| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1988: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1987: ¥900,000 (Direct Cost: ¥900,000)
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| Research Abstract |
We aimed to prepare highly-dispersed and highly-functional Ni metal electrode catalyst of high chemical and thermal stability, which could be applied to molten salt type tuel cell.
A new chemical vapor infiltration (CVI) method was explored to coat the surface of garbon fibers by tic for obtaining supporting materials of metals. The effect of reaction conditions such as temperature, time on stream and vapor pressure on TiC formation was systematically investigated by heating a carbon fiber samplein a infra-red image furnace under a H_2/TiCl_4 mixed gas diluted with Ar. Ten kinds of carbon fibers, obtained from pitch, PAN and rayon etc. by thermal treatment at different temperatures, were used as samples. TiC formation was evaluated by XRD, weight analysis, chemical analysis and SEM methods. Over all samples, the reaction was found to start over around 1000 ゜C, though the conditions depended much on the preparation of raw materials, i.e., especially their thermal treatment temperature. The time course of reaction, its dependency on partial pressures and reaction temperature and the nonstoichimetric composition of products (TiC_<0.8>) were examined intensively.
On a sample of active carbon fiber, an interesting texture of TiC,i.e., a felt-like porous structure consisting of fine TiC fibrils of ca. 0.1 micron, was obtained. This product was tested as a suppour for Pt and Ni. 7% Pt/TiC//C prepared by an impregnation of H_2PtCl_6 showed a high dispersion of 0.6, and it was stable up to 500゜C in H_2. However, TiC was oxidized at 400゜C in O_2, accompanying severe sintering of Pt particles. The degree of dispersion of 0.04 was attained on 5% Ni/TiC//C prepared by an impregnation of [Ni(CN)_4]^<-2> complex ion, with its stability up to 500゜C in h_2. This is a promising value, considering that Ni is usually difficult to be finely dispersed on conventional supports. O
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