Composition, structure, and corrosion properties of coatings of Co-W alloys electrodeposited under direct current

Abstract

A correlation has been found between the composition, structure, and corrosion resistance of electrolytic Co-W coatings (on the basis of voltammeter and impedance measurements at pH-6.0 in a chloridesulfate model solution) deposited at various densities of direct current from citrate electrolyte with a high concentration of sodium tungstate with addition of boric acid at a temperature of 58 ° C. It is found that these coatings possess a high corrosion resistance that is only insignificantly inferior to that of electrolyte chromium coatings. We have determined the interval of current densities of electrodeposition in which corrosion resistance of the coatings is maximum.

Research into influence of the electrolysis modes on the composition of galvanic Fe-Co-Mo coatings

“…An inclusion (Incorporation) into the composition of coatings of tungsten and molybdenum makes it possible to inherent internal stresses in the electrolytic alloys of iron, and to improve low adhesion [12] as well as the physicalmechanical properties of coatings [13].…”

Evaluation of Corrosion and Tribological Behavior of Electrodeposited Tungsten Alloys

“…After adding SO 4 2-ions to the neutral corrosive medium containing NaCl, the corrosion resistance of Co-W alloys slightly depends on the coating thickness. Thus, it was depicted that the corrosion current density decreases from 4.610 -5 (for thin coatings) to 1.4 10 -5 A cm -2 (for 20 µm), meanwhile the corrosion potential for both samples was similar -0.60±0.05 V [48]. It was not determined a clear correlation between the tungsten content in the deposit and corrosion current density in NaCl + Na 2 SO 4 solution neither for Co-W nor Fe-W alloys [13,48] (Fig.…”

Tribological and corrosive characteristics of electrochemical coatings based on cobalt and iron superalloys

“…The other reason is that such coatings are nanocrystalline [7,8,21,22]. Amorphous or nanocrystalline coatings from the above alloys have specific wear and corrosion characteristics [23][24][25][26][27][28] and can be used for the electrolytic formation of microelectromechanical systems (MEMS) and nanosystems (for example, nanowires and nanotubes) [29][30][31]. Nanocrystalline alloys of tungsten with iron-group metals may sometimes replace platinum catalysts [32,33].…”