HYDROGEN ABSORPTION AND DESORPTION CHARACTERISTICS OF FERRO-TITANIUM ALLOYS

HYDROGEN ABSORPTION AND DESORPTION CHARACTERISTICS OF FERRO-TITANIUM ALLOYS

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JOURNAL OF MATERIALS SCIENCE 16 (1981) 2527-2530 Hydrogen absorption and desorption characteristics of ferro-titanium alloys MASAHI RO KITADA Central Research Laboratory, Hitachi Ltd, Tokyo 185, Japan Hydrogen absorption and desorption characteristics of commercially supplied ferro- titaniums with 41 to 51 at% Ti have been studied. The characteristics are similar to those of high purity FeTi although the ferro-titaniums include some impurities. The activation temperatures of the ferro-titaniums are slightly higher than that of the high purity FeTi. Plateaus in the hydrogen absorption and desorption curves are not obvious compared with those of high purity Fe-ri. ~t is concluded that the ferro-titaniums are good, low- cost hydrogen storage materials~ Io ~ntroduction The intermetallic compound iron-titanium has been developed as a hydrogen storage material [11 and attempts have been made to use it in hydrogen fuel cars and for storing energy in elec- tric power stations, water pumps and reservoirs [2]. The compound forms a hydride, FeTiH2 [1]. For this hydride to be commercially useful, the cost of materials must be lowered. Ferro-titanium has been used to make special steels. The ferro-titanium usually contains some impurities. However, this material is expected to be used industriaily as a hydrogen storage material in place of the high purity one. As a result the feasibility of ferro-titanium as a hydrogen storage material has been confirmed in this experiment. Since large amounts of ferro-titanium have been fabricated to make special steels, the pro- duction techniques are well established. Ferro- titanium usually contains some impurities, for example, A1, Mn and Si. It is thought that these impurities affect the hydrogen storage capability of ferro-titanium. In this work, first the acti- vation conditions necessary to make the alloys absorb hydrogen easily have been studied and the hydrogen storage abilities investigated. 2. Experimental procedure Three ferro-titanium specimens with different compositions were used. Titanium contents of the specimens were 41, 46 and 51 wt%; the main impurities were Mn, ALl, Si, Cu and C. The names 0022-2461/81/092527-04502.40/0 and compositions of the specimens are shown in Table I. The specimens were spongy. The speci- mens were crushed to a powder with an average particle diameter of 10/~m. The powders were put in stainless steel specimen holders to examine their activation and hydrogen absorption behav- iours. To evaluate the hydrogen absorption charac- teristics of the specimens the intermetallic com- pound FeTi was prepared using high purity iron and zone refined titanium. The reactions between hydrogen and the alloys were examined by high pressure differential thermal analysis [3] (HDTA) under a hydrogen atmosphere. The absorption-desorption character- istics were determined by pressure-composition measurements. The hydrogen desorption rate from the hydride was obtained by measuring the
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HYDROGEN ABSORPTION AND DESORPTION CHARACTERISTICS OF FERRO-TITANIUM ALLOYS

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