14th Nordic-Baltic Conference on Biomedical Engineering and Medical Physics
14th Nordic – Baltic Conference on Biomedical Engineering and Medical Physics NBC 2008 brought together scientists not only from the Nordic – Baltic region, but from the entire world. This volume presents the Proceedings of this international co
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INTRODUCTION Silicon-based ceramic materials are either currently being used or under active consideration for use in a wide variety of applications in different industries. These materials have high strength, good oxidation and corrosion resistance, high thermal conductivity and good thermal shock resistance [1]. Silicon carbide is a commonly used ceramic material with attractive properties such as high strength, stiffness, good wear and corrosion resistance, etc., some of which are characteristic of typical covalently bonded materials. A number of manufacturing approaches have been used to fabricate these materials including hot pressing/hot isostatic pressing, sintering, reaction bonding/reaction forming, polymer pyrolysis, and chemical vapor deposition. There has been a great deal of interest in utilizing biomimetic approaches to fabricate a wide variety of silicon-based materials [2]. Up to now, several technologies have been developed for obtaining porous silicon carbide (SiC) ceramic materials from wood precursors and some of them are as follows: reactive Si vapor infiltration and reactive infiltration with Si-containing melts. Impregnation with silicon dioxide (SiO2) nanoparticles containing sol, with metal organic precursors and with sol-gel derived SiO2 sol solution also has been used to derive SiC ceramic materials [3-13]. As a result of carbothermal reactions, single-phase SiC ceramics with a relatively high porosity is commonly obtained.
Recently, biomorphic SiC coated with bioactive glass has been proposed as an alternative to titanium and titanium alloy devices due to its low density, bio-inertness, interconnected porosity and improved mechanical properties [14]. Also a study of deposition of hydroxyapatite thin films on biomorphic SiC is done in past years [15]. In this paper microstructure of several wooden breeds was investigated and discussed as prospective biomorphic SiC ceramics. To obtain biomorphic ceramics pine tree was used. Such biomorphic SiC ceramics in future can become important base for biomaterial purposes. II. EXPERIMENTAL PROCEDURE A. Materials and methods For microstructure investigations of different wooden breeds, following softwood: spruce and pine trees and hardwood: apple, alder, aspen, birch, elm, maple, lime, ash, oak, plum and mahogany trees were used. Also woody evergreen plant: bamboo was investigated. Samples were pyrolysed in oxygen free atmosphere at 500oC for easier sample preparation for structure investigations with scanning electron microscope (SEM). Biomorphic SiC ceramics were obtained from pine tree wood shaped in dimensions of 20 x 20 x 5 mm (axial) and dried at 105 oC for 24 h. SiO2 sol was prepared using TEOS - tetraethyl orthosilicate (Aldrich, Ref.: 131903), distilled water, 36% hydrochloric acid and ethanol at a suitable molar ratio to obtain the concentration of SiO2 sol equal to § 15 % by weight. Wood samples were placed in a self-made impregnation vessel, evacuated for 5 min up to a 520 mbar vacuum, then showered with SiO2 sol and delayed for 5 min bef
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