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Missouri University of Science and Technology

Doctoral Dissertations

Corrosion

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Full-Text Articles in Engineering

Corrosion Protection Mechanisms Of Trivalent Chromium Based Passivations On Γ-Znni Coated Al6061-T6 Alloy, Kevin Foster Jan 2022

Corrosion Protection Mechanisms Of Trivalent Chromium Based Passivations On Γ-Znni Coated Al6061-T6 Alloy, Kevin Foster

Doctoral Dissertations

“The role of cobalt in trivalent chromium passivations (TCPs) to improve corrosion resistance of γ-ZnNi coated steel and aluminum is based on its effect on hexavalent chromium content in the passive layer. Investigations of both a cobalt-containing and cobalt-free TCP on SAE 1008 steel indicated that both passivations protect well for up to 1000 hours in neutral salt spray exposure (SSE). A repetition on Al 6061-T6 alloy indicated that TCP performed much better than cobalt-free TCP implicating the underlying substrate. Optical and electron micrographs indicated physical changes such as crack thickness, crack density, passivation porosity, and passivation thickness existed between …


Phosphate-Doped Borosilicate Enamel Coating Used To Protect Reinforcing Steel From Corrosion, Xiaoming Cheng Jan 2014

Phosphate-Doped Borosilicate Enamel Coating Used To Protect Reinforcing Steel From Corrosion, Xiaoming Cheng

Doctoral Dissertations

"Phosphate-doped sodium borosilicate glasses were developed for enamel coatings to provide corrosion protection for reinforcing steel in concrete. Phosphates have low solubilities in borosilicate glasses, generally less than about 4 mol%, and are incorporated mainly as isolated PO43- and P2O74- anions, along with some borophosphate bonds. With the addition of P2O5, the silicate network is repolymerized and tetrahedral borates are converted to trigonal borates, because the phosphate anions scavenge sodium ions from the borosilicate network. The addition of Al2O3 significantly increases the solubility of P2O …