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清华论坛第100讲:中国标准化发展的使命与愿景——《国家标准化发展纲要》解读
全球变化科学紫荆论坛第353期: 热带降雨季节循环的延迟
全球变化科学紫荆论坛第375期:极地观测与探测:现状与展望
公共卫生系列讲座:生物多样性保护及生态文明思想对人类健康的意义
报告题目:
Fabrication and characterization of carbon-based biomorphic composites
 报告人:
Dr. Dickon H. L. Ng
Associate Professor
Department of Physics
The Chinese University of Hong Kong.
报告时间:
2005-11-04 14:30
报告地点:
焊接馆301室
主办单位:
机械系
  简介:

Bioorganic substances like woods or cellulose fibers can be converted into high strength and lightweight carbide-reinforced biomorphic composites. The preparation of these composites involves several steps: (i) transforming natural bioorganic structures to carbon-based bio-templates by drying and pyrolysis, (ii) wetting the carbon bio-templates by infiltration of gaseous or molten metals, or metal-organic solutions, and (iii) converting the wetted bio-templates to functional composites by heat treatment. Biomorphic products, synthesized by this technique, possess bioorganic structures as well as having superior properties of engineering composites of carbides. This presentation describes the synthesis and characterization of biomorphic SiO2/SiC/C and SiC/C composites that contained SiO2 and β-SiC nanostructures. Freshly cut Luk Bamboo (Bambusa Textilis var Fusca) slices were used as our starting material and converted to bio-templates, and the metal-organic tetraethylorhosilicate solution was utilized as a source for Si. In characterizing the products, we found that the tubular structure of bamboo was retained. In addition, micron-sized spheres and nanorods of SiO2 were observed on the walls of the vessels in the samples treated at temperature around 1200oC, while β-SiC nanobelts were found in those samples treated at about 1400oC.

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