Optical microscopic study of the stress induced corrosion of brass and aluminium in dilute electrolyte, and the inhibition effect of Cedrus Atantica and Ocimum Basilicum

Department of Mechanical Engineering, Covenant University, Ogun State, Nigeria

^* Corresponding author: tolu.loto@gmail.com

Abstract

Optical microscopic analysis of the stress induced (85% calculated stress) corrosion of brass in 1M ammonium sulfate [(NH₄)₂SO₄] + 1M copper (II) sulfate (CuSO₄) solution, and aluminium in 0.5M, 1M and 2M sulfuric (H₂SO₄) solution at 10% and 20% addition of Cedrus Atlantica and Ocimum basilicum Linn. essential oil extracts were documented. The optical images obtained showed the effect of both extracts on the alloys. Optical images of aluminium in the presence of Cedrus Atlantica showed increased susceptibility of the alloy to localized and general corrosion compared to Ocimum basilicum Linn which enhanced the corrosion resistance of aluminium. Cedrus Atlantica increased the susceptibility of alpha brass to corrosion compared to the solution without it. In the absence of Cedrus Atlantica, general surface deterioration was observed without any localized corrosion. However, at 10% Cedrus Atlantica concentration superficial crack was observed. The crack further increased to visible intergranular crack (fracture) at 20% Cedrus Atlantica concentration. Ocimum basilicum Linn performed effectively at 10% concentration, sustaining the corrosion resistance of brass in 1M (NH₄)₂SO₄ + 1M CuSO₄ solution. At 20% Ocimum basilicum Linn concentration superficial cracking appeared.