Abstract
To clarify the interface reaction between porcelain and a commercial Ni-Cr dental alloy (containing Be) during porcelainization, electron probe micro analyzer (EPMA) and X-ray diffraction method have been used to characterize the interface which emerged by selective dissolution of the alloy caused by the bromine-methanol solution. Elemental distribution maps across the reaction layer have been provided by alternating EPMA and etching the interface by 1 micron meter depth with Ar ion RF sputtering. At an early stage of porcelainization, a large amount of Ni oxide was generated. However, a long fusing interval resulted in the reduction of such a oxide and oxidation of Be became a dominant reaction. This is because porous porcelain particles change into airtight sintering glass and, as a result, oxygen partial pressure at the interface falls remarkably. Under this condition, oxidation depends upon the equilibrium dissociation pressure of each oxide rather than the alloy composition.
