Heterogeneous Metal Oxide Coatings with Magnetoactive Nickel, Cobalt, and Iron Phases Formed by the Method of Pulsed Microplasma Oxidation for Radiation Absorption in the Middle and Near-IR Regions

Abstract

Heterogeneous coatings with high ability to absorb electromagnetic radiation in the middle (4000–400 cm–1) and near-IR regions (11000–2000 cm–1) are formed by the method of pulsed microplasma oxidation on aluminum and titanium alloys in inorganic electrolytes containing nickel, cobalt, and iron compounds. The electromagnetic radiation absorption is provided not only by the oxide coating itself, but also mainly by the heterogeneous metal particles of nickel, cobalt, and iron forming a dispersed metal phase and having magnetic properties that are incorporated into the coating pores by the method of microplasma oxidation under the action of a constant magnetic field. The influence of the electrolyte compositions and of the parameters of pulsed microplasma oxidation on the structure, composition, and radiation absorption properties of coatings is studied. It has been revealed that coatings formed in a phosphate-borate electrolyte with addition of nickel at a voltage of 300 V, a pulse duration of 100 μs, and a process duration of 5 min have the best absorption ability.