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1

Using Electrochemical Noise Technique to Evaluate the Corrosion Performance of a Reinforcement Magnesium Alloy

Gobara M.

International Letters of Chemistry, Physics and Astronomy

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2015

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Vol. 40

61--72

EN

AZ91D magnesium alloy was reinforced by titanium and boron carbides under an inert environment using in-situ reactive infiltration technique. The corrosion properties of the reinforced magnesium alloy were investigated using Electrochemical noise (EN) techniques in dilute Harrison solutions. The moving average removal (MAR) method was used as trend removal methods. The frequency of pitting events (ƒn) and the average charge in each pitting events (q) were calculated for each EN measurements. EN results shows that the addition of reinforcement improved the corrosion resistance of the magnesium alloy (R-Mg) and no signs of corrosion were observed during 10 days of immersion in the corrosive solution.

2

Effects of TiO2/SiO2 reinforced nanoparticles on the mechanical properties of green hybrid coating

Gobara M.

International Letters of Chemistry, Physics and Astronomy

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2015

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Vol. 47

56--66

EN

Titanium and silica oxides nanoparticles were introduced into hybrid silica sol–gel/epoxy coating to enhance the mechanical properties of coatings. Titanium dioxide (TiO2) and silica oxide (SiO2) were chemically synthesised before adding to the prepared silica sol gel coating. X-ray diffraction (XRD), Energy-dispersive x-ray analysis (EDX) and Transmission Electron microscope (TEM) were used to characterize the prepared nanoparticles. The coating was then applied to 3003 aluminium alloy (AA3003) surface. The adhesion performance of different sol gel coating compositions was investigated using shear test to define the influence of nanoparticles on adhesive strength of the coating. The Rockwell C hardness test was used to study the micro-hardness of different compositions of sol gel coating. Also, contact angel was used to investigate the hydrophobicity of the coatings. The results showed that there was a significant improvement of the adhesion performance of hybrid silica sol gel coating due to addition of TiO2 and the hydrophobicity of sol gel coating was increased due to addition of SiO2 nanoparticles.

3

Tartrazine Solution as Dosimeter for Gamma Radiation Measurement

Gobara M., Baraka A.

International Letters of Chemistry, Physics and Astronomy

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2014

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Vol. 14, iss. 1

106--117

EN

In this study, Tartrazine aqueous solution was investigated as a simple low-dose dosimeter in the range of 20-500 Gy for the high ionizing radiation, gamma ray. Gradual bleaching of Tartarzine solution was observed with dose by measuring the absorbance of Tartarzine-solutions at specified wavelength, λmax = 428 nm. Tartrazine concentration (10–4, 5 ×10–4 and 10–3 M) and solution-initial pH value (5, 7 and 9) were considered as factors affecting degree of bleaching. It was found that Tartarzine-solution color was diminished gradually with selected dose range due to breakdown of the azo bond. The rate of bleaching increases with the increase of solution-initial pH. Increase of Tartarzine-concentration causes widening of range to which solution is susceptible. The post-irradiated effect (24 hours) was found to cause more bleaching. The sensitivity of Tartrazine solution is not regular with the Tartarzine-concentration and regular with pH.