Structural Changes in the Oxidation Zones of Gold Alloys for Porcelain Bonding Containing Small Amounts of Fe and Sn

Abstract

The oxidized surfaces of cross-sections of gold alloys containing a total of 1.5 mass % Fe and Sn, oxidized at 1000 °C for one hr, have been studied by various techniques, including secondary electron micro-analysis, X-ray micro-analysis, X-ray diffraction, and thermogravimetry.

Over the composition range (0.30 - 1.50 mass % Fe), an external oxidation zone containing only Fe oxides was formed. The quantity of Fe203 was greater than that of Sn02 for 0.45 - 1.50 mass % Fe. With an Fe content below 0.45 mass %, the amount of Sn02 was greater than that of Fe₂O₃ . Traces of Fe304 were formed in high Sn content alloys.

Internal oxidation particles composed of Fe203 and Sn02 precipitated deep in the alloy matrix (0.90 - 1.50 mass % Fe), and these changed to an internal oxidation band composed mainly of Sn02 for 0.3 mass % Fe.

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