ABSTRACT
MICROWAVE SINTERING AND CHARACTERIZATION OF ALUMINA
AND ALUMINA MATRIX CERAMIC NANOCOMPOSITES
Kayiplar, Burcu
M.S., Department of Metallurgical and Materials Engineering
Supervisor: Assist. Prof. Dr. Arcan F. Dericioglu
April 2010, 106 pages
Efficiency of microwave heating on the sintering of ceramic materials has been
investigated in comparison to conventional processing. Monolithic alumina with or
without sintering additives such as MgO, CaO, Y2O3 were fabricated by both
conventional and microwave sintering at temperatures ranging from 1000° / C to
1600° / C with a constant soaking time of 1 hour. Based on the densification results
on monolithic alumina, nanometer-sized SiC or stabilized ZrO2 particle-dispersed
alumina matrix ceramic nanocomposites were sintered by both methods at 1300° / C
and 1500° / C for 1 hour. Sintered ceramic materials were characterized in terms of
densification, microstructural evolution, chemical composition and mechanical
properties such as hardness and indentation fracture toughness.
Microwave sintering was determined to be a remarkably effective method in the
production of Al2O3 ceramics at considerably low temperatures (& / #8804 / 1400° / C)
compared to conventional sintering in achieving enhanced relative densities
reaching to ~97% with improved microstructural characteristics and mechanical
properties. Usage of sintering additives at temperatures higher than 1400° / C was
determined to be effective in densifiying Al2O3 by both methods. Second phase
particle incorporation yielded poor densification resulting in a decrease of
hardness of the fabricated ceramic nanocomposites / however, their fracture
toughness improved considerably caused by the crack deflection at the dispersed
particles and grain boundaries reaching to ~4 MPa· / m1/2 in the case of SiC particledispersed
nanocomposites. Compared to conventional sintering, microwave
sintering is more effective in the processing of alumina and alumina matrix
nanocomposites leading to similar densification values along with improved
microstructural and mechanical characteristics at lower temperatures in shorter
soaking periods.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/3/12611854/index.pdf |
| Date | 01 April 2010 |
| Creators | Kayiplar, Burcu |
| Contributors | Dericioglu, Arcan Fehmi |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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