ANALYSIS OF Nb – Ni AND V – Ni BASED MEMBRANE CHARACTERISTICS

Abstract

To obtain ultrapure hydrogen by membrane technology, instead of expensive membranes made of Pd alloys, cheaper ones based on metals (Nb-Ni) and (V-Ni) are considered. Due to alloying of these Ti alloys, the performance of the membranes increased – diffusion and permeability of hydrogen, wear resistance and thermal stability, exceeding the Pd alloys. For crystalline analogs, the problem was also solved by increasing the Ti concentration with the formation of eutectic phases in ternary alloy compositions (Nb85-xTixNi15 and V85-xTixNi15). Hydrogen accumulated in membrane matrices forms specific polyhedral eutectic TСР hydrides up to phase transitions, and upon cooling from 673 to 303К under conditions of thermal expansion from 473 to 673К, it increases the temperature of β-hydride formation and forms NiTi and NiTi2 compounds, which stabilize and protect nano- and crystalline membranes from brittle destruction.

Keywords

• ti alloying
• ternary alloys nb-ni-ti
• v-ni-ti
• hydrogenation
• absorption
• diffusion
• hydrogen permeability
• phase formation
• me-h hydrides
• embrittlement
• duplex matrix microstructure