Microanalysis of thin oxide film formed by high-temperature oxidation of commercial Ni-Cr alloy containing Be for metal-porcelain bonding.

Thin oxide films formed on commercial metal/porcelain Ni-Cr alloy containing Be, were studied by using the electron probe microanalyzer (EPMA) with the glass lining technique and by the X-ray diffraction method with the Debye-Scherrer camera. Oxidation was restricted to form thin oxide films as follows; at 700•Ž for 5 minutes in air, at 1,000•Ž for 2 minutes in air, and at 1,000•Ž for 40 minutes in vacuum (10-3 Torr). In the case of oxidation in air, the major oxides were NiO and Cr2O3, and the ratios of Cr2O3 to NiO were 0.57 at 700•Ž and 2.5 at 1,000•Ž. For oxidation in vacuum, only BeO and BeCr2O4 were detected. In all cases, the fine structure of the oxide film was modified in correspondence with the substrate alloy phase. These structural data and morphological data are discussed with respect to the general oxidation theory.