Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : porosity

Effect of Degassing Process of Squeeze Casting Aluminum Alloy on Tensile Strength Under Different Pressures

Hussain J. Al-alkawi; Dhafir S. Al-Fattal; Samih K. Al-najjar

Engineering and Technology Journal, 2015, Volume 33, Issue 2, Pages 320-330

Degassing technique currently applied to cast aluminum alloys due to its technological and economic advantages. The present work aimed to study the effect of degassing technique of cast aluminum alloy (LM2) under different pressures using squeeze casting process. Inert argon gas was pumped into the molten aluminum with flow rate (2,5-5-7)l/min. at constant pumped duration (5min.). Different applied pressures were used(17, 35, 52) MPa. The test was performed at room temperature. The physical and mechanical properties of degassed samples were measured and compared with non-degassing (ND) samples. The results showed that the best condition of degassing is found at 2.5 l/min flow rate and 35 MPa applied pressure. It was found that a slight difference is observed for the density and the lowest value of porosity was obtained at 2.5 l/min flow rate and 52 MPa applied pressure.

Preparation and Characterization of Porous Silicon Prepared by Electrochemical Etching

Adawiya J .Haider; Jassim M. Abass; Omar abdulkreem

Engineering and Technology Journal, 2014, Volume 32, Issue 4, Pages 623-628

Porous silicon (PS) layers were formed on p-type silicon (Si) wafers by using electrochemical etching method. The influence of varying etching time in the anodizing solution ,on structural and optical properties of porous silicon has been investigated. Additionally , the thickness and porosity of the layers were measured using the gravimetric method. The surface morphology was studied by Scanning Electron Microscope (SEM). Finally, the optical properties of porous silicon on silicon substrates were investigated by employing photoluminescence (PL).

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.