Highly-Dispersed and Highly-Functional Ni Electrode Catalyst Prepared by a New CVI Method for Application to Molten Salt Type Fuel Cell

We aimed to prepare high -dispersed and high -functional Ni metal electrode catalyst of high化学和热稳定性A .A new chemical vapor infiltration （CVI）方法was explored to coat the surface of garbon fibers by tic for obtaining supporting materials ofmetals. The effect of反应条件such as temperature，time on stream and vapor pressure on TiC formation was系统性投资by heating acarbon fiber samplein a infra-red image furnace under ah_2 / ticl_4 mixed gas diluted with Ar. Tenkinds of carbon fibers, obtained from pitch，PAN and rayon等. by thermal treatment at different temperatureswere used as samples. TiC formation was evaluated by XRD， weight分析化学分析和SEM methods. Over all samples，the reaction was found to start over around 1000c虽然the conditions depended much on the preparation of raw materials， i.e.，especially their thermal treatment temperature. The time course of reaction，dependency on partial pressures and reaction temperature and the nonstoichimetric composition ofproducts (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，这产品测试作为一个suppour for Pt and Ni. 7% Pt/TiC//C prepared by animpregnation of h_2 ptcl_6 showed a high dispersion of 0.6，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 ionwith its stability up to 500 C in h_2. This is a promising valueconsidering that Ni is usually difficult to be finely dispersed on conventional supports. O

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