Showing 3 results for J. Vahdati Khaki
S.h.r. Fatemi Nayeri, J. Vahdati Khaki, M. R. Aboutalebi,
Volume 6, Issue 1 (winter 2009 2009)
Abstract
Abstract:A combination of mechanical activation and Differential Thermal Analysis (DTA) together with X-Ray
Diffraction (XRD), and various microstractural characterization techniques were used to evaluate the starting reaction
in the combustion synthesis of TiC-Al2O3 composite in TiO2-Al-C system. The mechanical activation was performed
on the mixtures of two components of TiO2/Al, Al/C and TiO2/C and then the third component was added according
to the stoichiometric reaction for 3TiC+2Al2O3 composite formation. The powder mixtures were heated up to 1450 °C
under Argon atmosphere at a heating rate of 10 °C/min. The combustion synthesis temperature was observed to
decrease from 962 °C to 649 °C after milling of TiO2/Al mixture for 16 hr. On the contrary, the mechanical activation
of Al/C and TiO2/C mixtures for 16 hr made the reaction temperature increase to 995 °C and 1024 °C, respectively.
The decrease in reaction temperature as a result of milling the TiO2/Al mixture could be due to an increase of TiO2
and Al interface area as confirmed by TEM micrographs and XRD patterns of milled powder mixture. In addition, DTA
experiments showed that for the sample in which TiO2 and Al were mechanically activated the reaction occurred at
the temperature even lower than that of Al melting point.
A. H. Emami, M. Sh. Bafghi, J. Vahdati Khaki, A. Zakeri,
Volume 6, Issue 2 (Spring 2009 2009)
Abstract
Abstract:
the changes of BET surface area of a mineral substance during intensive grinding process. Validity of the proposed
model was tested by the experiments performed using a natural chalcopyrite mineral as well as the published data. It
was shown that the model can predict the experimental results with a very good accuracy and can be used to predict
what may happen under the similar experimental conditions.
Based on experimental observations, a model has been developed to describe the effect of grinding time on
M.sh. Bafghi, A.h. Emami, A. Zakeri, J. Vahdati Khaki,
Volume 7, Issue 2 (Spring 2010 2010)
Abstract
Abstract:
has been investigated. It has been shown that the mechanism of leaching reaction is diffusion through the product layer
and does not undergo any change as a result of mechanical activation in a wide range of experimental conditions.
Leaching rate is strongly influenced by milling intensity and the effect of ball to powder mass ratio is stronger than
milling time. Curve fitting of experimental data shows that leaching rate constant is approximately a linear function
of ball to powder mass ratio, while it obeys a power function with regard to the milling time.
The kinetics of chalcopyrite leaching in a ferric sulfate media for raw and mechanically activated samples
