bridging hinder crack propagation since more energy is required to make the crack propagate. However, the formation of CeAl11O18 phase was observed; this consequently decreases the hardness and fracture toughness of the ZTA–MgO–CeO2 compositions.

Item Type: Article (Journal)
Additional Information: 6954/33035
Uncontrolled Keywords: Microstructure; Vickers hardness; Fracture toughness; Palmqvist crack
Subjects: T Technology > TA Engineering (General). Civil engineering (General) > TA401 Materials of engineering and construction
Kulliyyahs/Centres/Divisions/Institutes: Kulliyyah of Engineering > Department of Manufacturing and Materials Engineering
Depositing User: Dr Ahmad Zahirani Ahmad Azhar
Date Deposited: 04 Dec 2013 09:33
Last Modified: 22 Apr 2014 16:12
URI: http://irep.iium.edu.my/id/eprint/33035

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