High-Temperature Corrosion of Copper Induced by TeO₂

It was found that copper is susceptible to the accelerated high-temperature corrosion induced by TeO₂ at 650°C in air, which occurs at a constant rate. The calculated corrosion rate constant is 4.5 × 10⁻⁴ kg·m⁻²·s⁻¹ and does not depend on the specific mass of tellurium oxide. Based on the results of the analysis of the microstructure (scanning electron microscopy/energy dispersive x-ray spectroscopy) and the phase composition (x-ray diffraction) of two formed corrosion layers, the phase distribution in the corrosion product has been ascertained. It was shown that during the corrosion process at 650°С, the inner corrosion layer containing Cu₂O and Cu₂Te and the outer corrosion layer mainly containing CuTe₂O₅ and Cu₂O were formed. The inner layer provides a high copper ion conductivity due to Cu₂Te, while the outer layer possesses a high oxygen ion conductivity due to the oxide melt. The mechanism of the overall corrosion process has been proposed.