アークイオンプレーティング法によるNb-Mo合金膜の作製および水素脆化

Abstract

In the case of H2 production via steam reforming of CH4, it is necessary to prepare a hydrogen-permselective membrane without pin-holes and cracks. The formation of metal hydride causes cracks in the membrane, resulting in hydrogen embrittlement. Hydrogen embrittlement was prevented by alloying the membrane with a metal such as Mo which does not form a hydride. Moreover, high H2 permeation is expected by the alloying. In general, a hydrogen permeable metal has a high melting point. As the alloying of high melting point metals is difficult, there have been few papers on an alloy membrane of high melting point.In this study, a Nb hydrogen-permselective membrane was alloyed with Mo at 1.3 Pa of Ar gas pressure by Physical Vapor Deposition (PVD) method such as arc-ion plating (AIP). Two targets of Nb and Mo were used. Vegard’s law was observed in the Nb-Mo alloys.After the cyclic H2 absorption/desorption test in 1×105 Pa H2, the formation of Nb hydride was confirmed in the Nb membrane, but metal hydride was not observed in the Nb-Mo alloy membrane. It was estimated from the lattice strain that the Nb-10 at%Mo alloy showed the highest H2 permeation.