‘Green’ Cr(iii)–glycine electrolyte for the production of FeCrNi coatings: electrodeposition mechanisms and role of by-products in terms of coating composition and microstructure

Abstract

Electrodeposition mechanisms of a ‘green’ FeCrNi Cr(iii)–glycine electrolyte and their correlation with coatings' composition (metals/impurities), microstructure and elemental distribution variations.

Electrodeposition of Thick and Crack-Free Fe-Cr-Ni Coatings from a Cr (III) Electrolyte

“…The crystallite size of electroplated hard chrome is between 50 and 200 nm [23]. In the literature you can find a crystallite size of 20-25 nm for Fe-Cr-Ni layers [5]. An inverse Hall-Petch effect for nanocrystalline materials has been observed by a large number of researchers.…”

“…Crack propagation occurred when the thickness of the deposit exceeded the critical crack length, which is about 1 µm [14]. For Fe-Cr-Ni alloys, crack-free coatings with thicknesses less than 5 µm were observed [5]. Tests of Fe-Cr-Ni depositions produced from single and double cells showed clear differences in surface finish.…”

“…Only a few studies on Fe-Cr-Ni depositions have been conducted so far. Most studies dealt with the electrolyte composition and its influence on the distribution of the alloy composition as well as the effects on the microstructure [5][6][7][8]. Even fewer studies have dealt with the corrosion behavior of electroplated Fe-Cr-Ni coatings [9,10].…”

“…Even fewer studies have dealt with the corrosion behavior of electroplated Fe-Cr-Ni coatings [9,10]. Pure chromium and electroplated Fe-Cr-Ni deposits are nanocrystalline, which lead to high residual stresses and thus microcracks in the coatings [5,11]. A characteristic of almost all chromium coatings is the formation of microcracks, which are associated with the discontinuous evolution of hydrogen [12].…”

One-Pot Synthesis of Novel Molybdenum Disulfide–Graphene Oxide Nanoarchitecture: An Impeccable Bifunctional Electrode for the Electrochemical Performance of Iron Redox Flow Batteries and Oxygen Evolution Reaction

“…The reactions involved in the IRFBs are as follows: In the iron­(II) electrolyte, electrochemical additives were added to the electrolyte, which improve the stability of the electrolyte by avoiding the formation of the precipitate in the form of ferrous hydroxide. Here, the iron­(II) electrolyte composed of glycine is not only used as an additive, but it also acts as a buffer to avoid the variation of pH and very strong complexing agent to increase the stability of the iron­(II) electrolyte . Ammonium chloride (NH 4 Cl) increases the stability of the iron electrolyte by reducing the aerial oxidation, reducing the iron rust, and mainly minimizing the hydrogen evolution during the redox reaction.…”