Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : gel


Gas Sensitivity of ITO Composite Prepared by Sol-Gel Method

R. J . Halbos; S. AL-Algawi; R.T. Rasheed

Engineering and Technology Journal, 2017, Volume 35, Issue 10, Pages 981-986

Indium oxide and indium tin oxide composite (ITO) were prepared by sol-gel dip-coating (SGDC) technique. The particles annealed at (200 ◦C, 400 ◦C). The structure and surface morphology of particles were characterized by X-ray diffraction (XRD), Atomic Force Microscope (AFM), FT-IR and UV/visible measurements. The XRD and AFM indicate decreasing in the particle size and improve of optical and electrical properties of composite with increasing of tin oxide addition. The hall measurement were used to obtain information about the type of conductivity of indium oxide and indium tin oxide thin films and carrier concentration and mobility and resistivity, the results of Hall measurements show that the In2O3 and ITO composite have n-type. The thin film of composite ITO at composition (80:20) mole ratio has high sensitivity toward CO gas compared with pure indium oxide.

The Effect of Annealing Temperature on Structural & Optical Properties of Nanocrystalline SnO2 Thin Films Prepared by Sol-Gel Technique

Selma M.H. AL-Jawad; Abdulhussain K. Elttayf; Amel S. Sabr

Engineering and Technology Journal, 2016, Volume 34, Issue 4, Pages 490-498

In this work, studying the structural and optical Nano crystalline SnO2 thin films grown on cleaned glass substrates by using sol- gel (dip coating) technique. It is worthy to say that the thickness of the deposited film was of the order of (300-400)nm . The films are annealed in air at , 300◦C, 400◦C and 500◦C temperatures for 60 minutes. The films that are analyses by X-ray diffraction (XRD), Scanning electron microscopy (SEM) , atomic force microscopy and optical absorption spectroscopy technique. The size of crystalline was observed, as well as, so as to increase with increasing annealing temperature . XRD analysis reveals that the whole films are polycrystalline with tetragonal structure with preferred orientation of (110),(101),(200) and (211) . The increase of annealing temperature leads to raise the diffraction peaks and decrease of FWHM. The atomic force microscopy (AFM) and Scanning electron microscopy (SEM) results showed that the average grain size was increase with the increase in annealing temperature. Spectra of transmittance and absorbance was recorded at wavelengths range (300-1000)nm .The optical properties showed high transmission at visible regions. The optical band gap energy was found to be (3.5 , 3.75 , 3,87) eV at annealing temperature (300,400,500 )°C respectively.

Experimental Stability and Thermal Characteristics Enhancement Analysis of Water Based Boehmite Nano fluid

Atia; Mohammed Hussein J. Al; Sarah A. Abed

Engineering and Technology Journal, 2015, Volume 33, Issue 7, Pages 1193-1210

In this work attempt was made to formulate water based boehmite (AlOOH) nanofluid in one and two steps methods. Boehmite is the first born alumina phase as prepared by sol gel route using aluminum isopropoxide precursor, exhibit a combination of excellent consistency and dispersibility in water. Plain nanofluids containing boehmite at different concentrations were investigated for colloidal, suspensions and/or dispersions stability and thermal conductivity enhancement. X-ray diffraction analysis, laser diffraction particle size analysis, viscosity, thermal conductivity measurements, TG/DSC thermal analysis and sedimentation balance were used as characterization tools. The results show promising long-term fluid stability and thermal conductivity enhancement relative to starting based fluid following non-linear dependence on particles concentration. The maximum 2.7 times enhancement in thermal conductivity occurred at narrow boehmite concentration range as a result of achieving optimum nanoparticles aggregation level where neither the case of nanoparticles homogenous dispersion nor the case of fully aggregated clusters could retain these enhancements values. This far beyond behavior from Maxwell's model was explained on the basis of the known mechanisms of thermal conductivity enhancement of nanofluids.

Synthesis of Nano-TiO2 Thin Films by Sol-gel Dip-coating Method

Bushra R. Mahdi; Abass F. Al.mamori; Adnan meship Mahdi

Engineering and Technology Journal, 2015, Volume 33, Issue 7, Pages 1303-1312

Synthesis of titanium dioxide (TiO2) Thin film on three microscope glasses using sol-gel method has been studied intensively. The starting materials were titanium(III)chloride, Ammonium Hydroxide. The components were mixed together to form the sol. Then, at 50℃ heating and ageing was applied to form stable sol-gel . Every glass substrate dipping in sol-gel beaker for period time (1,3,5)min respectively, for obtaining different thickness films. To evaluate the performance of films, After annealing at 500℃ , the crystallinity of the films was determined by using the x-ray diffractometer (XRD). The change on the surface morphology was observed using Atomic Force Microscope(AFM). Finally, Optical properties measurements Absorbance (A) and transmittance(T)) for (TiO2) films were studied by UV-Visible spectrometer.
analysis on the films. It has been successfully shown that the anatase crystalline phase was observed when the TiO2 thin film was annealing at 500°C. The roughness and the crystalline size of TiO2 thin film changed with the thickness. The minimum grain size( 6.92) nm for thickness 1.2µm UV-visible studying that absorption is maximum at UV spectrum (opaque) and the transmittance is maximum at the visible spectrum

Synthesis and Studying Dielectric Properties of Mixed Nanoferrites

Zainab I. Dhary; Mohammed S. Hamza; Fadhil A. Chyad

Engineering and Technology Journal, 2015, Volume 33, Issue 1, Pages 154-164

Based on a low temperature route (sol-gel autocombustion) a nano-ferrite CoFe2O4and Li0.5Fe2.5O4 and different percentages of cobalt-ferrite are synthesized. The crystalline structure by XRD and dielectric properties with TEM micrographs are presented. The XRD (crystallite size and lattice parameter) are determined which affected by cobalt content. TEM micrographs show a nano-particles in the range of (8-20) nm which correlate with crystallite size. Dielectric properties (dielectric constant, loss tangent and dielectric loss factor) are decreased with frequency and cobalt content.

Coating of Carbon Fibers With Calcium Phosphate by Sol- Gel Method

Sewench N. Rafeeq; Wafaa A. Husaien; Russel Rushdi Ghanim

Engineering and Technology Journal, 2014, Volume 32, Issue 5, Pages 1117-1128

Sol-gel technique has been used to coat carbon fibers with calcium phosphate to improve the esthetic of black carbon fibers as it's biocompatible. To improve bonding between carbon fibers and prepared calcium phosphate powders, the surface of carbon fibers has been treated with para-aminobenzoic acid. The structural tests include: (SEM, XRD, AFM and FTIR). The morphology of the coating layers has been examined by scanning electron microscope (SEM). The crystallized phase composition of coatings has been identified by x-ray diffractometry (XRD). The grain size of dried and heat treated calcium phosphate coat has been estimated by atomic force microscope (AFM) and fourier transform ــ infrared spectroscopy (FTIR) analysis which support and verify the x-ray diffraction findings.

Synthesis of B4C/YTZP Composite Powder and Studying Effect of its Addition on Mechanical Properties of B4C

Fadhil A. Chyad; Mohammed H. AL-Taie; Hussein AlaaJaber

Engineering and Technology Journal, 2014, Volume 32, Issue 5, Pages 1158-1170

In this research B4C powder have been coated with yttria stabilized tetragonal zirconia polycrystalline (YTZP) (ZrO2 – 6wt% Y2O3) by using sol-gel method in order to obtain on composite powder (B4C core/ YTZP shell, 1/1 wt%). Zirconium oxychloride (ZrOCl2.8H2O) and yttrium nitrate (Y(NO3)3.6H2O) were used as the precursors for synthesis of the YTZP compound. The coated B4C powder was then used as additive powder to B4C. It was mixed with different percentages for making ceramic–ceramic composite samples. The YTZP weight percentages added to the B4C were in the range (0–12.5) wt%. The samples sintered by using spark plasma sintering technique at 1800 and 1900°C for 5 min. Density and mechanical properties (Vickers microhardness, fracturetoughness and fracturestrength) for the sintered samples were measured. The results show that the best YTZP additions to the B4C that have good mechanical properties were ranged 5 – 7.5 wt%.

Synthesis and Studying SomeMechanical Properties of Nanocomposite

Fadhil A. Chyad; Abdul-Raheem K.Abid Ali; Auday A. Mehatlaf

Engineering and Technology Journal, 2013, Volume 31, Issue 7, Pages 1221-1228

This study aims to synthesis a nanocomposite from Al2O3 – Cr2O3 and studying some of its mechanical properties like microhardness and fracture strength.
X-Ray diffraction patterns shows a good crystallinity of the composite with very sharp and neat peaks. TEM photographs shows the good distribution of the particles which have an average particle size of (3-6 nm). The microhardness is increased with the increasing of sintering temperatures having the height value at 15% chromia while the fracture strength behaves as a bell shape having again the height value at 15% chromia.

Comprehensive Electrochemical Evaluation of Protective Coatings Properties by Sol-Gel Route for Stainless Steel Corrosion

Atia; Mohammed Hussein J. Al

Engineering and Technology Journal, 2013, Volume 31, Issue 4, Pages 71-86

Sol gel nano ceramic coatings have been applied on stainless steel to develop their biological characteristics and increase resistance to corrosion and wear. In this work nine electrochemical parameters were calculated, adopted to set a comprehensive evaluation map for protective properties of the coatings obtained based on occurrence degree of cracks, porosity, general and localized corrosion by using d.c. Potentiostate utilized for measuring the polarization curve in 3.5% NaCl solution at 250C for a single alumina layer deposited on stainless steel specimens by the dipping technique from four solutions containing different alumina concentration 0.25, 0.26, 0.61 and 0.93 mole/liter prepared by dissolving aluminum isopropoxide in water, the coats were then heat treated to 6000C. The results showed the possibility of obtaining clear protective properties that facilitate the comparison between the types of thin coatings deposited on the surfaces of the stainless steel by sol gel method.