P. Samadi, M. Reza Afshar, M. R. Aboutalebi, S. H. Seyedein,
Volume 9, Issue 1 (march 2012 2012)
Abstract
Electrochemical coating processes are significantly affected by applied magnetic fields due to the generation of electromagnetic forces. The present research work has been undertaken to study the effect of coating parameters such as current density and alumina concentration on the characteristics of Ni-Al2O3 composite coating under static magnetic field. Ni-Al2O3 composite coating was applied on a mild steel substrate using conventional Watts solution containing Al2O3 particles with and without magnetic field. The coating microstructure and Al2O3 particle density in the coating layer were examined by scanning electron microscopy (SEM). It was found that the applied magnetic field made the coating structure finer and leads to the increases of the particle content in the coating. However, the results confirmed that the magnetic forces inversely affected the particle density in the coating at higher current density than that of normal coating process.
M. Heydari Nasab, R. Naghizadeh, H. Samadi, A. Nemati,
Volume 12, Issue 1 (march 2015 2015)
Abstract
Ceramic-matrix composites containing TiC-TiN have been used in a variety of application because of their
superior properties such as high hardness, good wear resistance and high chemical stability. In this research, effect of
coke and coke/calcium beds in synthesis of Al
2O3-Ti(C, N) composites using alumino-carbothermic reduction of TiO
2
has been investigated. Al, TiO
2
and active carbon with additives of extra carbon and NaCl and without additives, in
separate procedures, have been mixed. Afterwards, mixtures were pressed and synthesized in 1200oC for 4hrs, in coke
and coke/calcium beds, separately. Al
2O3-Ti(C,N) composite was synthesized in ternary system of Al-TiO
2
-C with
excess carbon and NaCl additives in calcium/coke bed in 1200 . X-ray diffraction patterns (XRD) results showed that
existence of calcium in bed resulted in intensification of reduction atmosphere in samples and formation of Ti(C,N)
phase enriched from carbon was accelerated. Crystallite sizes of synthesis Ti(C,N) at 1200 °C in reducing conditions
were 22-28 nm.
