Characterization of Ni-P-SiO2-Al2O3 nano-composite coatings on aluminum substrate

• Published in: Materials chemistry and physics Vol. 189; pp. 207 - 214
• Main Authors: Rahemi Ardakani, S., Afshar, A., Sadreddini, S., Ghanbari, A.A.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.03.2017; Elsevier BV
• Subjects: Aluminum alloys; Aluminum base alloys; Aluminum oxide; Coatings; Corrosion; Corrosion rate; Corrosion resistance; Electrochemical impedance spectroscopy; Electrochemical techniques; Emission analysis; Field emission microscopy; Microhardness; Nanocomposites; Nanostructures; Nickel; Porosity; Protective coatings; Silicon dioxide; X-ray diffraction topography; X-ray diffraction topography; Electrochemical techniques; Nanostructures; Corrosion; Coatings
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2016.12.023

In the present work, nano-composites of Ni-P-SiO2-Al2O3 were coated on a 6061 aluminum substrate. The surface morphology of the nano-composite coating was studied by field emission scanning electron microscopy (FESEM). The amount of SiO2 in the coating was determined by Energy Dispersive Analysis of X-Ray (EDX) and the crystalline structure of the coating was examined by X-ray diffractometer (XRD). All the experiments concerning the corrosion behavior of the coating carried out in 3.5%wt NaCl solution and evaluated by electrochemical impedance spectroscopy (EIS) and polarization technique. The results showed that an incorporation of SiO2 and Al2O3 in Ni-P coating at the SiO2 concentration of 10 g/L and 14 g/L Al2O3 led to the lowest corrosion rate (icorr = 0.88 μA/cm2), the most positive Ecorr and maximum microhardness (537 μHV). Furthermore, increasing the amount of nanoparticles in the coating was found to decrease CPEdl and improve porosity. [Display omitted] •The maximum content of Al2O3 and SiO2 in the coating was increased to 14.02%wt and 4.54%wt, respectively.•By enhancing the amount of nanoparticles in the coating, there was higher corrosion resistance.•Increasing the nanoparticles content in the coating improved microhardness of coating.•The maximum of microhardness of Ni-P-SiO2-Al2O3 was measured to be 537 μHV.