Category Archives: General

Electrochemical deposition and characterization of nanocrystalline Fe-Ni coatings

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Fig.1: Variation of metal contents in the deposit with applied c.d.

Nanocrystalline Fe-Ni coatings were electrodeposited on mild steel (MS) panels at different current densities (c.d.) from an acid sulphate electrolyte. The operating parameters were optimized for best appearance and performance of the coatings. Different techniques like Field Emission Gun Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray Analysis (EDXA), X-Ray Diffraction, potentiodynamic polarization scan and Electrochemical Impedance Spectroscopy (EIS) were employed to characterize the electrodeposited thin films. The electrodeposition process was found to be anomalous with 35% to 70% Fe, depending on the current densities (c.d.) employed for deposition. The properties of all coatings were found to show close dependency with c.d., phase structure and composition of the alloys. Corrosion behaviors were studied in 5% HCl and 5% KOH medium and corrosion parameters were reported. Experimental results are discussed by relating the composition, phase structure and grain size with corrosion performance of the coatings in both acid and alkaline medium.

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Effect of magnetic field on current efficiency and crystal orientation of NiCo alloy using pulse electrodeposition technique

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Fig. 1: Electrodeposition process setup

The electrodeposition of NiCo alloy has been investigated in presence of various magnetic fields. The influence of superimposed magnetic field (0-0.5T) parallel to the electrode surface on current efficiency, surface morphology, preferred crystal orientation and electrochemical activity of Ni-Co alloy were studied. The maximum current efficiency was obtained by direct current at 100mA/cm2 with 0.4T. The optimized current density (100mA/cm2) was pulsed at four different frequencies (10, 25, 50 and 100Hz) with the same magnetic field (0.4T). However, the superimposition of magnetic field significantly favors the preferred crystal orientation of (220) phase. Pulsed current deposits exhibit single orientation of (220) at lower magnetic field (0.4T) whereas direct current deposition require higher magnetic field (0.5T). Tafel plot shows that electro-catalytic activity and corrosion resistance property has improved when the deposit is having a preferred orientation of (220).

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A new insight into the phosphorus distribution of nanocrystalline Ni-Ni3P-diamond composites

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The microstructure of an electroplated Ni-Ni3P-diamond composite has been studied by field-emission scanning electron microscopy, energy dispersive X-ray spectrometry and transmission Kikuchi diffraction. The use of an electron transparent sample reduced the resolution limits of X-ray spectrometry and electron backscatter diffraction. Basing on the P distribution and Ni/Ni3P orientation maps, standard observations made by backscattered electron imaging can be easily interpreted.

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Electroless Deposition of Palladium – Part 2

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In Part 1 of this series on the electroless deposition of palladium, the properties of the metal itself were discussed as well as the benefits of the electroless deposition process. In Part 2, the autocatalytic position processes are detailed with an exhaustive review of previously published work in this area.

Link: Electroless Deposition of Palladium – Part 1

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Electroless Deposition of Palladium – Part 1

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Palladium is an interesting element in surface chemistry. It is a noble metal and an active catalyst in many  reactions. Palladium or palladium alloys are used in the fields of catalysts, electronics or hydrogen seperation or purification. One special application is its use as a catalyst for metallising non-conductors like platic materials. In this paper the literature concerning the deposition of catalytic palladium for the surface activation prior to the deposition of electroless nickel and other metals is reviewed.

Link: Electroless Deposition of Palladium – Part 2

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