Evaluation of corrosive behavior of chromium silicon nitride under hydrodynamic conditions in aggressive environments

Abstract

In order to analyze corrosion resistance and wear behavior, steel cylinders were coated with chromium silicon nitride via physical vapor deposition, using a reactive sputtering magnetron, with base and working pressures of 4*10−6 mbar and 8*10−3 mbar respectively. The diffraction patterns correspond to chromium nitride and the amorphous phase of silicon nitride, hardness of 6.52 GPa, thickness of 3 μm and chemical composition characterized by nitrogen, silicon and chromium. The corrosion behavior was determined with a rotating cylinder electrode, rotating at different speeds and connected to a Gamry potentiostat galvanostat, using the techniques of polarization resistance, electrochemical impedance spectroscopy and dynamic potentiation polarization. The tests were carried out in solutions composed of water, 1% of sodium chloride and silica sand, with temperatures of 25 °C and 45 °C. Limiting current density behavior was evidenced. The coating corrosion rate was reduced by up to two orders of magnitude compared to that found for steel samples and was affected by the system rotation speed, particle size and electrolyte temperature.