Nanostructured surfaces

Nanostructured mixed oxide coatings incorporated by transition and refractory metals on silumin
A.V. Karakurkchi, N.D. Sakhnenko, M.V. Ved’, M.V. Mayba
National Technical University “Kharkiv Polytechnic Institute”, Kyrpychova Str. 2, Kharkiv-61002, Ukraine.
E-mail: anyutikukr@gmail.com

Nanostructured mixed oxide coatings Al2O3·MOy (M = Co, Mn, Mo) were obtained on silumin AK12M2MgN by plasma electrolytic oxidation (PEO) at direct current. Electrochemical treatment performed in aqueous pyrophosphate electrolytes with addition salts of metal-dopants or oxoanions. Current density of the formation was of 1‒20 A/dm2, operating voltage ‒ up to 240 V. The time of coatings formation was 2–60 minutes. PEO was implemented in an electrolytic cell under conditions of forced cooling of the electrolyte to a temperature of 25–30°C and its stirring.
It is established that the quantitative characteristics of the PEO stages depend on the composition of the electrolytes. The most significant incorporation of dopants into the oxide layers are achieved in micro-arc mode. Varying the operating current density also affects the change in the morphology of the coatings surface. As a result of PEO aluminum oxide matrix has been incorporated with remelts of the electrolyte and alloy components [1]. The content of doping components in ceramic-like coatings ω is up to, at%: Co – 24, Mn – 35 and Мо – 10. Oxide coatings are uniform, have low-porosity, high adhesion to the substrate and a sufficiently developed surface formed of spheroid and cone-shaped structures. The composition, morphology and surface topography of mixed oxide systems predetermine their high catalytic activity in red-ox reactions. The synthesized oxide materials are tested in model reactions of CO and benzene oxidation. Stand tests of single-cylinder diesel engine with catalytic coatings show a reduction in hourly fuel consumption and reduce toxic emissions at forced modes of engine operation [2].

1.	Karakurkchi A., Sakhnenko N., Ved’ M. and etc. Application of oxide-metallic catalysts on valve metals for ecological catalysis // East.-Europ. J Enterpr. Technol.-2017.-5/10 (89).-P. 12-18.
2.	Parsadanov I., Sakhnenko N., Ved’ M. and etc. Increasing the efficiency of intra-cylinder catalysis in diesel engines // Vopr. Khim. i Khim. Tekhnol.-2017.-6.-P. 75-81.