Evaluation of ultrasound wave frequency effects on the electroless Ni-PnanoAlumina coating by electrochemical impedance spectroscopy (EIS) method

Electroless nickel deposition was discovered in 1946 by Brenner and Riddell [1]. These coatings are produced by the catalytic reduction of nickel ions using sodium hypophosphite as a reducing agent [2]. The nickel–phosphorous (Ni–P) deposits obtained from electroless plating which is an autocatalytic process are widely used in different industries for their unique combination of properties such as wear resistance, corrosion resistance, and higher hardness [3]. In the present project, electroless nickel phosphorous coatings in the presence of nanoparticles were studied by using ultrasound waves on mild steel. In this regard, Ni-P composite coatings containing alumina nanoparticles prepared with sonoelectroless autocatalytic method using an ultrasound probe. On the other hand, the wavelength effects of the ultrasound waves on the properties of the coatings is studied. Corrosion performance of the coatings was examined by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The surface morphology and composition of the composite coatings were characterized by scanning electron microscopiy (SEM), energydispersive X-ray spectroscopy (EDX) measurements and X-ray diffraction (XRD) analysis. The tribological properties of the surface have been investigated. Results show that by increasing the ultrasound wave frequency up to certain amount, the corrosion resistance of coating increases. There is an specific optimum ultrasound wave frequency for coats.