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

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.