Filtreler
Carbon nanotube-reinforced hydroxyapatite coatings on metallic implants using electrophoretic deposition

Kaya C. | Kaya F. | Cho J. | Roether J.A. | Boccaccini A.R.

Conference Object | 2009 | Key Engineering Materials412 , pp.93 - 97

Electrophoretic deposition (EPD) has been demonstrated to be a convenient processing technique to fabricate composite ceramic coatings containing ordered arrays of carbon nanotubes. In this investigation, EPD was used to coat Ti6Al4V medical implants with hydroxyapatite (HA) layers reinforced with surface functionalized multi-walled carbon nanotubes (MWCNTs). The functionalization of MWCNTs by treating them with an acid mixture was successfully achieved in order to create functional groups on the MWCNT surfaces enabling them to be homogeneously dispersed in water. The surface treatment was also used to induce the adsorption of HA na . . .noparticles on MWCNT surfaces. Some critical issues, such as microcracking and peeling of HA layers after EPD, were effectively solved by the use of MWCNTs Daha fazlası Daha az

Microstructural and mechanical properties of nano-yttria-oxide doped hydroxyapatite composites

Gunduz O. | Yetmez M. | Ekren N. | Kilic O. | Ben-Nissan B. | Oktar F.N.

Conference Object | 2018 | Materials Science Forum923 MSF , pp.89 - 92

Nowadays hydroxyapatite (HA) bioceramics are very important because increasing traffic accidents and ageing of the population. They can be produced from synthetic or natural sources with different production methods. The biggest negative issue of HA is being very brittle and unstable under pressure. Various materials are added for restoring these weaknesses, but there is not so much studies adding nano-ingredients for restoring the mechanical properties of HA. In this study, 5-10% nano-yittria-oxide is added to bovine derived HA (BHA) and to commercial synthetic (CSHA) as a control group. Physical and mechanical properties are exami . . .ned. Results show that adding of nano-ingredients are really helping to mechanical properties of HA. © 2018 Trans Tech Publications, Switzerland Daha fazlası Daha az

A new natural biomaterial: Sheep dentine derived hydroxyapatite

Akyurt N. | Yetmez M. | Karacayli U. | Gunduz O. | Agathopoulos S. | Gokce H. | ÖveÇoglu M.L.

Conference Object | 2012 | Key Engineering Materials493-494 , pp.281 - 286

Hydroxyapatite (HA) is a particularly attractive material for bone and tooth implants since it does not only closely resemble human tooth and bone mineral but it has also biologically proven to be compatible with these tissues. The applications of pure HA are restricted to non load bearing implants due to the poor mechanical properties of HA. Biomaterials of synthetic HA are highly reliable but the synthesis of HA is often complicate and expensive. Bioceramics of naturally derived biological apatites are more economic. Aim of the present work is to introduce sheep teeth dentine HA material as an alternative source of bioactive bioma . . .terials for grafting purposes. The work was started with such a way that extracted sheep teeth were cleaned. The teeth were calcinated at 850°C in air. It was seen that enamel matter was easily separated from dentine after calcination. The collected dentine parts were crushed and ball milled. The powder was pressed between hardened steel dies to produce samples suitable for compression and microhardness tests. The obtained powder compacts were sintered at different temperatures, specifically 1000, 1100, 1200, and 1300°C in air. Results of microhardness and compression strength (along with the statistical analysis of these results) as well as those of SEM and XRD analyses are presented. In the literature, there is very little information about the mechanical properties of dentine and enamel matter derived from sheep, bovine and human. The highest compression strength value in the present study was measured around 146 MPa (from human dentine derived HA the highest value was almost 60 MPa after sintering at 1300°C). The best microhardness in the present study was found as nearly 125 HV. The results of this study showed that the HA material produced from sheep tooth dentine can be qualified as a promising source of HA needed to produce bioactive ceramics. © (2012) Trans Tech Publications, Switzerland Daha fazlası Daha az

Characterization of bovine dentine derived hydroxyapatite (BDHA) structures

Akyurt N. | Oktar F.N. | Karacayli U. | Yetmez M. | Pazarlioglu S. | Salman S.

Conference Object | 2011 | Proceedings of the Euro International Powder Metallurgy Congress and Exhibition, Euro PM 20112 , pp.281 - 286

Hydroxyapatite (HA, Ca10(PO4)6(OH)2), the main mineral component of bones and teeth, is among the leading biomaterials being an ideal material for grafting purposes in orthopedic and dental applications. The HA bioceramics can be naturally derived or synthetically produced. The synthetic HAs are reliable, but their production is usually complicate and expensive. To develop natural bioceramics seems to be a more economic way. The aim of this study was to develop a novel natural HA from bovine tooth dentine material. For this purpose, bovine teeth were calcined and the enamel was separated from dentine. Dentine parts were ball milled . . .and pressed to green compacts. Those compacts were sintered at 1000, 1100, 1200 and 1300°C. Compression strength, microhardness, and density measurements along with SEM and X-ray diffraction analyses were conducted. From those results (e.g. microhardness was 346HV for sintering at 1300°C) it was seen that bovine dentine derived HA (BDHA) is an interesting and reliable source of HA for producing biomaterials Daha fazlası Daha az

Hydroxyapatite nano-barium-strontium-titaniumoxide composites

Demirkol N. | Kayali E.S. | Yetmez M. | Oktar F.N. | Agathopoulos S.

Conference Object | 2011 | Key Engineering Materials484 , pp.204 - 209

The aim of this study is to produce and to investigate the mechanical and microstructural properties of composite materials made of hydroxyapatite, obtained from natural bovine bone and nano barium strontium titanium oxide (5 and 10 wt%). Compositions were mechanical alloyed and compacted to pellets. The samples were subjected to sintering at different temperatures between 1000°C and 1300°C. Compression strength, Vickers microhardness as well as density were measured. SEM and X-ray diffraction studies were also conducted. With increasing sintering temperature, microhardness, compression strength and density of composites increased. . . .With increasing addition of nano barium strontium titanium oxide (BST) to bovine hydroxyapatite (BHA), microhardness values of composites decreased at all sintering temperatures, but compression strength and density values of composites showed different tendency. Compression strengths of BHA-composites at low sintering temperatures were nearly the same, but their compression strengths at high sintering temperatures decreased with increasing nano BST addition. The best mechanical properties were obtained at 1300°C sintering temperature with BHA-5wt% nano BST. Microhardness and compression strengths values of these nano-oxide composites are generally higher than that BHA-composites produced by traditional methods. Adding of nano-oxides to BHA could be a valuable method to produce rigid and high load carrying ability when compared with BHA-composites produced by conventional methods. Nano-HA and nano-oxides composites could be even better. Those nano-nano studies are still in progress. © (2011) Trans Tech Publications, Switzerland Daha fazlası Daha az

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