An investigation of co-fired varistor-ferrite materials

Rafferty, Aran and Gun'ko, Yurii and Raghavendra, Ramesh (2004) An investigation of co-fired varistor-ferrite materials. Journal of the European Ceramic Society, 24 (7). pp. 2005-2013. ISSN 1873-619X

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The purpose of this work was to co-fire crack-free varistor-ferrite ceramic multilayers fabricated via a dry pressing route. Multilayers were sintered using a standard industrial grade varistor sintering regime. Sinter shrinkages of both varistor and ferrite materials were measured using dilatometry and showed that the varistor shrunk significantly more than the ferrite material. X-ray diffraction analysis indicated that no significant phase changes occurred in the materials under investigation as a result of the sintering process. Scanning electron microscopy observations of the dry-pressed co-fired varistor-ferrite revealed vertical cracking in the ferrite due to thermal expansion mismatch between the materials. By pressing a mixed composition interlayer in the ratio 50:50, between the varistor and ferrite materials, a crack-free multilayer structure could be obtained. Energy dispersive X-ray analysis of the co-fired ferrite and varistor confirmed diffusion of Fe and Ni components from the ferrite into the varistor material. The degree of diffusion was reduced by using 50:50 ratio mixed composition interlayers.

Item Type: Article
Departments or Groups: South East Applied Materials Research Centre
Divisions: School of Engineering
Depositing User: Ramesh Raghavendra
Date Deposited: 10 Mar 2014 11:21
Last Modified: 22 Aug 2016 10:27

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