Laser and electron beam processing of electrodes consisting of amorphous nickel-valve metal-platinum-group metal surface alloys on valve metals

Abstract

When melt-spun amorphous nickel-valve metal alloys containing small amounts of platinum-group metals are activated by immersion in HF solutions they exhibit unusually high activities for chlorine evolution in electrolysis of NaCl solutions. In order to eliminate a high electrical resistance resulting from the thickness limitation of melt-spun amorphous alloys, laser and electron beam processing was successfully used to prepare amorphous NiNbplatinum-group surface alloys having superior electrocatalytic activity on niobium by using specimens composed of a niobium substrate on which nickel and platinum-group metals were electro-deposited. The composition range vitrifiable over a wide area is significantly narrower than that vitrifiable by conventional methods for the preparation of amorphous alloys because overlapped traverses by the beams for vitrification of a wide area often result in crystallization in the heat-affected zone in the previously vitrified phase. The electron beam, which exhibits almost no reflection by metals, is more convenient and effective for processing than the laser beam, which has a high reflectance by metals.