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Diagnostic of the erosion corrosion evolution by cavitation of [TiN-TiAlN]<inf>200</inf> thin coatings

Abstract:

In this work is presented the results of the corrosion erosion resistance evaluation by cavitation of the thin films in multilayers form of TiN/TiAlN deposited with 200 bilayers period onto AISI 4140 steel substrates, by means of magnetron sputtering system with reactive r.f. from high purity targets of Ti and Al (99.99%) in an atmosphere composed by Ar/N. The test was performed with a high frequency generator and the sample immersed in a liquid containing sodium chloride. The electrochemical characterization was performed using the techniques of electrochemical impedance spectroscopy and Tafel polarization curves. The microstructural characterization was obtained by scanning electron microscopy. It was state that the coatings subjected only to the phenomena of erosion produced by cavitation generate low damages, due to the material loss is minimum. However, when the coatings are subjected to simultaneous corrosion and erosion damage by cavitation the deterioration is high, owing to the synergy of the two evaluated mechanisms. © 2014 The Authors.