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

Abstract

The electrodeposition of iron-nickel-chromium coatings is a more environmentally friendly and economical alternative to hard-chrome coatings made from chromium (VI) electrolytes and stainless-steel bulk materials. The aim of the study was to develop a suitable deposition method for thick and low-crack Fe-Cr-Ni coatings. Iron-nickel-chromium coatings were electrodeposited using a more ecological chromium (III) electrolyte with direct current (DC), stepped direct current, and pulse current (PC). The influence of the deposition method on the electrolyte aging, the alloy composition of the coating, and their microstructure was investigated. Corrosion studies of the Fe-Cr-Ni coatings in 3.5% NaCl solution were performed using polarization tests. Furthermore, hardness measurements and scratch tests were carried out to determine the adhesion strength. Phase analyses were performed by X-ray diffraction, and the chemical composition and microstructure were characterized by scanning electron microscopy. Using the stepped DC and PC method, crack-free Fe-Cr-Ni coatings were successfully deposited.

Influence of the Current Regime during Electrodeposition in a Cr(III)-Containing Fe-Cr-Ni Electrolyte on the Near-Surface pH, Alloy Composition, and Microcrack Behavior

“…Likewise, a 2022 study on crack-free deposition of chromium layers from chromium(III) electrolytes found an optimum pulse-current ratio of pulse time t on = 1 s and t off = 5 s [12]. In another recent study on the influence of current shape during electrodeposition on the microcracking of applied Fe-Cr-Ni coatings, it was shown that under direct current, highly microcracked coatings were produced under various conditions [13]. A somewhat reduced crack pattern is shown with a deposition from pulse current [13,14].…”

“…In another recent study on the influence of current shape during electrodeposition on the microcracking of applied Fe-Cr-Ni coatings, it was shown that under direct current, highly microcracked coatings were produced under various conditions [13]. A somewhat reduced crack pattern is shown with a deposition from pulse current [13,14]. However, the layer thicknesses that can be applied for the same deposition time and current density are significantly lower, and the chromium content in the layers is 10% lower than that of the layers deposited under direct current.…”

Multi-Walled Carbon Nanotubes Modified NiCo2S4 for the Efficient Photocatalytic Reduction of Hexavalent Chromium

“…Chromium is usually present in two different oxidation states, hexavalent chromium (Cr(VI)) and trivalent chromium (Cr(III)) [4,5]. Cr(III) is less toxic in the environment and plays a vital role in metabolic processes as a trace metal essential to human nutrition [6,7]. In addition, it can be readily precipitated out of wastewater as Cr(OH) 3 in an alkaline or neutral solution and removed as solid waste.…”

Stressed State of Chrome Parts During Diamond Burnishing

“…Chromium coatings [38][39][40] and chromium-nickel coatings [41] are cathodic and have a more positive electrode potential in relation to steel, therefore, in the presence of through pores, corrosion products of the base are formed in them. Changing the electrical modes of electrolysis, the composition of the electrolyte, and the temperature of the electrolyte during electrochemical chromium plating ensures the production of coatings with different surface hardness and colour.…”