ABSTRACT
Our knowledge on the bonding mechanisms between the metal and ceramic parts of dental systems is very limited. This work tested the hypothesis that the details of the interface processes can be described in the framework of a chemical diffusion model. The development of interfacial phases was investigated by cross-sectional analytical transmission electron microscopy between a NiCr (Wiron 99) alloy and three different dental ceramics (Carat, Vita VMK 95, and Vision). All systems were investigated at normal firing conditions (suggested by the manufacturer) and at increased firing times as well. The conclusions are based on the results that the formation of a nanocrystalline Cr(2)O(3) layer and amorphous silicon oxide inclusions were detected in the early stage of the firing process in all investigated systems, and that, in the case of Carat and Vision ceramics, formation of complex NiCr and NiCrTi oxides was also observed at longer annealing times.
Subject(s)
Chromium Alloys/chemistry , Metal Ceramic Alloys/chemistry , Chromium Compounds , Crystallization , Diffusion , Microscopy, Electron , Nickel , TitaniumABSTRACT
In this investigation we observed the interface between Wiron 99 (Bego) dental Ni-Cr alloy and Vision (Wohlwend AG) ceramic opaquer with SEM. In the system there are intermediate phases coming from a solid phase rection which play an essential role in the metal-ceramic bond. The analytical methods showed that in this phases the content of Ni and Cr charge not monotonously from alloy to ceramic which shows strong chemical effects (the selective affinity of Cr and Ni). The concentration of Cr after the alloy surface increases in a 1-1.5 microns layer, where its concentration is higher than at the alloy, while the concentration of Ni decrease in this layer. Than at the ceramic side of the reaction zone the concentration of Ni increases in a 1-1.5 microns wide layer where its concentration is near upon that one in the alloy.
