Bonding mechanism evidence in a ceramic--nonprecious alloy system

Bonding between porcelain and dental ceramic alloys is thought to be dependent upon the establishment of a continuous electron structure across the ceramic-metal interface (Pask, Proc. Porcelain Enamel Inst.,33,1,1971). Such a structure most likely results from the compatibility of metal ions at the metal surface saturated in an oxide form with the complex oxide structure of the ceramic matrix. Reaction zone compounds are expected to play a prominent role in the strength of the ceramic-metal bonds but thus far none have been detected or identified. The present study was centered on the determination of possible adherence zone compounds in four composite ceramic-metal couples examined by x-ray energy analysis. Elemental analysis of four couples revealed the presence of a predominant Al-Cr interaction resulting from the formation of an Al-Cr-O compound or mixed complex. The Cr ions were supplied by the Cr2O3 oxide layer at the metal surface and the Al was provided by the initial bonding-agent coating.