Performance evaluation and oxide layer characterization of self-protective Cu/W–La₂O₃ composite electrodes prepared by gas pressure infiltration for continuous arcing in air

Abstract This study evaluates the erosion resistance and thermal stability of Cu/W–La 2 O 3 composite electrodes exposed to plasma arc conditions in ambient air. Through comparative analysis with pure copper and W–La 2 O 3 electrodes, it was found that the Cu/W–La 2 O 3 composites exhibit superior erosion resistance, with a notably advantageous negative erosion rate due to a self-formed oxide layer that mitigates surface degradation. Detailed microstructural characterization revealed that this oxide layer, primarily consisting of copper tungstates and lanthanum tungstates, enhances electrode durability by reducing oxidation rates and improving heat dissipation. This adaptive surface layer also contributes to a more stable arc, effectively minimizing material loss, particularly at higher current intensities where pure copper electrodes experience rapid thermal and oxidative degradation. The findings suggest that Cu/W–La 2 O 3 composites, with their negative erosion rates, offer significant benefits for air plasma torches, making them promising candidates for applications demanding high-performance and long-lasting electrodes in oxidizing environments.