CORROSION BEHAVIOR OF THE ELECTROLYTIC TERNARY COBALT ALLOYS WITH Mo(W) AND Zr IN ALKALINE SOLUTION

Abstract

The ternary Co–Mo–W(Zr) coatings with total content of refractory metals of 30–40 wt.%, and Co–W–Zr alloys (12–26 wt.%) are deposited from pyrophosphate-citrate electrolytes in pulse regime. The composition of the coatings as well as the surface morphology depends on the current density. The X-ray diffraction patterns reflect the amorphous-and-crystalline ternary alloys structure. Phases of α-Co, Co–Mo intermetallic compounds, and traces of metallic molybdenum were detected in the Co–Mo–Zr coatings. Phase composition of Co–Mo–W deposits differs by emergence of Co7W6 phase and traces of metallic tungsten, and there is no metallic W in Co–W–Zr electrolytic alloys. The corrosion behavior of ternary coatings in alkaline medium studied by EIS shows that Co–Mo–Zr alloys are characterized by highest corrosion resistance among deposited coatings due to presence of metallic molybdenum and stoichiometric ZrO2 with both high electrical resistivity and chemical stability. The coatings Co–Mo–W and Co–Mo–Zr containing phases of Mo or W are characterized by higher corrosion resistance as compared with that without metallic molybdenum and tungsten. The cyclic voltammetry data confirm stability of ternary coatings in alkaline solution under anodic polarization. Such properties as well as the developed globular surface make materials promising for use as anodes in fuel cells in particular based on alkali electrolytes.

Електролітичне Окиснення Глюкози На Композиційних Молібденвмісних Покриттях Кобальту

“…The glucose oxidation mechanism consists [20] of the following stages: glucose in the form of a closed ring (α-or β-modifications) is subjected to the oxidation with the formation of glucono-β-lactone by the 2-electron reaction [21]:…”

Електродні Матеріали Для Водневої Енергетики

“…На каталітичне виділення водню впливає як склад отриманих покриттів, так і характеристики їх поверхні. Раніше було встановлено, що до складу покриттів сплавами кобальту поряд із основними компонентами входять кисень і вуглець [11]. Причому, вміст вуглецю практично не залежить від режимів осадження і складу сплаву, але спостерігається тенденція до збільшення відсотка цирконію і кисню при підвищенні густини струму.…”