Effect of Heating Atmosphere Composition and Content on Phase and Morphology Distribution of Copper Oxide Layer

When a copper billet is heated in the rolling reheating furnace, certain oxides that affect the surface quality may persist on the substrate. This study investigates the effects of heating atmosphere compositions (N₂, O₂, CO₂, and H₂O) and contents on the micro-morphology and phase evolution of the copper oxides. The results revealed that O₂ is the primary factor contributing to the formation of nodules on the copper surface. The primary phase of the exfoliated oxides was CuO attached to Cu₂O, and the nodular oxides also consisted of CuO that directly adhere to copper matrix. Additionally, water vapor can increase the number of Cu₂O particles on the interface between exfoliated oxide and copper matrix, effectively reducing the number of residual nodular oxides. Finally, water vapor and its dissociation products effectively eliminated the pores within the oxide layer and at the oxide–matrix interface, while CO₂ increased the porosity within the oxide layer.