Methods for Controlling the Surface Architecture of Coatings Formed by Plasma Electrolytic Oxidation

The paper considers approaches that can lead to the growth of micro-and nanocrystals on the surface of coatings formed on valve metals by plasma electrolytic oxidation (PEO). Among these approaches, there are the use of electrolytes-suspensions, the addition of organic compounds to the electrolytes, the thermal annealing of ‘PEO layer/metal’ composites, including impregnated ones.

Corrosion–resistant materials for alkaline water electrolyzers

Commercially available materials for fabricating cell bodies, electrodes, pipes, and pumps for alkaline water electrolyzers, include conventional steels and stainless steels, nickel, valve metals, polymers, and other materials. In this review paper, most of these construction materials are briefly described and discussed. Special attention is given to presently produced nickel electrodes and novel nickel-based electrocatalysts for the hydrogen and oxygen evolution reactions in alkaline water electrolysis. It is shown that their electrocatalytic activity and corrosion resistance need to be improved in order to increase their commercial interest for alkaline water electrolyzers.

Formation of Coatings on Details from Valve Metals Alloys by Micro-Arc Oxidation in Internal Cavities of Counter Electrodes

It is shown that micro-arc oxidation (MAO), implemented according to traditional schemes in electrolytic baths with mechanical and pneumatic mixers, does not provide the formation of uniform ceramic coatings on the surfaces of holes, grooves and slots in the details from the alloys of the metals of valve group, and is characterized by a significant cost and relatively low safety. Fundamental possibility of MAO realization in the inner cavities of the special counter electrodes by passing solutions of electrolytes through them is installed. The calculated and experimental researches of MAO, applied to the processing of ball details from aluminum and titanium alloys, are conducted. The most rational design parameters of counter electrodes, as well as the rational parameters of the flow of electrolyte solutions in the clearances between the surfaces of details and counter electrodes are revealed. Innovative schemes for MAO of spherical details are developed. By measuring the thickness and hardness of the formed coatings it is proved that MAO, in the internal cavities of the counter electrodes, provides for the formation of more uniform ceramic coatings on the details from alloys of valve metals, in comparison with the traditional MAO in electrolytic baths with pneumatic and mechanical mixers.