Showing 3 results for Shokuhfar
A. Shokuhfar, S. Ahmadi, H. Arabi, S. Nouri,
Volume 6, Issue 3 (Summer 2009 2009)
Abstract
Abstract: Guinier-Preston (GP) zone formation and precipitation behavior of T1 (Al2CuLi) phase during the ageingof an Al-Cu-Li-Zr alloy was studied by differential scanning calorimetry (DSC) technique and electrical resistancemeasurement of the samples. Results show that endothermic effects in the thermograms of the alloy between 180°Cand 240°C can be related to the enthalpy of GPzones dissolution. Formation of GPzones in the structure increasedhardness, tensile strength and electrical resistance of the Al-Cu-Li-Zr alloy. Furthermore, precipitation of T1 phaseoccurred in temperature range of 250ºC to 300ºC whereas its dissolution occurred within the temperature of 450-530ºC. Activation energies for precipitation and dissolution of T1 phase which were determined for the first time inthis research, were 122.1(kJ/mol) and 130.3(kJ/mol) respectively. Results of electrical resistance measurementsshowed that an increase in the aging time resulted in the reduction of electrical resistance of the aged samples.
M. Alzamani, A. Shokuhfar, E. Eghdam, S. Mastal,
Volume 10, Issue 1 (march 2013)
Abstract
Abstract:In the present research, SiO2–TiO2 nanostructure films were successfully prepared on windshields using the sol–gel technique for photocatalytic applications. To prevent the thermal diffusion of the sodium ions from the glass to TiO2 films, the SiO2 layer was pre-coated on the glass by the sol–gel method. The substrates were dipped in the sol and withdrawn with the speed of 6cm/min-1 to make a gel coating film. The coated films were dried for 2 days at 27 °C to allow slow solvent evaporation and condensation reactions due to rapid sol–gel reaction of Titania precursor. Then, the films were annealed at 100 °C for 30min and at the final temperature (500, 700 °C) for 30 min continuously. The structure and surface morphology properties, which are as a function of annealing temperature, have been studied by SEM FE-SEM and XRD. The FE-SEM surface morphology results indicate that the particle size increases from 19 to 42 nm by increasing the annealing temperature from 500 °C to 700 °C. Likewise, XRD illustrate the crystal anatase and rutile as main phases for TiO2-SiO2 films annealed at 500 °C and 700 °C respectively. This procedure resulted in transparent, crack-free SiO2–TiO2 films.
A. Ostovari Moghaddam, A. Shokuhfar, A. Cabot,
Volume 16, Issue 4 (December 2019)
Abstract
Metal sulfides containing non-toxic and earth abundant elements have emerged as new environmentally friendly thermoelectric materials. In the present work, a new, fast and large scale route to synthesise bulk nanostructured Co1-xCuxSbS paracostibite is presented. Stoichiometric compositions of Co1-xCuxSbS nanoparticles with 0 ≤ x ≤ 0.08 were first processed by high energy ball milling for 3 h, and then annealed at different temperatures between 400 ºC to 650 ºC for 1 h. The phase transitions and diffusion process during annealing were thoroughly studied by x-ray diffraction (XRD) and scanning electron microscopy (SEM). Agglomerated nanoparticles with sizes in the range from 40 nm to 80 nm were obtained after 3 h of ball milling, and remained below 100 nm after annealing and hot pressing. The thermoelectric properties of hot pressed samples, including the Seebeck coefficient (S), electrical conductivity (σ) and thermal conductivity (k), were measured from room temperature up to 723 K. All the samples exhibited a p-type semiconductor character at room temperature and underwent a transition from p-type to n-type conduction above 473 K. a maximum ZT value of 0.12 was obtained for Co0.06Cu0.04SbS4 at 723 K.
