Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : sulfuric acid

Performance of Self-Compacting Concrete Containing Pozzolanic Materials in Aggressive Environment

L.A. Zghair; Q.J. Frayyeh; M.M. Salman

Engineering and Technology Journal, 2017, Volume 35, Issue 5, Pages 439-444

The aims of this study is to investigate the resistance of different SCC mixtures to aggressive solutions. The investigation included the type of the cementitious materials (silica fume and high reactivity Attapulguite-HRA) and limestone powder (chalk powder and Al-gubra). The powder content of the mixes was kept constant, 500 kg/m3. The slump flow, L-box, and V-funnel were performed for mixes in there fresh state. In the present work, the specimens were immersed in sulfuric acid solution with a concentration of 0. 5% up to 289 days after normal curing for 28 days. After concrete has hardened, two types of test are performed. Firstly, destructive tests are conducted including (compressive strength, splitting tensile strength, and modulus of rupture). Secondly, a mass loss as non-destructive test is performed. The results obtained from this work, show that concrete mixes with chalk powder only, had the best resistance to sulfuric acid solution comparable with concrete made with Pozzolanic materials the reduction in compressive strength was 25. 9 %. In addition, concrete mixes with HRA had the worst resistance.

Galvanic Corrosion of Carbon Steel –Copper in Aerated H2SO4 Under Agitation Conditions

Muayad F. Hamad; Huda D.Abdul Kader; Basim O. Hasan

Engineering and Technology Journal, 2015, Volume 33, Issue 9, Pages 2107-2118

Galvanic and free corrosion experiments on carbon steel-copper couple in 3% H2SO4in the presence of NaCl salts were carried out under different operating conditions. The effect of temperature, agitation speed, and air bubbling (O2 concentration) on the free and galvanic corrosion was studied and discussed. The galvanic corrosion was investigated by both weight loss method and by determining the galvanic currents using zero resistance ammeter (ZRA). The results revealed that increasing temperature leads to increase the galvanic corrosion rate and also the free corrosion rate of each metal. Increasing agitation velocity enhanced the galvanic corrosion rate in a manner depending on temperature. The presence of air bubbling increased the corrosion rate and galvanic currents at low air pumping rate, while, at high pumping rate, air bubbling decreased the corrosion rate.

The Determination of Optimum Conditions for Anodizing Aluminum Alloy (6063)

Uday Sami Mohammad; Sami A.Ajeel

Engineering and Technology Journal, 2008, Volume 26, Issue 11, Pages 1341-1354

Aluminum alloy (6063) has been anodized using sulfuric acid as an
electrolyte. To study the characteristic of the anodic film, four variables, were
considered as the most dominant variables. These variables are: current density in the
range of 1- 4 A/dm2, electrolyte concentration in the range of 6 - 20 vol.%, electrolyte
temperature in the range of 10- 30oC and anodizing time between 12- 60 min.
These four variables are manipulated through the experimental work using Box –
Wilson experimental design where second order polynomial model was proposed to
correlate the studied variables with the thickness of anodic film of aluminum alloy
(6063) to estimate the coefficients of the proposed polynomial adopted via statistica
The predicated models are found after statistically analyzing the significance as
Y= 27.7800 + 8.0737X1 - 0.8037X3 + 8.2078X4 - 0.6994X2
1 - 0.8882X2
- 1.5582X2
3 - 1.1231X1X2 + 2.6225X1X4 - 1.7931X2X3 - 1.6956X2X4
- 1.0581X3X4
where Y is the objective function (thickness of anodic film), X1 is the current density;
X2 is the electrolyte concentration; X3 is the temperature of electrolyte and X4 is the
anodizing time.
The study shows that the anodizing time and current density had shown positive
dependence of great significance on the anodic film thickness while the other two
studied variables (i.e. concentration and temperature of electrolyte) had shown small
dependence on the film thickness of aluminum alloy (6063).
Optimum conditions for achieving the maximum film thickness are obtained from
optimizing the above correlation and are found as follow: 4 A /dm2 Current
density, 6 vol. % Acid concentration, 19.5 oC Electrolyte temperature and 60 min.
time of anodizing.

Improving Anodizing Efficiency by Adding Different Amounts of Aluminum Powder to Anodizing Electrolyte for Pure Aluminum and Aluminum Alloy (6063)

Uday Sami Mohammad; Sami A. Ajeel

Engineering and Technology Journal, 2008, Volume 26, Issue 7, Pages 842-865

Different amounts of aluminum powder (5, 7, 9 and 11g/l) were added to sulfuric
acid solution of the specimens under ideal conditions previously obtained (1) and the
effect of these additions was studied to find out it's benefit on anodizing efficiency for
pure aluminum and aluminum alloy (6063).
The specimens were examined in different conditions using optical microscope,
roughness and hardness measurements.
The study shows the anodizing process was improved by adding aluminum
powder with ideal conditions and the best value of aluminum powder was 9g/l,
where the thickness improved from 72.25μm at ideal conditions to 81.25μm with
adding 9g/l aluminum powder and the coating ratio improved from 1.481 at ideal
conditions to 1.541 with adding 9g/l aluminum powder for pure aluminum, while the
thickness improved from 74.56μm at ideal conditions to 82.29μm with adding 9 g/l
aluminum powder and the coating ratio improved from 1.417 at ideal conditions to
1.471 with adding 9g/l aluminum powder for aluminum alloy (6063).
The study also shows that the effective anodic current efficiency was increased
about 12.50% when adding aluminum powder of 9g/l compared with ideal conditions
for pure aluminum, while this value was increased about 10.20% when adding
aluminum powder of 9g/l compared with ideal conditions for aluminum alloy (6063)
without adding aluminum powder.
It is found that the surface roughness and hardness value of specimens with adding
aluminum powder of 9g/l gives the best result compared with the specimens at ideal
conditions and bare specimens.