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Mechanical Stresses during the Oxidation of Copper and Their Influence on Oxidation Kinetics. III
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1964
Year
EngineeringOxidation ResistanceMechanical EngineeringStructural MaterialsMetallurgyChemical EngineeringOxidation KineticsCorrosionMechanical StressesTheir InfluenceMaterials ScienceMaterials EngineeringMetallurgical InteractionSolid MechanicsOxidation RatePlasticityElemental MetalMicrostructureOxygen PenetrationHigh Temperature MaterialsCases DilatationMetallurgical ProcessMetallurgical SystemMechanics Of Materials
Bending and oxygen uptake of a helix of copper or of gold‐copper alloys, protected at one side by layers of silver and gold, were measured simultaneously between temperatures of 220° and 400°C and with oxygen pressures up to 140 mm Hg. The oxidation mostly showed an induction period and then followed a logarithmic law. In all cases dilatation of the oxide‐covered side of the helix was first observed, followed by a strong contraction. Finally, dilatation was found again. The effects increased if the oxidation rate was lowered, which was possible by change of temperature, oxygen pressure, or pretreatment of the metal. The stresses within the oxide were calculated as greater than , if related to layer thickness. They influenced oxidation kinetics and under special conditions were connected with whisker formation. The site of the stresses could be located experimentally. Epitaxy, hole formation within the metal, oxygen penetration through a porous layer, and transformation of the oxides into one another were found to be the factors which successively caused stresses, during oxidation.