Z. Sadeghian, R. Dezfulizadeh,
Volume 13, Issue 2 (June 2016)
Abstract
In situ Al2024- Mg2Si composite was fabricated by spark plasma sintering (SPS) of reactive powder. Reactive powder was obtained from mechanical alloying (MA) of elemental powders. Clad layers of in situ composite were fabricated on Al substrates by spark plasma sintering (SPS). Structural evolution during MA process and after SPS was investigated by X-ray diffractometery (XRD). Scanning electron microscopy (SEM) was utilized to study the microstructure of sintered samples. Hardness and tensile behavior of sintered samples were investigated. The results showed that SPS of mechanically alloyed unreacted powder can result in the in situ formation of Mg2Si and Mg2Al3 within the Al matrix. SPSed clad layer showed a sound and clear interface to the Al substrate with a hardness of about 140 HV. Sintered in situ composite exhibited a tensile strength of 288 MPa.
Saba Payrazm, Saeid Baghshahi, Zahra Sadeghian, Amirtaymour Aliabadizadeh,
Volume 19, Issue 3 (September 2022)
Abstract
In this research, zinc oxide quantum dots and graphene nanocomposites were synthesized via two different methods; In the first (direct) method, ZnO-graphene Nanocomposites were made mixing the synthesized zinc oxide and graphene. In the second (indirect) method, zinc nitrate, graphene, and sodium hydroxide were used to made ZnO-graphene Nanocomposites. XRD, FTIR and Raman spectroscopy analyses were used for phase and structural evaluations. The morphology of the nanocomposites w::as char::acterized by SEM. The specific surface area and porosity of the samples were characterized by BET analysis. The optical properties of the samples were investigated by photoluminescence and ultraviolet-visible spectroscopy analyses. Results showed that using graphene, increased the photoluminescence property and shifted the photoluminescence spectrum of the composites towards the visible light spectrum. The photoluminescence of the synthesized graphene-zinc oxide composite, in the visible light region, was closer to white light than that of pure zinc oxide. According to the results of BET test, the nanocomposite synthesized by direct method had a higher surface area (25.7 m2.g-1) and a higher porosity (0.32 cm3.g-1) than the nanocomposite synthesized by the indirect method with a specific surface area of (16.5 m2.g-1) and a porosity of 0.23 cm3.g-1).
Seyed Ehsan Khadempir, Behnam Lotfi, Zohreh Sadeghian,
Volume 21, Issue 0 (IN PRESS 2024)
Abstract
Ni-B4C nanocomposite coatings were deposited onto a pure Cu substrate using electroplating. Different types of current, including direct current (DC), pulse reverse current (PRC), and unipolar pulse current (PC), were applied using various concentrations of micron and nano size particles in the electroplating bath. Microstructure, hardness, and wear and corrosion behavior of the coatings were investigated. Microstructural evaluations were performed using scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM). Microhardness, pin-on-disk sliding wear, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) tests were conducted on the coatings. Electrodeposition using PRC resulted in a more uniform distribution of co-deposited B4C microparticles and nanoparticles within the coatings. Nanocomposite coatings reinforced with B4C nanoparticles were obtained using PRC with a bath concentration of 8 g/l, exhibited higher hardness and improved wear properties compared to composite coatings containing B4C micron-sized particles. Moreover, using PRC resulted in higher hardness values and improved wear and corrosion resistance compared to PC and DC.
