Papers by Keyword: Alumina Ceramic

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Authors: M. Hamadouche, A. Meunier, D.C. Greenspan, C. Blanchat, J.P. Zhong, G.P. La Torre, Laurent Sedel
Authors: Qing Bo Tian, Jin Shan Dai, Li Na Xu, Xiu Hui Wang
Abstract: The sintering of alumina ceramics with high-purity has gained much attention due to their wide range applications. The improved sinteirng methods, such as the spark plasma sintering, super-high pressure sintering, two-step sintering, and so on, have advantages on the decreasing the sinteirng temperature or inhibiting the grain coarsening, compared with the conventional sintering.
Authors: Yasuhito Tanaka, Yoshinori Takakura, K. Kadono, Akira Taniguchi, K. Hayashi, Jin Iida, Koh Ichi Sugimoto, Yasuaki Tohma, Hajime Ohgushi
Authors: M. Hamadouche, A. Meunier, D.C. Greenspan, C. Blanchat, J.P. Zhong, G.P. La Torre, Laurent Sedel
Authors: Clifford W. Colwell, J.A. D'Antonio, W.N. Capello, M.E. Hardwick
Abstract: Alumina ceramic is an excellent material for biologic implantation. Decreased particulate wear debris should increase implant longevity. The purpose of this study is to examine clinical and radiological results of ceramic-on-ceramic hip implants compared to cobalt chrome on polyethylene. Four cementless systems were compared, three alumina-on-alumina bearing systems: System I, porous coated cup; System II, hydroxyapatite-coated cup; Trident system, hydroxyapatite-coated cup with metal sleeve backing on ceramic cup liner; and System III (control), porous-coated cup with polyethylene and cobalt chromium bearing system. Patients were randomized to receive System I, II, or III. Trident patients were not randomized. Examinations are performed at 6 months, 1 year and yearly thereafter including x-rays, clinical exam and Harris Hip Score (HHS). Minimum 24-month followup was performed in 562 ceramic hips and 154 control hips. Age, height, weight, gender and diagnosis were similar in all groups. HHS was rated good/excellent by 95 percent of ceramic hips and 97 percent of control hips. Radiographic results demonstrated radiolucency in Femoral Gruen Zone 1 in 3.8 percent (18/474) of ceramic hips and in 8 percent (10/128) of control hips. Unstable acetabular components were reported in none of ceramic hips and in 3.2 percent (5/154) of control hips. Revision was performed in 7 (1.2 percent) ceramic hips, none due to failure of ceramic materials, and in 9 (5.8 percent) control hips. Alumina ceramic materials show promise, but continued evaluation of long-term clinical results is needed.
Authors: Dagmar Galusková, Pavol Šajgalík, Dušan Galusek, Miroslav Hnatko
Abstract: Two alumina based ceramics with 99.99 % and 95 % of Al2O3 were evaluated after dissolution in an aqueous solution containing 0.5 mol/l NaCl at temperatures of 150 and 200 °C. The weight loss of liquid phase sintered alumina was mainly attributed to congruent dissolution of SiO2 and CaO from grain-boundary amorphous film, which is accelerated at higher temperature, accompanied by precipitation of silicaceous phases from oversaturated solution at 200 °C. Pure polycrystalline alumina corroded by loss of alumina grains, which do not dissolve in the corrosion media.
Authors: Magdalena Szutkowska, Marek Boniecki
Abstract: The relationship of KR versus crack length c (R curve) for Al2O3-30wt.% Ti(C,N).and for comparison alumina ceramics has been examined. The R-curve has been evaluated using pronounced long-crack formed during the three point bending (3PB) of the double edge notched beam. A combination of in situ microscopic crack growth observation and mechanical testing enabled measurement of crack growth resistance curves. The special device consisting of light microscope coupled with CCD camera, was fitted to Zwick 1446 testing machine. These observations reveal the existence of flat R-curve for Al2O3-30wt.% Ti(CN) and increasing R-curve for pure alumina. A study of slow-crack-growth (SCG) in tested materials was carried. The load-relaxation technique was used for observation at slow-crack-growth. The crack length was evaluated by linear-elastic analysis from the compliance of single-edge-notched specimen in three-point bending test. Parameters of stable crack growth n and logA, work-of fracture (WOF), stress intensity factor at the moment of crack initiation KI0 and maximum values of stress intensity factor KImax were determined. Mechanism of grain bridging responsible for occurrence of R-curve was observed by SEM and TEM.
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