Application of Ni-P-ZrC Nanocomposite Coating by Electroless Plating Method and Investigation of its Mechanical and Electrochemical Properties and also Investigation of the Electroless Plating Possibility at Low Temperature

Shoghi, Payam (2017) Application of Ni-P-ZrC Nanocomposite Coating by Electroless Plating Method and Investigation of its Mechanical and Electrochemical Properties and also Investigation of the Electroless Plating Possibility at Low Temperature. Masters thesis, University of Mohaghegh Ardabili.

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Text (اعمال پوشش نانوکامپوزیتی نیکل- فسفر- کاربید زیرکونیوم به روش آبکاری بدون برق و بررسی خواص مکانیکی و الکتروشیمیایی آن و همچنین بررسی امکان آبکاری بدون برق در دمای پایین) Peyam Shoghi.pdf Download (785kB) | Preview

Abstract

In the first part of the present thesis, zirconium carbide (ZrC) nanoparticles were loaded to the electroless Ni-P bath in order to synthesize the Ni-P- ZrC nanocomposite coatings. Scanning Electron Microscopy (SEM) showed that pore-free, compact, and columnar Ni-P-ZrC nanocomposite coatings without inter-columnar corrosion defects were successfully applied on the brass substrate by addition of 0.1 and 0.2 g. L-1 ZrC nanopowders into the plating bath. The co-deposition of the ZrC nanoparticles was verified by Energy Dispersive X-Ray Spectroscopy (EDS) technique. Moreover, uniform distribution of the imbedded nanoparticles was shown by the EDS mapping. Diffraction peaks of the incorporated nanoparticles were not observed in X-Ray Diffraction (XRD) pattern of the Ni-P-ZrC nanocomposites may be due to homogenous distribution and low conventration of the nanoparticles. Electrochemical Impedance Spectroscopy (EIS) and pH metric measurements in the plating bath revealed that electrostatic attraction acts as an effective factor to trap the nanoparticles in the matrix of the Ni-P-ZrC nanocomposites. The anti-corrosion characteristic of the Ni-P deposit in 3.5 wt. % NaCl corrosive electrolyte and their microhardness were significantly improved by the co-deposition of the ZrC nanoparticles. In the second section of the thesis, Electrochemically Promoted Electroless Plating (EPEP) was used to apply pretreatment–free Ni–P coating on AM60B magnesium alloy from a low–temperature electroless bath. Different surface analysis methods including SEM, AFM, EDS, and XRD were utilized to assess the morphology, roughness, elemental composition, and microstructure of as–deposited Ni–P coating, respectively. compact, uniform, and medium–phosphorus Ni–P coating with mixed crystalline–amorphous microstructure was applied on the alloy surface by 4 mA. cm-2 impressed cathodic current at 50 °C without any especial pretreatment. Also, it was shown that only island–like nickel deposits can be achieved on the magnesium at the same condition but without applying the cathodic current. In addition, the corrosion resistance of the magnesium alloy was strongly improved after application of the Ni–P coating via the EPEP technique which was revealed by the EIS and Potentiodynamic Polarization (PDP) examinations in 3.5 wt. % NaCl corrosive media. Thickness, micro-hardness, porosity, and adhesion of the Ni–P coating obtained via the EPEP technique were also evaluated using appropriate methods.

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