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Fabrication and Characteristics of Zirconia-Alumina Composites with Bilayer Structure

Published online by Cambridge University Press:  15 March 2011

Sung-Jae Je
Affiliation:
Department of Ceramics Science and Engineering, Changwon National University Changwon, Kyungnam 641-773, South Korea
Myung-Won Lee
Affiliation:
Department of Ceramics Science and Engineering, Changwon National University Changwon, Kyungnam 641-773, South Korea
Jae-Ean Lee
Affiliation:
Department of Ceramics Science and Engineering, Changwon National University Changwon, Kyungnam 641-773, South Korea
Yeon-Gil Jung
Affiliation:
Department of Ceramics Science and Engineering, Changwon National University Changwon, Kyungnam 641-773, South Korea
Dong-Soo Park
Affiliation:
Ceramic Materials Group, Korea Institute of machinery and Materials, Changwon, Kyungnam 641-010, South Korea
Ungyu Paik
Affiliation:
Department of Ceramic and Engineering, Hanyang University, Seoul 133-791, South Korea
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Abstract

Bilayer structures consisting of ZrO2-3mol% Y2O3(TZ-3Y) and zirconia-alumina composites as inner (substrate) and outer (coating) layers, respectively, are fabricated using gel-casting for the inner layer and dip-coating for the outer layer in aqueous system. The relatively tough TZ-3Y is used as the inner layer for damage absorption due to its mechanical properties. The mixture ratio of alumina/zirconia slips for dip-coating is 1:9, 2:8, and 3:7 as mole ratio. The processing additives for gel casting, such as dispersant, monomer, dimer, and initiator, are adjusted and optimized by measuring viscosity. From which the solid loading of starting material (TZ-3Y) is determined. The optimum amount of dispersant (D-3019; anionic dispersant agent) for TZ-3Y is 0.7 wt%. The slip pH affects the electric double layer in sols, which causes the different rheological behaviors and solid loadings. The castable solid loading of TZ-3Y is 37 vol%, showing a pseudoplastic rheological behavior. The effect of slip type (different mixture ratio) on sintered body is investigated through hardness (Vickers indentation), microstructure (SEM), and strength (4-point bending tests). Strength of sintered bodies after dip-coating into the slips is higher than that before dip-coating, but hardness is not much different among cases. The effects of thickness in the outer layer on damage resistance and mechanical properties of the bilayer structures are discussed extensively.

Type
Research Article
Copyright
Copyright © Materials Research Society 2004

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