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.

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In this study, we have developed the manufacturing technology for high strength gray cast irons by using the spent permanent magnet scraps. The cast specimen inoculated by using a spent magnet scraps showed the excellent tensile strength up to 306MPa. This tensile strength value is 50MPa higher than that of the specimen cast without inoculation, and is similar to that of the specimen inoculated by using the expensive misch-metal. These superior mechanical properties are attributed to complex sulfides created during solidification that promote the formation and growth of Type-A graphite. It is therefore concluded that spent magnets scrap can provide an efficient and cost-effective inoculation agent for the fabrication of high-performance gray cast iron.