The effect of the conditions of formation on ferromagnetic properties of iron-containing oxide coatings on titanium

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

“…Insofar as the oxygen content is insufficient for the formation of oxides, metals are present in the crystallites in a partially or predominantly reduced state. The presence of reduced iron in PEO coatings was found previously by XPS [20] and XRD [21].…”

“…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. Scanning electron microscopy of high resolution confirmed the presence of agglomerates of nanoparticles in the pores of PEO coatings [15,[20][21][22]. The particles in the pores of the coatings formed on titanium in phosphate-boratetungstate electrolyte (PBW-electrolyte) with addition of iron oxalate contain (at.…”

“…The particles in the pores of the coatings formed on titanium in phosphate-boratetungstate electrolyte (PBW-electrolyte) with addition of iron oxalate contain (at. %) 51.0 Fe, 13.5 Ti, 19.2 O, 7.2 C, 2.2 P, 1.7 Na, 5.2 W and seem to be the species of reduced metals encapsulated in oxidehydroxide shell [20]. X-ray diffraction (XRD) [21] and X-ray photoelectron spectroscopy (XPS) [20] confirm the presence of reduced iron in PEO coatings.…”

Magnetic characteristics of iron-modified oxide layers on titanium

“…It was proposed that a base alkaline solution of Na 3 PO 4 + Na 2 B 4 O 7 + Na 2 WO 4 (PBW) with iron(III) oxalate and/or cobalt(II) acetate additives can be used to form ferromagnetic oxide coatings on aluminum and titanium via PEO [2,3,5,8,9]. Introducing these salts into the base electrolyte by means of hydrolysis leads to the formation of slurries containing dispersed (colloidal) particles of metal hydroxides.…”

“…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].…”