Oxidation and Ceramic Coatings on 80Ni20Cr Alloys

Abstract

Additives and/or impurities in NiCr alloys would be expected to affect the oxidation and adherence of dental glasses. Oxidation characteristics and bonding of several glasses to a commercial impure 80Ni20Cr alloy and laboratory-prepared purer alloys were thus studied at 1000°C. The commercial alloy formed a porous and buckled single-layer oxide scale with lenticular voids at the interface. The scale was penetrated by glass which formed a chemical bond at the alloylglass interface, resulting in excellent adherence with fracture in the glassy phase. The purer alloy formed a complex multilayer oxide scale to which the glass bonded but did not penetrate; the assembly was not satisfactory, since fracture occurred in the oxide scale.

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