Functional ternary cobalt alloys

Abstract

The functional properties of ternary Co-Mo-W and Co-Mo-Zr alloys obtained in galvanostatic and pulsed modes from pyrophosphate-citrate electrolytes are discussed. The effect of the alloy nature on the corrosion resistance and micro hardness of electrode materials based on cobalt with refractory metals has been studied. The coating was applied from complex pyrophosphate-citrate electrolytes on steel substrates. The composition of the alloys was determined by X-ray fluorescence analysis via a portable Sprut spectrometer. The relief and surface morphology were analyzed according to scanningelectron (SEM) and atomic force microscopy (AFM) data. The corrosion resistance of the coatings was investigated using the electrode impedance method. Vickers microhardness was determined by indentation of a diamond pyramid. The obtained coatings have a uniformly developed surface with the presence of cracks on the grid surface, which is associated with internal stress at a sufficiently high content of refractory components. The roughness parameters Ra and Rqare 0,1-0,2 for Co-Mo-Zr, and five times less for Co-Mo-W. The corrosion resistance of the Co-Mo-W alloy corresponds to a corrosion rate below 0,05 mm/ year, which indicates the material chemical resistance. The corrosion resistance of the Co-Mo-Zr coated electrode is an order of a higher magnitude compared to Co-Mo-W, which provides a depth indicator of less than 0,01 mm / year and allows considering such coating as a highly resistant in aggressive environments. It has been established that the general trend is the increasing hardness of Co-Mo-W alloys coatings with increasing content of refractory components. The high values of micro hardness and corrosion resistance of ternary Co-Mo-W and Co-Mo-Zr alloys coatings make it possible toconsider them as a promising electrode materials of chemical current sources, and also as a replacement for chrome electroplating coatings used in automobiles