Investigating the Acid Failure of Aluminium Alloy in 2 M Hydrochloric Acid Using Vernonia amygdalina
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The acid failure of aluminium alloy in 2 M hydrochloric acid solution
in the presence of Vernonia amygdalina extract was investigated using
gasometric technique. Aluminium alloy coupons of dimension 4 cm by 1 cm
were immersed in test solutions of free acid and also those containing extract
volumes of 2, 3, 4 and 5 cm3 at ambient temperature for 30 minutes. The
volumes of hydrogen gas evolved as a result of the rate of reaction were recorded
and analyzed. Analysis revealed that maximum inhibitor efficiency which
corresponds to the lowest corrosion rate was obtained at optimum inhibitor
volumes of 5 cm3, with reduction in the corrosion rate observed to follow in
order of increasing extract volumes. Adsorption study revealed that Temkin
isotherm best described the metal surface interaction with the extract
phytochemicals, with 12 minutes becoming the best exposure time for the
phytochemicals to adsorb to the metal surface at all volumes. Statistical
modelling of the corrosion rate yielded an important relationship suitable for
estimating corrosion rate values once volumes of the extract is known.
Microstructural studies, showed an indirect relationship between crack growth
rates and extract volumes, while consistency of the irregular intermetallic phases
increases with increasing extract volumes.
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TJ Mechanical engineering and machinery