HYDROGEN ABSORPTION KINETICS OF LaNi6 ALLOY

Hydrogen absorption kinetics of LaNi6-H system in alpha and alpha + beta phases has been investigated. Taking the reversibility of hydrogen absorption and desorption into account, an analytical solution has been obtained for the alpha phase. In a temperature range of 20-50 degrees C, the rate constant of hydrogen absorption, k(a), was found to be 0.08-0.41 s(-1) and that of hydrogen desorption, k(a), 4.8-25 MPa.s(-1) respectively.The apparent activation energy of hydrogen absorption was 35kJ(mol H-2)(-1). Hydrogen absorption in alpha + beta phase was slower than that of the alpha phase. The initial rate of hydrogen absorption is in first order with the hydrogen pressure used. The reaction is controlled by the dissociation of hydrogen on the alloy surface. With increasing of the reaction depth, the controlling step will shift to the reaction occuring on the alpha-beta interface. The rate constants are weakly dependent on the temperature. The hydrogen absorption rates on the initial and final stage of the pressure plateau in alpha + beta phase are obviously different.Chemistry, PhysicalSCI(E)中文核心期刊要目总览(PKU)中国科学引文数据库(CSCD)15586-594