Two different batches of CFRC composites were prepared in the absence / presence of B with the expectation of increasing oxidation stability and improving the processing compatibility of CFRC composites in commercial applications. The composites were examined to reveal the nature of substitutional B
Oxidation inhibition effects of phosphorus and boron in different carbon fabrics
โ Scribed by Young-Jae Lee; Ljubisa R. Radovic
- Publisher
- Elsevier Science
- Year
- 2003
- Tongue
- English
- Weight
- 441 KB
- Volume
- 41
- Category
- Article
- ISSN
- 0008-6223
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โฆ Synopsis
To improve oxidation inhibition, elemental boron and two phosphorus compounds were doped into an activated carbon cloth and a carbon felt. The hypothesis was that P can block active sites by virtue of the formation of C-P-O or C-O-P bonds at graphene edges while substitutional B can alter the chemical reactivity of the residual free active sites by reducing the electron density in the graphene layer. To increase the final dopant concentration, the carbon felt was activated in nitric acid. The crystallinity of activated carbon cloth was improved by heat treatment and substitutional B; that of carbon felt was also improved, but not necessarily due to substitutional B. In all cases the oxidation reactivity is suppressed by heat treatment and in the presence of dopants. The oxidation inhibition mechanism in P-doped samples appears to be active sites blockage because of a proportional increase of oxidation inhibition with increasing P loading. The results for B-doped samples are consistent with our previous studies in which B was found to exhibit both a catalytic and an inhibiting effect on carbon oxidation. Samples doped with both P and B showed the most effective oxidation inhibition and their oxidation behavior is described in detail.
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Carbon supported catalysts can lose their activity over a period of time due to the sintering of the nanometer-sized catalyst particles. The sintering of metal clusters on carbon supports can occur due to the weak interaction between the metal and the support and also due to the corrosion of carbon,