Self-ignition combustion synthesis of LaNi5 utilizing hydrogenation heat of metallic calcium

Abstract

(173 words)This paper describes self-ignition combustion synthesis (SICS) of LaNi 5 in a pressurized hydrogen atmosphere using metallic calcium as both the reducing agent and the heat source. In this study, the effects of hydrogen on the ignition temperature and the hydrogenation properties of the products were mainly examined. In the experiments, La 2 O 3 , Ni, and Ca were dry-mixed in the molar ratio of 1:10:6 and then heated up at a hydrogen pressure of 1.0 MPa until the ignition due to the hydrogenation of calcium.For the sake of comparison, the same experiments were performed in a normal argon atmosphere. The results showed that the ignition temperature was drastically lowered by hydrogen; it was only 600 K in the case of hydrogen as compared to 1100 K in the case of argon. The products also exhibited high initial activity and hydrogen storage capacity of 1.54 mass%. The proposed method offers many benefits for using cost-effective rare-earth oxide, saving productive time and energy, improving initial activity of the product and applying to any AB 5 -type hydrogen storage alloy.

Combustion synthesis of TiFe by utilizing magnesiothermic reduction

“…The activation treatment was carried out shortly after the washing treatment, and involved activating and stabilizing the products seven times. In the activation treatment, at first, the P [18,21]. Hydrogen (H01 and H10) and argon (A01 and A10) atmospheres were used.…”

Self-ignition combustion synthesis of LaNi5 at different hydrogen pressures

“…A detailed explanation of both the apparatus and the preparation of samples is provided elsewhere [8,10]; only the framework of the experiments is described here. A watercooled chamber with a reactor and a graphite heater was used.…”

“…In a previous report, we proposed that SICS utilizing the hydrogenation heat of metallic calcium for the production of nickel rare-earth-based alloys such as LaNi 5 [10]. The proposed method resulted in the production of a hydrogen storage alloy of LaNi 5 using nickel and La 2 O 3 powders as raw materials and calcium grains as both the reducing agent and the heat source.…”