ElectroCatalytic Activity of Nickel Foam with Co, Mo, and Ni Phosphide Nanostructures

In this study, the electrocatalytic activity of nickel foam, which is activated by cobalt, molybdenum, and nickel phosphide nanostructures, is prepared by the plasma hydrothermal method for use in the release of hydrogen and oxygen. The morphology and crystallographic structure of the synthesized phosphide specimens were examined by means of scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction. Moreover, the electrolysis activity for these sets of specimens was investigated using the Tafel polarization curve or linear sweep voltammetry, cyclic voltammetry, as well as by means of the electrochemical impedance spectroscopy technique. Preliminary results show that nickel phosphide presents the highest electrocatalytic activity than the other phosphides developed in this research. In this regard, it presents an electrocatalytic activity to release hydrogen and oxygen of around -1.7 and 0.82 mV, which is measured at a current density of 100 mA·cm-2, respectively.Peer ReviewedPostprint (published version

Mechano-chemical activation of MoO3-CuO/C powder mixture to synthesis nano crystalline Mo-Cu alloy

In this study, a high energy planetary ball milling technique was used to synthesize nano-crystalline Mo-Cu alloys. Molybdenum trioxide (MoO3) and copper oxide (CuO) were used as the starting materials. Carbo-thermal co-reduction of mixed Mo and Cu oxides powders was done with milling followed by a heat treatment at a high temperature. Differential thermal analysis/thermogravimetric (DTA/TG) was used to determine the heat treatment temperature of activated powders. X-ray diffraction (XRD) analysis was used to investigate the phase structure during the milling and heat treatment. Field emission scanning electron microscopy (FESEM) has been employed to investigate the morphology of powder particles. It was found that the complete carbo-thermal reduction of the oxides mixture may not be possible by the mechanical milling at the ambient temperature and based on thermodynamic investigations, thermal activation was necessary to reduce a MoO3-CuO mixture to a metallic structure. Some peaks at 400, 600 and 950 °C from DTG results of the mixture sample milled for 10 h were observed which were related to the Cu6Mo5O18, MoO2-Cu and Mo formation during carbo-thermal reduction of the MoO3-CuO mixture, respectively. XRD results showed 10 h milled sample after reduction at 1000 °C contained nano-crystalline Mo-Cu alloys with a mean crystallite size of 42 nm for Mo and 37 nm for Cu calculated by the Scherrer equation

Tribological and corrosion performance of electrodeposited Ni-Fe/Al2O3 coating

Nickel–Iron coating was formed from a sulfate base electroplating bath under a current density of 3 A/dm 2 and turbulence of 300 rpm on a previously prepared cylindrical steel substrate. In order to obtain a sample including nickel composite coating, different amounts of alumina particle powder were added to the plating solution of the sample in question. By adding different quantities of ferrous sulfate to the electroplating bath under a current density of 2.5 A/dm 2 and turbulence of 300 rpm, an optimal sample containing 20 g/L of ferrous sulfate was obtained was free of any stress and microcracks. A hardness test was performed for the optimal sample among the nickel–iron¿ composite samples, and the sample containing 50 g/L of alumina particles was selected as the optimal sample. The Ni–Fe/Al 2O3 composite sample was tested for hardness, corrosion and wear. The obtained results showed that the highest hardness level is equivalent to 740 HV and the best corrosion resistance with the most positive corrosion potential. The lowest amount of wear mass is equal to 0.1 mg, and it showed the highest wear resistance.Peer ReviewedPostprint (published version

Effect of processing parameters on the mechano-chemical synthesis of nano crystalline Mo-Cu/Al2O3 composite

In this study, molybdenum-copper/alumina nano composite was synthesized with mechano-chemical method using high energy planetary ball milling. The molybdenum oxide, copper oxide and aluminum powder were used as starting materials and reaction appeared to occur through a rapid combustion reaction process. The evaluation of powder particles after different milling times was studied by X-ray diffraction (XRD), differential thermal analysis/thermogravimetric (DTA/TG) and scanning electron microscopy (SEM). XRD results show that with increasing milling time at ambient temperature the peak intensities of powders decreases and significant peak broadening due to decrease in the size of crystallites observed. As a result, after 100 h milling time a molybdenum-copper/alumina metal matrix nanocomposite was formed which matrix had a crystallite size of about 42  nm for cu, calculated from Williamson-Hall equation. In fact by increasing the milling time after reduction of metal oxides, molybdenum dissolves in copper matrix and supersaturated Cu(Mo) solid solution with a homogenous distribution of nano-sized Al2O3 as reinforcement materials was formed. The thermal analysis curves of 10 minutes milled sample shows some peaks related to reduction of copper and molybdenum oxide with aluminum. In addition the small endothermic peak at 650 °C observed from DTA curve is due to the melting of remaining Al

Effect of lateral laser-cladding process on the corrosion performance of Inconel 625

This study aimed to evaluate the corrosion properties of different samples coated by the laser-cladding method to find the optimal laser parameters. Thereby, potentiodynamic polarization (Tafel) and electrochemical impedance tests were performed to assess the corrosion resistance of coated samples. Consequently, the corrosion morphology of tested samples was inspected by scanning electron microscopy. The results demonstrated that the laser power directly correlates with pitting corrosion and defects on the surface of the samples. Moreover, when molybdenum and chromium ions are increased in the electrolyte solution, the passive and protective layers are more durable, as the ions are sited within the holes and defects, reducing the surface corrosion rate.Peer ReviewedPostprint (published version

Bactericidal properties of copper-Tin nanoparticles on Escherichia coli in a liquid environment

In this research, copper-tin alloy nanoparticles were made by a mechanical alloying method and were examined by two well-known and common bactericidal tests, optical density, and colony-forming units count in terms of bactericidal properties. To confirm the results, two different percentages were used as Sn-50Cu and Sn-83Cu, and standard amounts of these alloys were added to the Escherichia coli bacterial culture medium. The results of optical density show that with the addition of more values to the culture medium for bacteria, witnessing the destruction of bacteria, and also the results of colony counting tests can be seen that the number of colonies has decreased over time, even close to zero, which means the environment is free of bacteria. These standard values were different for both alloys; for the Sn-50Cu alloy, the maximum value was 4.5 mg, and for the Sn-83Cu alloy, it was 2.75 mg, which did not make any difference with the addition of these nanoparticles to the bacterial culture mediumPeer ReviewedPostprint (published version

Statistical analysis of experimental factors for synthesis of copper oxide and tin oxide for antibacterial applications

This research explores the impact of Cu composition, heating temperature, and milling time on the production of copper-tin alloy nanoparticles. By employing design of experiments techniques, the study systematically evaluates these input variables and their effects on particle size, optical density, and number of colonies. The identification of new Cu3Sn phases in the nanoparticle structure contributes to the novelty of this research. The findings highlight the potential for optimizing copper-tin alloy nanoparticle synthesis and enhancing their antibacterial properties. Mechanical alloying is found to produce nanoparticles up to 15 nm in size. Increasing the percentage of copper leads to improved antibacterial properties. This work provides insights into the synthesis process of copper-tin mechanical alloying and their potential for antibacterial applications.Peer ReviewedPostprint (published version