In electrochemistry, a valve metal is actually a metal which passes latest in only one path. Ordinarily, in an electrolytic cell, it might functionality normally to be a cathode, although not usually as an anode for the reason that a (extremely resistive) oxide on the metal varieties under anodic problems. https://hardtofindvalves55433.blogerus.com/39774831/hard-to-find-valves-an-overview