Electrodeposition of Alloys of Rhenium with Iron-Group Metals from Aqueous Solutions

摘要

Rhenium is a refractory metal that has gained significant recognition as a high-performance engineering material. Rhenium has the 2~(nd) highest melting point of all metals (after W), the 3~(rd) highest Young's modulus of elasticity (after Ir and Os), and the 4~(th) highest density (after Os, Ir and Pt). It also has one of the highest strain hardening exponents of all elements, low coefficient of friction and high hardness, consequently having excellent wear properties. Compared with other refractory metals, it has superior tensile strength and creep-rupture strength over a wide temperature range (up to about 2000℃). While the other refractory metals have a body centered cubic (bcc) structure, Re has a hexagonal close-packed (hcp) structure. Consequently, it does not possess a ductile-to-brittle transition and, therefore, can safely be used at subzero temperatures. Rhenium is the only refractory metal that does not form carbides. Yet, the solubility of carbon in Re is fairly high and the wettability is also high; thus, excellent bond strength can be achieved between these two elements. Indeed, Re is used in contact with graphite and carbon composites. Rhenium is highly resistant to corrosion in hydrochloric and sulfuric acids as well as in seawater. It also has low permeability to hydrogen and resists attack in hydrogen and inert atmospheres at elevated temperatures (1-5).