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UBC Theses and Dissertations

The effect of oxygen on the reaction between copper and saphire O’Brien, Thomas Edward


The effect of oxygen potential on the wetting behavior and interfacial energy between copper and sapphire was studied using the sessile drop technique in a CO-CO₂ atmosphere. A linear relationship was found between γ[sub SL] and log P0₂ from 10⁻⁶ to 10⁻⁵ atmosphere. Beyond 10⁻⁵ atmosphere γ[sub SL] approached a constant value asymptotically. A barrier surface layer was proposed to explain this change. The Gibbs' adsorption equation was used to evaluate the characteristic of the interfaces. Formation of a Cu₂O film at the liquid-vapour interface and a CuAlO₂ film at the solid-liquid interface was suggested. The work of adhesion was found to reach a maximum at approximately 10⁻² atomic precent oxygen. Measurements of the basal radius as a function of oxygen content were used to evaluate the role of oxygen in promoting spreading. It was found that spreading on sapphire was directly proportional to the logarithm of oxygen present in the molten copper drops. Evaluation of the penetration of copper into sapphire was evaluated using the electron probe microanalyser. Data obtained indicated that in absence of oxygen copper does not penetrate appreciably. Between 0.13 and 1.39 wt.% [0] copper penetration was not dependent on oxygen content and time. It was found that copper penetrates very rapidly initially and then appears to stop. An attempt has been made to obtain an equation based on the Young-Dupre equation, when the different energy values are affected the oxygen potential of the system.

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