Zirconia/alumina nanocomposites

Ceria-Stabilized Zirconia/Alumina Nanocomposite Suitable for Electrophoretic Deposition... 

CERIA-STABILIZED ZIRCONIA/ALUMINA NANOCOMPOSITE SUITABLE FOR ELECTROPHORETIC DEPOSITION IN THE FABRICATION OF DENTAL RESTORATIONS... 

Nawa, M., Yamada, K. and Pezzotti, G. (2008) Miaoscopic mechanisms behind the toughening behavior of ceria stabilized tetragonal zirconia/alumina nanocomposite for biomedical applications. Key Engineering Materials, 361-363, 813-16. 

From Conventional to Fast Sintering of Zirconia Toughened Alumina Nanocomposites... 

Biamino, S., Fino, P., Pavese, M. and Badini, C. (2005) Alumina-zirconia-yttria nanocomposites prepared by solution combustion synthesis. Ceramics International, 32, 509-13. 

Bartolome, ).F., De Aza, A.H., Martin, A., Pastor, ).Y., Uorca,)., Tonecillas, R. and Brunoz, G. (2007) Alumina/ zirconia micro/nanocomposites a new material for biomedical applications with superior sliding wear resistance. Journal of the American Ceramic Society, 90, 3177-84. 

The use of different metal aUcoxides to form the initial sol results in mixed aerogels (binary solid solutions of silica, titania, alumina, zirconia, vanadia, mtenia, etc.) that cannot be considered as nanocomposited. This field has also been largely explored for catalytic applications [10]. 

Alumina-based composites These comprise especially zirconia-toughened alumina (ZTA), and alumina-based nanocomposites with non-oxide second phases such as SiCorTiC. However, thelattertwo, in particular, are b ond the scopeofthis chapter. 

The measured V — Ki diagrams of alumina and the composites prepared with the colloidal route and different volume fraction of unstabilized zirconia are plotted in Fig.l4 AI2O3, A7.5Z, AIOZ and A15Z correspond to nanocomposites with 0, 7.5, 10 and 15 vol % ZrOi respectively and A7.5Z-2Y is a composite with 7.5 vol % Zr02, stabilized by 2 mol % Y2O3. Subcritical crack growth laws were measured using the double torsion technique and the relaxation method. 

Another noteworthy effort at nanocomposite fabrication applied ceramic nanoparticles to a ceramic material to enhance osteoconductivity and mechanical performance. Nawa et al. [49] developed a ceria-stabiHzed tetragonal zirconia polycrystal (Ce-TZP) ceramic and incorporated alumina (AI2O3) nanocrystals into it via wet chemistry methods for load-bearing bone applications. Further studies of this material investigated its ability to induce apatite formation [50], in vivo biocompatibility, and resistance to wear [10] with favorable results. 

Affatato, S., Torredllas, R., Taddei, P., Rocchi, M., Fagnano, C., Ciapetti, G. and Toni, A. (2005) Advanced nanocomposite materials for orthopaedic applications. 1. A long-term in vitro wear study of zirconia-toughened alumina. Journal of Biomedical Materials Research, Part B, 78B, 76-82. 

An end face apparatus (Fig. 1) was used to measure wear rate between nominally flat surfaces with minimum lubrication effects. The upper disc is made of alumina, zirconia or alumina/zirconia nanocomposite cerantics. The mating disc of medical... 

A pin on flat apparatus (Fig. 2) was used to measure wear rate under concentrated contact and reciprocating motion. The square plate is made of alumina, zirconia or alumina/zirconia nanocomposite ceramics. The pin of medical grade alumina had an end face with 10 mm spherical radius. The lower plate oscillates while the vertical load is applied to the pin by dead weights. Friction force is measured with strain gauges attached to the double leaf springs. Applied load is 30 N, oscillation frequency is 2 c/s, stroke is 10 mm and mean sliding velocity is hence 40 mm/s. Wear test was performed in 30 vol.% bovine serum solution kept at 37 °C. Wear volume of the pin was calculated from the area of the wear surface while the wear volume of the disc was calculated by the weight loss. 

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