In this study, we investigate the oxidation behavior of copper at temperatures below 300 °C and its mechanism. A methodology to slow down the oxidation rate is then proposed based on the observed mechanism. The oxides formed after oxidation at low temperatures have fine crystal sizes; the rate constants reach 2×10^-15 m²/s and 6×10^-14 m²/s at 200 °C and 300 °C, respectively. A passivation treatment at 600 °C in nitrogen produces a thin oxide layer composed of relatively large Cu₂O crystals. The presence of such a layer slows down the oxidation rate constants by an order of magnitude. This study demonstrates that the oxidation of copper at low temperatures is controlled by the grain boundary diffusion. Increasing the crystal size in the surface oxide reduces the oxidation rate significantly.

Different from the oxidation kinetics of other nitrides, the oxide layer on AlN can easily reach tens of micrometers at a temperature above 1200 °C. In the present study, the oxidation mechanism of AlN is investigated through microstructure observation. The analysis indicates that the oxide layer is full of small pores. The formation of pores generates additional surface area to induce further reaction. The reaction thus controls the oxidation in the temperature range from 1050 to 1350 °C. The oxidation rate becomes slow as the oxide layer reaches a critical thickness.