Reduction process of Cu/Sn nanocomposite by plasma furnace

Pre-milled copper and tin powder was subjected to heat treatment to investigate the effect of polyethylene glycol surfactant powder on it. The existing thermographic shows that the delta value of the copper-tin phase powder formation reaction is much higher than other chemical reactions, and this increase in energy is related to the new phase formation. Results of the DTA heat test in the direction of temperatures 300, 600, and 1000 °C were selected for this heat treatment and after that non-destructive and mechanical tests were performed on it, the phases Copper and tin are formed with great intensity and the particle size is reduced to 5 µm. On the other hand, the hardness of the resulting powder is greatly increased and about 220 HV0.1, all of which are due to the effects of adding a surfactant to copper and tin powder and ceramic phase made in this alloy.Peer ReviewedPreprin

Fundamental analysis of liquid breakup mechanism in a rotary atomizer with square discharge orifice

[EN] An experimental investigation of breakup mechanism in a rotary atomizer with square shape discharge orifice at ambient condition has been performed. The effects of a high aspect ratio noncircular discharge channels, particularly a square shape discharge channel, are considered. The motivation of this study is the use of this type of orifice in some small gas turbine engines as well as non-existing observation in literature concerning about high aspect ratio of discharge channel. Visualization experiments are conducted by high speed shadowgraph imaging technique with pulsed light illumination for the first time. The effects of rotational speed and volume flow rate are studied on the breakup structure. The visualizations indicates that the liquid film formed along the channel is pushed to one side of it due to Coriolis force which is dominant in this type of atomizer. Accordingly a crescent shaped liquid film is formed at the square channel exit covering two corners of the square, resulting the combination of Coriolis induced stream mode and surface tension induced stream mode breakup. Observations of the breakup process for different volume flow rates and rotational speeds indicate that the breakup of liquid film stream is dependent on injection conditions and the corresponding cross flow velocity created by atomizer rotation. The breakup regime map is provided as a function of weber number and momentum flux ratio. Four distinct regimes are identified: Rayleigh breakup, bag breakup, multimode breakup, and shear breakup. The present results leads to understanding atomization performance and creating some idea to improved spray quality in this type of atomizer.Ghorbanhoseini, M.; Rezayat, S.; Farshchi, M. (2017). Fundamental analysis of liquid breakup mechanism in a rotary atomizer with square discharge orifice. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 496-503. https://doi.org/10.4995/ILASS2017.2017.5640OCS49650

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

Modification of as-cast Al-Mg/B4C composite by addition of Zr

Zirconium was used in Al-Mg/B4C composite to improve compocasting efficiency by increasing particle incorporation. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) results revealed that by addition of zirconium a reaction layer containing Zr, Al, B and C is formed on the interface of B4C-matrix. X-ray diffraction (XRD) analysis of extracted particles unveiled that the ZrB2 phase is the main constituent of this layer. Formation of ZrB2 is an exothermic reaction which can rise temperature locally around particles and agglomerates. Rising temperature around agglomerates in conjunction with turbulent flow of melt facilitates agglomerates wetting and dissolving into molten aluminum. As the result, final product contains more uniformly distributed B4C particles. Besides enhancing compocasting efficiency, addition of Zr and formation of reaction layer by improving particle matrix bonding quality, led to increase in ultimate tensile strength and elongation of the composite around 8% and 30%, respectively. SEM observations of the fracture surfaces confirmed that a proper bonding presents at the interface of particles and matrix in presence of Zr.Peer ReviewedPostprint (author's final draft

Characterization and optimization of Cu-Al2O3 nanocomposites synthesized via high energy planetary milling: a morphological and structural study

This study examines the synthesis and characterization of a copper–alumina nanocomposite powder. Mechanical milling is employed to synthesize the powder, and a holistic analysis is conducted to evaluate its morphological and structural properties. TEM analysis reveals the presence of alumina particles within the copper matrix, indicating the formation of both coarse and fine particles at different stages of synthesis. XRD analysis demonstrates a reduction in copper’s crystallite size with increasing milling time, attributed to defects generated within the crystal lattice during milling. Additionally, statistical analysis is utilized to determine the significance of different factors influencing the synthesis process. ANOVA analysis reveals that milling time has a significant impact on the particle size of the nanocomposite powder, while temperature and their interaction do not exhibit significant effects. Optimization techniques are utilized to identify solutions that meet the specified constraints for milling time, temperature, particle size, and differential thermal response, resulting in favorable solutions within the desired ranges. The study highlights the efficacy of mechanical milling for producing nanocomposite powders with enhanced mechanical properties, offering promising prospects for advanced materials in various industries. Additionally, the characterization results provide valuable insights into the microstructure and phase distribution of the nanocomposite powder. The application of the Williamson–Hall method proves to be effective in determining the crystallite size of the synthesized powder.Peer ReviewedPostprint (published version

Texture development during hot deformation of an Al/Mg alloy reinforced with ceramic particles

Al-3Mg alloy reinforced with B4C particles in volume fractions of 5, 10 and 15% were subjected to hot deformation to investigate the impact of presence of ceramic particles and deformation condition on final texture. Single-heat hot compression test was performed at temperatures of 300–500¿°C with strain rates of 10-3 to 10 s-1. The electron backscatter diffraction method was applied to evaluate the final texture and microstructures. It was observed that the {110} fiber formed during deformation was intensified by increasing the Zenner-Holloman parameter, while deformation at lower Z makes {100} fiber pervasive throughout the matrix. Developing {100} fiber in such condition leads to continual softening of flow stress. Presence of particles by promoting particle stimulating nucleation mechanism at high Z and restricting grains rotation at low Z led to lower final texture intensity.Peer ReviewedPostprint (author's final draft

Accumulative roll bonding of aluminum/stainless steel sheets

An Al/Stainless Steel/Al lamellar composite was produced by roll bonding of the starting sheets at 400 °C. Afterward, the roll bonded sheet was cut in half and the accumulative roll bonding (ARB) process at room temperature was applied seven times. As a result, the central steel layer fractured and distributed in the Al matrix among different layers introduced by the repetition of roll bonding process. The tensile results showed that the roll bonded sheet has much higher strength and strength to weight ratio compared with the initial aluminum sheet as a result of the presence of continuous steel core. However, poor ductility properties were observed during tensile test, which were ascribed to the increasing deformation resistance and localized thinning of the central stainless steel sheet during the roll bonding process. The ARBed sample exhibited lower strength compared with the roll bonded sheet due to the breakup of stainless steel layer into many small segments. Anyway, an ultrafine grained microstructure with average grain size of 400 nm in the aluminum matrix and 71% strain-induced martensite in the steel segments were detected by the electron backscattered diffraction (EBSD) technique, which were found to be responsible for the enhancement of mechanical properties compared with the initial aluminum sheet.Peer ReviewedPostprint (published version

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

Exploring the effects of laser surface modification on AISI 301LN steel: a micro-mechanical study

This article investigates the surface hardening capability of a metastable austenitic TRansformation Induced Plasticity (TRIP) stainless steel, particularly on AISI 301LN, by laser texturing. This technology produces microstructural surface changes in terms of both phase transformation and grain size modification and, as a direct consequence, the laser influences the surface characteristics, mainly hardness and roughness. In this sense, the key parameters (laser power, scanning speed and position of the focal length) were investigated by using a Design of Experiments (DoE) in detail to better understand the correlation between texturing parameters, microstructural and mechanical changes, always at the superficial level. From all the aforementioned information, the results show that the maximum surface hardening is obtained by increasing the laser power and decreasing the scanning speed. Furthermore, by reducing the focal distance, the depth of the microstructural evolution layer is more significant, while the width is less affected. Finally, a suitable model was developed to correlate the processing parameters here investigated with the resulting surface integrity, in terms of mechanical properties, by means of a regression equation.This research was funded by AGAUR, Agency for Administration of University and Research (Agència de Gestió d’Ajuts Universitaris i de Recerca), grant number FI-SDUR 2020.Peer ReviewedPostprint (published version

Influence of Aluminum and Copper on Mechanical Properties of Biocompatible Ti-Mo Alloys:A Simulation-Based Investigation

The use of titanium and titanium-based alloys in the human body due to their resistance to corrosion, implant ology and dentistry has led to significant progress in promoting new technologies. Regarding their excellent mechanical, physical and biological performance, new titanium alloys with non-toxic elements and long-term performance in the human body are described today. The main compositions of Ti-based alloys and properties comparable to existing classical alloys (C.P. TI, Ti-6Al-4V, Co-Cr-Mo, etc.) are used for medical applications. The addition of non-toxic elements such as Mo, Cu, Si, Zr and Mn also provides benefits, such as reducing the modulus of elasticity, increasing corrosion resistance and improving biocompatibility. In the present study, when choosing Ti-9Mo alloy, aluminum and copper (Cu) elements were added to it. These two alloys were chosen because one element is considered a favorable element for the body (copper) and the other element is harmful to the body (aluminum). By adding the copper alloy element to the Ti-9Mo alloy, the elastic modulus decreases to a minimum value of 97 GPa, and the aluminum alloy element increases the elastic modulus up to 118 GPa. Due to their similar properties, Ti-Mo-Cu alloys are found to be a good optional alloy to use.Peer ReviewedPostprint (published version