Home About us Contact
|
Home About us Contact | ||
|
|
||
Zirconia Ceramics (zirconia + ceramics)
Selected AbstractsImprovement in the Specific Strength by Arranging Closed Pores in Fully Densified Zirconia Ceramics,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2009Akira Kishimoto Superplastic-foamed porous ceramics containing numerous closed pores were fabricated. The bending strength of the fabricated ceramics with the smallest pores was close to half that of fully dense ones, even with a porosity of 27%. The smaller pores were introduced selectively between top and bottom surfaces. The resultant dense/porous/dense layered ceramics had a specific mechanical strength greater than that of monolithic dense ceramics. [source] Biomimetic Preparation and Characterization of Bioactive Coatings on Alumina and Zirconia CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2010Irena Pribo For the preparation of bioactive coatings on alumina and zirconia ceramic surfaces a fast biomimetic method using a supersaturated solution containing Na+, Ca2+, Cl,, HCO3,, and PO43, ions was used. The coatings were analysed with the use of an X-ray diffraction spectrometer and a transmission electron microscope equipped with an energy-dispersive spectroscopy detector. After the precipitation both coatings were composed of poorly crystallized, nanosized, plate-like particles with the octacalcium phosphate (OCP) crystal structure. The adhesion of the coatings was improved by a heat treatment at 1050°C for 1 h. During this heat treatment the calcium phosphate layer, deposited from a supersaturated solution onto the surface of the substrates, was sintered to form a dense coating. At the same time the OCP crystal structure was transformed into that of hydroxyl apatite, the coating's crystallinity was increased, and the particles grew isotropically up to 300 nm in size. The bioactivity of the coated ceramic was confirmed before and after the heat treatment using a simple simulated body fluid test. [source] Bone Tissue Responses to Surface-Modified Zirconia Implants: A Histomorphometric and Removal Torque Study in the RabbitCLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 2005Lars Sennerby DDS ABSTRACT Background: Zirconia ceramics are biocompatible and have mechanical properties that make them suitable as materials for dental implants. Little is known about how surface modification influences the stability and bone tissue response to zirconia implants. Purpose: The objective of the investigation was to histologically and biomechanically evaluate the bone tissue response to zirconia implants with two different surface modifications in comparison with machined, nonmodified zirconia implants and oxidized titanium implants. Materials and Methods: Threaded zirconia implants with a diameter of 3.75 mm with either a machined surface (Zr-Ctr) or one of two surface modifications (Zr-A and Zr-B) were manufactured. Oxidized titanium (Ti-Ox) implants 3.75 mm in diameter were also used. The implants were characterized with regard to surface topography using an interferometer. Twelve rabbits received 96 implants using a rotational scheme, two in each tibia and two in each femur. The implants in six rabbits were subjected to removal torque (RTQ) tests after a healing period of 6 weeks. The implants in the remaining six animals were removed en bloc for light microscopic analysis. Back-scatter scanning electron microscopic (BS-SEM) analyses were used to evaluate the state of the bone-implant interface at the modified zirconia implants after RTQ testing. Results: The Ti-Ox and Zr-A implants showed the highest surface roughness, followed by the Zr-B implants and, finally, the Zr-Ctr implants. The nonmodified ZrO2 implants showed statistically significant lower RTQs than all other implants. No significant differences in bone-implant contact or bone area filling the threads were observed. BS-SEM showed intact surface layers of the surface-modified implants after RTQ testing and revealed fracture of the interface bone rather than a separation. Conclusion: The present study showed a strong bone tissue response to surface-modified zirconia implants after 6 weeks of healing in rabbit bone. The modified zirconia implants showed a resistance to torque forces similar to that of oxidized implants and a four- to fivefold increase compared with machined zirconia implants. The findings suggest that surface-modified zirconia implants can reach firm stability in bone. [source] Application of Hertzian Tests to Measure Stress,Strain Characteristics of Ceramics at Elevated TemperaturesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2007Estíbaliz Sánchez-González A new method for evaluating the elastic,plastic properties of ceramics from room temperature up to the onset of creep based on Hertzian indentation testing is proposed. Indentation stress,strain curves are compiled for representative alumina and zirconia ceramics at prescribed temperatures. Deconvolution of the indentation stress,strain curves for each material provides a measure of Young's modulus, yield stress, and work-hardening coefficient as a function of temperature, enabling construction of true stress,strain curves. The stress,strain curves flatten out with increasing temperature, in accordance with an expected increased plastic response at elevated temperatures. [source] T. Gunji, H. Yamamoto, T. Hanaoka, K. Bandoh-Kitmura and Y. Abe, ,Preparation of polyzirconoxane from zirconium octahydrate and ethylene glycol as a precursor for zirconia ceramics'.APPLIED ORGANOMETALLIC CHEMISTRY, Issue 4 2001Applied Organometallic Chemistry 2000; 14(2):11 The original article to which this Erratum refers was published in Applied Organometallic Chemistry 2000; 14(2):119,126. In the Table of Contents for the February 2000 issue of Applied Organometallic Chemistry, Volume 14 Number 2, the authors of the paper appearing on page 119, ,Preparation of polyzirconoxane from zirconium octahydrate and ethylene glycol as a precursor for zirconia ceramics', should have been listed as T. Gunji, H. Yamamoto, T. Hanaoka, K. Bandoh-Kitmura and Y. Abe. [source] | ||||||||||