Synthesis of Catalytic Cobalt-Containing Coatings on Alloy Al25 Surface by Plasma Electrolytic Oxidation

Abstract

The study aims at the investigation of the influence of electrolyte composition and plasma electrolytic oxidation modes on the composition and morphology of a mixed aluminum and cobalt oxides at the AL25 alloy. Composition, morphology Environmental and technical problems accompanying the operation of internal combustion engines (ICE) are associated with the incomplete combustion of fuel and, respectively, the inevitable formation of toxic components (CO, NO x , and soot). One of the perspective ways to improve the performance of ICE can be the use of catalysis in situ in the combustion chamber [1]. Catalytic processes are characterized by lower activation energies and consequently temperatures of the fuel burning start as well as its higher completeness [2]. These lead to a decrease in the maximum pressure in the combustion chamber and, hence, in the severity of engine operation and to the minimization of emissions of hazardous substances with exhaust gases.The currently available hydrocarbon fuel combustion catalysts are divided into two groups: catalysts based on noble metals (most commonly Pd and Pt) and transition-metal oxides (Mn, Co, Fe, etc.), particularly those with a complex composition [3]. At high temperatures, significant advantages are shown by a family of catalysts based on d-metals, in particular, cobalt oxides, which exhibit thermal lability and high oxygen affinity [4]. Nonstoichiometric cobalt oxides not only provide the thermal stability of the catalysts but also lead to a significant improvement of its reactivity.In terms of rational designing and effective technology, it seems appropriate to deposit a catalytic layer directly on the surface of ICE pistons manufactured using AL25 alloys with an optimal combination of physico-mechanical and performance properties [5]. The most promising method for the formation of thin layers on aluminum alloys, in particular, silumins, is plasma electrolytic oxidation (PEO). This method provides the incorporation of catalytically active components into an alumina matrix owing to the implementation of both electrochemical and thermo-chemical reactions in high-energy modes [6,7]. However, it should

Electrolysis Conditions Effect on the Vanadium-Containing Coatings Composition

“…Для водневої енергетики [1], а саме при електрохімічному виділенні водню, актуальним є отримання нових матеріалів, що мають каталітичні властивості в реакції відновлення водню на катоді (for the hydrogen evolution reaction (HER). Аналіз літературних даних дозволяє прогнозувати каталітичну активність в реакції відновлення іонів водню для матеріалів, що містять молібден, вольфрам та ванадій, та вважати перспективними електродними матеріалами покриття сплавами цих металів з металами підгрупи заліза [2].…”