Saeed Reza Allahkaram

Effects of Direct Current and Pulse Electrodeposition Parameters on the Properties of Nano Cobalt Coatings

The aim of this study was to investigate the effects of direct current (DC) and pulse current (PC) parameters on the properties of cobalt (Co) coatings electrodeposited from a chloride acidic bath. The effects of peak current density, frequency and duty cycle on the surface morphology, crystal size, thickness, current efficiency, and preferred orientation of the deposits were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The experimental thickness of the deposit was lower for pulse plating compared to that of DC plating. The current efficiency was comparatively higher for pulse plating. Less porosity and fine grains were formed by pulse plating. From XRD analysis, the calculated grain sizes of nano and micro Co coatings were around 65nm and 430nm, respectively. The results showed that, with an increase in duty cycle, grain sizes would increase, too. As pulse frequency was increased to 50Hz, grain sizes would also decrease. However, at higher frequencies, grain sizes would increase again.

Preparation and characterization of durable micro/nanocapsules for use in self-healing anticorrosive coatings

In the field of coatings, extensive laboratory research has been conducted in the last decade. In the present work, effectiveness of epoxy resin filled micro/nanocapsules was investigated for future using in healing of cracks generated in coatings. Micro/nanocapsules were prepared by in situ polymerization of urea–formaldehyde resin to form shell over epoxy resin droplets. The optimal process parameters for synthesizing the micro/nanocapsules were selected. The as-synthesized capsules were studied by various characterizations techniques, including scanning electron microscope (SEM), particle size analyzer (PSA), Fourier transform-infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results indicate that micro/nanocapsules containing epoxy resins can be synthesized successfully. The rough outer surface of microcapsule is composed of agglomerated urea–formaldehyde nanoparticles. They basically exhibit good storage stability at room temperature, and they are chemically stable before the heating temperature is up to approximately 250°C.

Characteristics and properties of Cu/nano-SiC and Cu/nano-SiC/graphite hybrid composite coatings produced by pulse electrodeposition technique

ABSTRACT In this study, Cu/SiC and Cu/SiC/graphite nano-composite coatings were prepared by using pulse current electrodeposition technique. The effects of pulse parameters and graphite particles concentration of the bath on co-deposition of these particles were investigated. Morphology, composition, structure, microhardness, tribological behaviour and corrosion properties of Cu/SiC/graphite coatings were studied and compared to those of the substrate and Cu/SiC films. The results revealed that the optimum current density, pulse frequency and duty cycle for obtaining the highest graphite content within the coatings were 12 A dm−2, 15 Hz and 5%, respectively. According to X-ray diffraction results, all the coatings had face-centred cubic structure, but with different preferred orientations. While Cu/SiC coatings had higher hardness and corrosion resistance than the Cu/SiC/graphite hybrid composites, the lowest wear rate was obtained at Cu/6.8vol.-% SiC/6.7vol.-% graphite hybrid composite film.

Calculating of the Relative Preference of Criteria Affecting Electroless Coating of Alumina Nano Particles on Ni-B by Analytic Hierarchy Process (AHP) Method

In metallurgical engineering, there are different criteria affected on coating on surface of the material such as physical, chemical, mechanical, electrical and economical properties. In this study, using the Analytic Hierarchy Process (AHP) to calculation the performance of criteria for priority by addition of different concentration alumina (Al2O3)nanoparticles in Electrolyte and heat treatment on substrate nickel-borne electroless method has been calculated. The alumina particles with an average grain size of 50nm in different concentrations were added to a solution electroless Ni-B plating which were coated on conventional steel sample. The AHP determined that the most favorable concentration of alumina particles is 1gr/lit .

Evaluation of Corrosion Properties of Electroless NiP/Nano-SiC Composite Coatings

Ni-P/nano- SiC composite coatings were deposited in different concentrations of SiC nano-particles in the bath. The hardness and corrosion resistance of the composite coatings with different content of SiC nano-particles were measured. Moreover, the structure of the composite coatings was investigated by means of X-ray diffraction (XRD), while their morphologies and elemental composition were analyzed using scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS). Results showed that co-deposited SiC nano-particles contributed to increase the hardness but corrosion resistance of electroless Ni-P coatings decreased due to agglomeration of nano-particles and increasing porosity of coatings.