Abstract:
Steel substrate with 0.4 % carbon was hot-dip-aluminized, at 800 °C for 1 minute, in pure Al and Al-Cu alloys containing 2.5 to 15% Cu by weight. In aluminizing, an interlayer developed between the aluminizing metal and the steel substrate. The changes in its growth and morphology, and formation of phase constituents due to Cu additions in Al were studied. In correlation, the mechanical and oxidation properties of the hot-dip coatings were also investigated. This investigation was made by optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA). The interlayer was thick and exhibited finger-like interface between itself and steel substrate, when aluminized in pure Al. The decrease of interlayer-thickness was observed with gradual increase in Cu % from 2.5 to 11. Whilst further increase in Cu content, even up to 15%, did not reduce the interlayer-thickness. However, it endeavored to transform its finger-like interface to smoother one. XRD analysis revealed that Cu addition in Al forms tetragonal phases-Al2Cu and Al7Cu2Fe in the coating, which reduce diffusion of Al atoms through the interlayer and in due course reduced the growth of the interlayer. Oxidation resistance, of the steel aluminized in Al-Cu alloys, was comparable with pure Al and Al-Si alloys but, its hardness was much higher.
Page(s):
149-164
DOI:
DOI not available
Published:
Journal: Journal of Quality and Technology Management, Volume: 6, Issue: 2, Year: 2010