ISSN:
1013-9826
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Small amounts of Al2O3 were added to fine zirconia powder by different ways: powdermixing, hydrolysis of alkoxide, and homogeneous precipitation. During a constant rate heatingprocess, the Al2O3 addition slightly raised the starting temperature of densification of powdercompact, and the densification was remarkably stimulated by Al2O3 at temperatures above about1100oC. According to an isothermal analysis of densification, the densification rate was retarded byAl2O3 addition just after the start of sintering and then the densification rate increased significantlyduring sintering compared to Al2O3-free powder. These results mean that Al2O3 particles pinned theshrinkage of zirconia powder compact at the initial stage, and diffuse toward zirconia surface toenhance the sintering. The sintering mechanism was explained by the grain-boundary diffusion forthe Al2O3-free powder and the volume diffusion for Al2O3-added powder. When the Al2O3 was addedto zirconia powder by homogeneous precipitation and alkoxide methods, the densification rate wasmore stimulated compared to powder mixing method. The sintering mechanism did not change bythe way for Al2O3 addition. The Al2O3 addition by the chemical process tended to enhance the graingrowth of zirconia, while the uniform microstructure was achieved because of homogeneousaddition of Al2O3 by these chemical processes
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/55/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.352.219.pdf
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