L'oxydation sèche du cuivre et de ses alliages IV. Oxydation d'un alliage de cuivre et de beryllium

Abstract

Summary. ‐ The oxidation of a copper base, copper‐beryllium alloy (2% beryllium) has been studied at temperatures ranging from 200°C to 800°C. Oxidation products have been identified by the electron microscope, by X ray and electron diffraction. The quantities of cuprous and cupric oxides formed, have been evaluated separately by a coulometric method. The kinetics of the reactions leading to the formation of copper oxides have been studied. No quantitative data have been obtained concerning beryllium oxides.It has been shown that a continuous film of beryllium oxide is formed at all temperatures but is very thin below 450° and suddenly thickens at higher temperatures. The copper oxide films are always discontinuous. At temperatures lower than 400°, cubes of cuprous oxide are revealed by the electron microscope. Needlelike crystals of cupric oxide grow outwards from the cuprous oxide cubes. This confirms the electron diffraction and kinetic data which lead to the conclusion that the primary product of the copper oxidation, in the alloy as in the pure metal, is always cuprous oxide. The cupric oxide appears as an oxidation product of the lower oxide.The presence of a continuous film of beryllium oxide confers a highly protective character to the oxidation products of the alloy.