Iron-containing coatings obtained by microplasma method on aluminum with usage of homogeneous electrolytes

Magnetic characteristics of iron-modified oxide layers on titanium

“…The transition metals from the electrolyte were concentrated on surface defect sites (mostly in pores formed by electric dis charges) in the form of conglomerates of nanoparticles (~50 nm) or microcrystals containing reduced iron [3,5,8,9]. The concentration of iron in the pores was also observed during the formation of coatings in an elec trolyte with complex EDTA + Fe 3+ ions [7]. Note that the conditions for the formation of colloidal particles of hydroxides-precursors of magnetically active compounds-directly in the electrolyte for PEO, on the one hand, do not require the introduction of nano or microparticles of metals or their oxides and, on the other hand, allow us to introduce different metals or their mixtures into the pores of the coatings and thus impart certain magnetic characteristics to them.…”

“…In recent years, it has been shown that iron and/or cobalt containing oxide coatings with ferro , ferri , or antiferromagnetic properties can be formed on alumi num or titanium substrates by an unconventional sin gle stage method: anodization in aqueous electrolytes at sparking and microarcing voltages (microarc or plasma electrolytic oxidation, PEO) [1][2][3][4][5][6][7][8][9]. Precursors containing cobalt or iron compounds are introduced into electrolytes either in the composition of solid micro and nanoparticles (Fe 0 , Co 0 , or Fe 2 O 3 ) [1,4,6] or in the form of complex compounds (EDTA + Fe 3+ ) [7].…”

The effect of nanocrystallites in the pores of PEO coatings on their magnetic properties

“…Upon one-stage PEO technique the magneto-active elements are concentrated in the pores [3,5] or the defects of the surface [14]. In this case the simulation showed [19] that the composites 'Fe-containing PEO coating/valve metal' can have ferromagnetic clusters which consist of chemically inhomogeneous particles or a mixture of particles with very different magnetic properties.…”

“…1). The first is one-stage PEO technique when precursors of magneto-active compounds are directly involved into forming electrolyte as complex compounds ([Co(EDTA)] − [5], [Fe(P 6 O 18 )] 3 − [14]) or in the compositions of solid micro-and nanosized particles (Fe 0 , Co 0 or Fe 2 O 3 ) [1,4]. Furthermore, the conditions for the formation of solid particles can be created directly in the electrolyte for PEO, for example, as a result of iron or cobalt hydroxide precipitation in phosphate-borate-tungstate solution after addition of appropriate oxalate or acetate [3,14,15] and their hydrolysis in alkaline medium.…”

“…To obtain such composites one can use plasma electrolytic oxidation (PEO) technique [1,[3][4][5] that is electrochemical oxidation of valve metals under spark and microarc electric discharges [6][7][8][9][10][11][12][13].…”