Journal of advanced materials and processing
Volume:7 Issue: 4, Autumn 2019

Current efficiency and energy consumption are two important factors in sodium ferrate synthesis. In this article, sodium ferrate was produced by the electrochemical method and the effects of different synthesized parameters such as applied current density, sodium hydroxide concentration and temperature on current efficiency and energy consumption have been studied. Decomposition of sodium ferrate, anode passivation and deviations in anodic and cathodic reaction rates with time have been tested by weight loss test, potentiodynamic polarization, and UV-visible spectroscopy, respectively. Also, the impact of each one on current efficiency and its consequence on energy consumption rate were studied. The results showed that the optimum conditions were 3.94 mA/cm2, 16 M NaOH and 50 oC for applied current density, sodium hydroxide concentration, and temperature, respectively. In this situation, the current efficiency was calculated as 91.7% and the energy consumption reached 1.91 kW.h/kg. Keywords: Electrochemical method; Sodium ferrate; Alkaline solution; Current efficiency; Energy consumption.

The porous scaffold provides a temporary environment for bone growth and facilitates cell adhesion, cell growth and differentiation. In the present study, polymeric scaffolds were designed and fabricated via fused deposition modelling (FDM) method for orthopedic defect approaches using polycaprolactone (PCL) and polylactic acid (PLA) polymer. The prepared scaffold was coated with Chitosan-Hydroxyapatite (HA) as a reinforcement. The application of PLA, PCL and HA received attention of orthopedic surgeons to accelerate the bone healing. However, the comparison between the compression strength value of these scaffolds required more investigation and advance mechanical testing. In this study, we coat the novel PCL and PLA scaffold with chitosan-HA composite to mimic with humans' body. In the next stage, the mechanical strength and the biological response of the specimen were examined. Then, the morphology and phase characterization of the materials were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD) technique. The apatite formation and weight change test were performed on the porous scaffold which showed proper hydrophilicity. The microstructure of the porous scaffold was simulated using the Abaqus simulation with the extracted data from the experimental work. At the end, it was concluded that the most suitable scaffold was fabricated made of PLA filament and coated with chitosan-hydroxyapatite nanocomposite which can be useful choice for bone tissue engineering.

In this study, the corrosion rates for St37 carbon steel in some soil types with different conditions were measured. The effects of the parameters of moisture amount, soil’s particle size and salt’s concentration were determined by the mass loss method. An Artificial Neural Network (ANN) model with three inputs and one output was established to simulate the experimental data. It was observed that Levenberg–Marquardt algorithm with hyperbolic tangent sigmoid transfer function provided the best results in training with the lowest MSE and MAE compared to the other methods in the model. The R values for training, validation, and test were presented and the value of 0.98684 was achieved for the complete data set which demonstrate a high level of ANN performance. The Genetic Algorithm (GA) was also used to find optimum inputs for the target of minimum corrosion rate value. The results showed a good agreement between the model prediction and experimental values.

This study has investigated the synthesis of (Ti1-xWx)3SiC2 MAX phase via high energy ball milling, and the effect of heat treatment and excess Si on the purity of synthesized powder were explored. In this regards, different mixtures of Ti, Si, and C were ball milled by a planetary ball mill for various milling times up to 15h. The phase evolution of products was studied by X-ray diffraction (XRD), and the morphological changes monitored by a field emission scanning electron microscopy (FESEM) equipped with energy-dispersive spectroscopy (EDS). The results showed that after 15 hours of ball milling the reaction started, and resulted in Ti3SiC2 and TiC formation. The as-synthesized powders were then compacted and heat treated at 600, 1000, 1250 and 1400˚C. Heat treatment caused to proceed in the reaction between the intermetallic compounds in Si-Ti system and TiC, and led to increasing the purity of Ti3SiC2. In a separate run, a non-stoichiometric composition of Ti: Si:C= 3:1.2:2 was ball milled for 15 h, and heat treated at 1250˚C. The XRD results showed that the purity of the product is higher than the stoichiometric composition. The addition of W to Ti3SiC2 was also explored. In this regard, the synthesis of (Ti1-xWx)3SiC2 component (x= 0.8, 0.5) was investigated, and the results showed that some W incorporated in Ti3SiC2 structure, and the WC and TixW1-x formed during the process.

Chromium alloy steels are the best choice for materials used in interconnect plates used in solid oxide fuel cells. At operating temperature of solid oxide fuel cells chromium can alert to unstable Cr+6 species. These unstable species can precipitate at the cathode site, causing cathode contamination and reducing cathode efficiency. Therefore, protection of these steels at high temperatures is essential. Therefore, applying surface coatings it is one of the best effective methods to extend the life of these components against oxidation. In this study, Ni-Co-CeO2 composite coating was created by direct electrodeposition on the surface of AISI 430 ferritic stainless steel. In order to obtain proper coating, the effect of parameters of CeO2 particle concentration, current density and pH in the bath was investigated. Influence of CeO2 content (5, 10, 15 and 20 g/L), current density (15, 17, 20 and 22 mA/cm2) and pH (2.5, 3, 3.5 and 4) on the amount of CeO2 ceramic particle deposition and microstructure of coating was investigated. Scanning electron microscopy (SEM) and EDX analysis were used to determine the morphology of Ni-Co-CeO2 composite coating. The results showed that with increasing CeO2 and pH the amount of CeO2 particle deposition increased and then decreased. Also with increasing current density the deposition of CeO2 particles decreased.

Among nanostructured materials, magnetic nanowires have been heeded because of their high shape anisotropy and their easy fabrication methods. Electrochemical deposition on the anodic aluminium oxide (AAO) is one of the best methods to grow different nanowires. In this paper, the AAO was fabricated on the 1100 Al alloy substrate by hard anodizing in 0.3 M oxalic acid solution. Then, barrier layer thinning process was carried out for electrodeposition process. Pulsed electrodeposition process was used to fill the nano-pores. According to this method, cobalt nanowires were grown in the nano-holes. Structural, crystalline and magnetic properties of the samples were evaluated using field emission scanning electron micr (FESEM), X-ray diffraction (XRD) and Vibrating Sample Magnetom (VSM) respectively. The results showed that nanowires have a diameter of 87 nm and crystalline structure with crystalline plates in directions (100), (002) and (110). A coercivity value of 600 Oe were obtained for nanowires, which is several times larger than cobalt bulk.