Showing 8 results for H. Sarpoolaky
B. Alinejad1,, H. Sarpoolaky1,, A. Beitollahi1, S. Afshar2,
Volume 4, Issue 1 (winter & spring 2007 2007)
Abstract
Abstract: Nanocrystalline MgAl2O4 spinel powder was synthesized using metal nitrates and a
polymer matrix-based composed of sucrose and polyvinyl alcohol (PVA). The precursor and the
calcined powders were characterized by simultaneous thermal analysis (STA), X-ray diffraction
(XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy
(SEM). According to XRD results, the inceptive formation temperature of spinel via this technique
was between 600°C and 700°C. The average crystallite size of calcined powder at 800°C for 2h
was in the range of 8-12nm. In addition, SEM micrograph showed that the synthesized powder had
a spherical morphology.
A. Ahmadi,, H. Sarpoolaky,, A. Mirhabibi, F. Golestani-Fard,
Volume 4, Issue 3 (Summer &Autumn 2007 2007)
Abstract
Abstract: Dolomite based refractories are widely used in Iranian steelmaking plants. In the
present research, wear and corrosion of refractories used in steel-making converter lining in
Esfahan Steel Company was studied. Post-mortem analysis of refractories clarified that the wear
started with oxidation of carbon followed by chemical corrosion. Iron oxide from slag reacted with
calcia, resulting in formation of low melting phase, and subsequent washout process, caused the
refractory corrosion onset from the hot face. In addition, the effect of aluminum as an anti-oxidant
and graphite on the corrosion resistance of refractory was investigated. Tar-dolomite samples
containing different amount of graphite (0, 4, 7, and 10 wt. %) were prepared in order to study
their physical properties, before and after coking. SEM micrographs employed to analyze the
microstructures to determine the effect of graphite and antioxidant on corrosion behavior of the
refractory. Results showed that oxidation process of carbon in the system was hindered and
improved corrosion resistance by introducing graphite and antioxidant into the refractory
composition.
M. Khosravi Saghezchi, H. Sarpoolaky, F. Heshmatpour,
Volume 5, Issue 2 (spring 2008 2008)
Abstract
Abstract: Lead-containing glass borosilicate was synthesized by Sol-gel technique using
metalalkoxids such as tetraethyleorthosilicate (TEOS), Al-sec-butoxide and trimethyl borate. The
sol containing TEOS converts to gel during drop wise addition of Al-alkoxide while inorganic lead
salt was added in the last stage of gelation to prepare the alcogels. The specimens were dried at
room temperature to set then heated at 600°C quickly to avoid crystallization preparing a glass
containing 63 wt% lead oxide. The influence of pH on absorption behavior of the sols studied by
UV visible technique so the characteristic of the gel, alcogel and xerogel were studied in the
different acidic concentrations. The UV spectrums show that the higher the acidity of the
hydrolysis stages, the higher the absorbance. The results showed the sample with 63 wt% lead was
found fully amorphous. Microstructure and phase analysis of the glass powders were investigated
by X-ray diffraction (XRD), X-ray fluorescence (XRF) and scanning electron microscopy (SEM)
equipped with EDS analysis.
N. Hamedani Golshan,, H. Sarpoolaky, A. R. Souri,
Volume 8, Issue 1 (winter 2011 2011)
Abstract
Abstract: Efforts have been carried out in order to use microsilica to develop a forsterite bond rather than other types of binders in the basic refractory castables. According to the higher drying rate and sinterability of colloidal silica, it has been proposed in the recent years. In the present work, effects of replacement of microsilica by colloidal silica evolution of forsterite bond have been studied in magnesia based refractory castables. In this way, Physical properties of prepared samples with different amount of colloidal silica versus temperature were investigated. In addition, phase variation and microstructural evolution of sintered specimens at 1000, 1200 and 1400 °C were studied by X-ray diffraction (XRD) and scanning electron microscope (SEM) respectively. Results showed that, due to Reaction of magnesia with microsilica and colloidal silica, magnesium hydrate and magnesium silicate hydrate formed in the dried samples strengthening the texture of the samples while forsterite formed from about 1000 °C and gradually increased with temperature rise. Also, better forsterite formation would be appeared by increasing the colloidal silica content. Further investigation carried out on the type of silica addition on properties of the castable refractory samples. It was found that the presence of micro silica and colloidal silica simultaneously (MS3C3 sample) at 1400 °C, caused modifying mechanical strength in compare with sample with only micro silica (MS sample).
F. Kashaninia, H. Sarpoolaky, A. R. Bagheri, R. Naghizadeh, M. Zamanipour,
Volume 8, Issue 4 (december 2011)
Abstract
Abstract: There have been lots of studies to control the poor hydration resistance of dolomite refractories one of the
most effective solutions has been the addition of magnesia to doloma. Using a co-clinker of magnesia-doloma as a
starting material would provide more homogeneity in the properties of the product and has been published recently.
On the other hand, addition of iron oxide to doloma has been found to increase the hydration resistance. In this paper,
the effect of iron oxide addition on hydration phase analysis and microstructure of two different magnesia- doloma
samples, one with CaO content of 25 wt% and the other one with that of 35 wt% has been investigated. Ten samples
were prepared by pressing followed by firing at 1750 ºC for 3hrs. Results showed that the hydration resistance of the
samples improved by decreasing the CaO content, because CaO is much more prone to hydration comparing to MgO.
Besides, iron oxide addition lead to the formation of iron-containing phases which increased the hydration resistance
of the samples both by capsulating the CaO and MgO grains and by promoting the liquid phase sintering.
H. Yaghoubi, H. Sarpoolaky, F. Golestanifard, A. Souri,
Volume 9, Issue 2 (june 2012 2012)
Abstract
Colloidal silica bonded refractory castables have been developed recently. It was found that colloidal silica is one of the best binders can substitute other binders such as cement in No Cement Castable (NCC) and Ultra Low Cement Castable (ULCC) refractories. Also composition of colloidal silica with appropriate additives resulted in a gel form which makes the initial strength. Moreover, the nano size silica particles are extremely reactive in high alumina castables and may encourage the mullite formation in the microstructure. In the current study, four castables were prepared. The sample containing 6wt % microsilica was a reference, then microsilica was replaced by different amount of colloidal silica (2.5, 5, 7.5 wt %). Silica and water content was kept constant. It’s concluded that the castables containing the optimum amount of silica sol shows remarkable increase in both castable fluidity and mechanical strength (CCS and MOR) in dried and sintered state. It was also found that nanosilica particles increase the rate of needle-shaped mullite formation during sintering at 1400°C. According to FTIR results, the addition of Calcium Aluminate Cement (CAC) to the silica sol may be responsible for the increment of siloxane bridges (Si-O-Si).
V. Tajer-Kajinebaf, H. Sarpoolaky, T. Mohammadi,
Volume 10, Issue 1 (march 2013)
Abstract
Abstract:Nanostructured titania was synthesized by colloidal and polymeric sol-gel routes. Stable colloidal and polymeric titania sols were prepared by adjusting the proper values of the acid/alkoxide and the water/alkoxide molar ratios. The properties of sols were determined by dynamic light scattering technique and synthesized titania was characterized by thermogravimetry and differential thermal analysis, X-ray diffraction, Fourier transform infrared spectroscopy, optical microscopy and field emission scanning electron microscopy. The results showed particle size distribution of colloidal sol 10-50 nm compared to polymeric one which was 0.5-2 nm. Phase analysis of the colloidal sample revealed anatase as the major phase up to 550 °C, while the polymeric route resulted only anatase phase up to 750 °C. On the basis of results, titania prepared by the polymeric route showed better thermal stability against phase transformation than the sample prepared by the colloidal route. Also, microstructural studies showed that titania nanopowder can be produced by both sol-gel routes
M. S. Saghian, R. Naghizadeh, H. Sarpoolaky,
Volume 10, Issue 2 (June 2013)
Abstract
In this study, the effect of different parameters such as time and temperature of calcination and milling on the formation of calcium aluminosilicates was investigated. Raw materials used in this study were calcium carbonate and kaolin in high purity. Powder X-ray diffraction patterns were obtained from all samples after heat treatment at various temperatures and times. To study the microstructure scanning electron microscope was used. Milling the samples contributed to the amorphous structure due to inducing defects in the structure. Moreover, increasing the milling time reduced crystallization temperature of anorthite. Uptake experiments were performed using solutions containing different concentrations of nickel. Samples were exposed to the solution for 24 h with stirring then the samples were filtered and the concentrations of the cations in the separated solutions were analyzed. FTIR analysis was conducted on the adsorbents before and after nickel uptake. Nevertheless, they hardly helped understand sorption mechanisms. Therefore, adsorption isotherms were studied instead. Three adsorption isotherms of Langmuir, Freundlich and DKR were used to model sorption data. Results suggested monolayer sorption occurs on the surface of the adsorbent and sorption energy calculated by DKR model was 22.36 kJ/mol which can be described as a strong chemical adsorption mechanism
