Fabrication of A g– S n O ₂ Contact Materials from Gas‐Atomized A g– S n Powder Using Combined Oxidation and Ball‐Milling Process

Silver–tin oxide (Ag–SnO ₂ ) is considered to be an effective alternative to silver–cadmium oxide (Ag–CdO), which is carcinogenic and, therefore, toxic to the human body. In this study, Ag–SnO ₂ powder was prepared through a combined oxidation and ball‐milling process using gas‐atomized Ag–Sn powder. During oxidation, the Ag ₃ Sn phase disappeared at 800°C and SnO ₂ was formed without Ag oxidation; this SnO ₂ formed a layer structure that covered the Ag matrix. The thickness of the oxide layer increased after the composite was subjected to a second oxidation process. Owing to the resultant core (Ag)‐shell (SnO ₂ ) structure, the electrical conductivity of the fabricated composite was considerably lower than that of commercially available materials. However, the electrical conductivity increased remarkably after ball milling of the samples, which allowed the SnO ₂ surface layer to be peeled off and crushed. Following high‐pressure magnetic pulsed compaction, the SnO ₂ was found to be homogeneously distributed in the Ag matrix, which exhibited a lamellar structure.