Fabrication In-Situ SiC Nanowires/SiC Matrix Composite by Chemical Vapor Infiltration Process

Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
Materials Letters (Impact Factor: 2.49). 10/2004; 58(25):3145-3148. DOI: 10.1016/j.matlet.2004.05.059


A SiC nanowires-reinforced SiC matrix composite was fabricated using chemical vapour infiltration (CVI) process. SiC nanowires with thin carbon coating were grown directly in a fibrous preform prior to the CVI matrix densification. The nanowires consist of single crystal β phase SiC and uniform carbon shell coating of ∼5 nm, with diameters of several tens to 100 nm. The volume fraction of the nanowires in the fabricated composite is ∼5%. Contributions of the nanowires to the mechanical properties of the composite are expected.

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    • "Consequently, they are widely used to fabricate structural and functional composites for extremely harsh environment [4] [5]. Nowadays, various synthesis methods have been explored to produce β-SiC whiskers, including chemical vapor deposition using silicon precursor [6] [7] [8], carbon template of carbon nanotubes to β-SiC whiskers [9] [10], thermal evaporation [11] [12], carbothermal reduction [13], etc. Generally, the growth mechanisms of SiC whiskers are involved in vapor–solid (VS) and vapor– liquid–solid (VLS) mechanisms [14] [15] [16] [17]. "
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    ABSTRACT: Silicon carbide whiskers have been synthesized by using reactive graphite as a template. Natural graphite flake was firstly activated using chemical oxidation and thermal oxidation methods. After that, the reactive graphite sources were mixed with silicon powder and heated in the coke bed at 1200 and 1400 °C. The structural evolution of graphite and morphologies of SiC whiskers were studied with the aids of XRD, SEM, TEM and EDS techniques. The results showed that natural graphite flake can be activated into reactive graphite such as oxidized graphite and expanded graphite with much more defects using thermal and chemical oxidation methods. The expanded graphite with a great deal of defects has higher reactivity than natural graphite flake and oxidized graphite and accelerates the formation of long and thick SiC whiskers. It is proposed that the vapor–solid mechanism is predominant for the growth of β-SiC whiskers in this system. During heating-up, Si or SiO vapors meet with the activated carbon atoms on graphite substrate to form SiC nucleus. Then these vapors continually deposit on the SiC nucleus following the SiC whiskers which grow along the 〈111〉 direction.
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    • "Thus, regardless of their favorable biological properties, the poor mechanical properties of HAp bioceramics have severely hindered their clinical applications (Hench 1991; Yaszemski et al. 1996). Therefore, a number of studies have been focused on the improvement of the mechanical properties of HAp bioceramics (Shen et al. 2001; Suchanek et al. 1997), and studies have shown that the mechanical properties of the ceramics could be reinforced remarkably by one dimensional (1-D) nanoscale building blocks such as nanorods, nanofibers, and nanotubes (Ramay and Zhang 2004; Yang et al. 2004; Kobayashi and Kawai 2007). However, ultrastructural examination of deproteinated bone reveals that individual 25–50 nm HAp crystal is the essence of bone in terms of mechanical properties and bioresorbability, and plays an important role in biomineral formation (Shi et al. 2009). "
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    Vehicular Technology Conference, 2001. VTC 2001 Spring. IEEE VTS 53rd; 02/2001
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