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1734978 
Book/Book Chapter 
FROM CONVENTIONAL TO FAST SINTERING OF ZIRCONIA TOUGHENED ALUMINA NANOCOMPOSITES 
Volceanov, E; Aldica, GV; Volceanov, A; Constantinescu, D; Motoc, S 
2010 
Ceramic Engineering and Science Proceedings 
30 
2 
91-102 
WOS:000281694100008 
The aims of this study are to clarify the effect of different fast sintering techniques on densification behavior, microstructure and mechanical properties of a ZTA type composite obtained with 15 % vol. (Ca-Mg)-ZrO(2) nanosized zirconia dispersed in 85% vol. Al(2)O(3) matrix. Three kind of heat consolidation techniques were applied respectively on coprecipitated nanosized alumina-zirconia powders by: 1) conventional sintering; 2) microwaves field sintering at 2.45 GHz and 3) external pulsed electrical field (Spark Plasma Sintering), making possible very high heating rates. Microwave sintering of ceramics can offer certain advantages over conventional firing methods, including fast firing times and improved properties. Heat generated by the interaction of microwaves with the ceramic material results in volumetric heating of the ceramic, thus high heating rates is possible. On the other hand, a newly developed rapid sintering method, the Spark Plasma Sintering (SPS) which involves the application of electrical field and an external pressure is currently used to consolidate ceramic, metal and composite powders. SPSed high density zirconia toughened alumina (ZTA) ceramics show excellent mechanical strengths. Microstructural coarsening within ZTA is found to produce a fracture toughness increment, mainly associated with the effect of zirconia particles phase transformability. The obtained mechanical properties and grain growth kinetics are discussed in terms of microstructural features. The effects of heating technique on the far infrared and Raman spectra were investigated. Additional bands development was observed on spectra as the crystal symmetry is lowered, and certain of these bands are highly sensitive to strain-induced distortions of the crystal lattice.