Friction surfaced coatings obtained by vertical feed-rate controlled deposition exhibit stable electrochemical behavior as a function of rotation speed during deposition

Abstract

In order to improve corrosion resistance of structural elements, stainless-steel coatings can be employed thus allowing a relatively low-cost carbon steel substrate to be protected against potentially hazardous environments. In the present work, austenitic stainless-steel coatings were produced by friction surfacing, with constant horizontal (190 mm/min) and vertical (95 mm/min) feed rates and rotation speed values of 1300, 1500, 1700, 1900 and 2100 rpm. The average dynamically recrystallized grain size (d_DRX) on the coatings surface was determined by optical microscopy as a function of deposition conditions, allowing subsequent correlations with different parameters obtained from potentiodynamic polarization scans and electrochemical impedance spectroscopy analyses in 0.5 M H₂SO₄ and 0.6 M NaCl to be investigated. EDX analyses were performed along the thickness of coatings to evaluate possible variations in the (Cr, Ni and Mo) contents of mechtrode material (alloy 316L), and it was possible notice that the increase in rotation speed contributed to producing a coating with more homogeneous chemical composition. In both investigated electrolytes, the variation of rotation speed did not significantly influence the corrosion resistance of the deposited coatings, evidencing that the friction surfacing process delivers stable output in terms of electrochemical performance even when varying parameters over a relatively wide range (1300–2100 rpm rotation speed).