[Analysis of the oxide film of Ni-Cr porcelain alloy].
OBJECTIVE
In order to find out the causes of cervical gray line of PFM crown, the features of oxide film of Ni-Cr alloy were investigated.


METHODS
1. The phases were analyzed using x-ray radiation shield. 2. Compositions of oxide film and base metal were measured using electronic scanning microscope. 3. The thickness of oxide film and the variations of Ni, Cr, O in oxide film were evaluated using Auger electron spectroscope.


RESULTS
1. There were not only NiCr2O4 but also Cr2O3, SiO2, and gamma phase solid solution in the surface. 2. The weight contents of Cr and Si were higher while Ni was lower in oxide film than in the base. 3. Oxide film became much thicker(400 nm: 16 nm) after the temperature cycling.


CONCLUSIONS
The medium-thicked oxide film was formed after baking, and it was not a complete film.
Xu
J
J
School of Stomatology, Beijing Medical University, Beijing 100081.
Guo
J
J
D002858:Chromium Alloys / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D003778:Dentures / Q000379:methods; D006801:Humans; D016876:Metal Ceramic Alloys / Q000737:chemistry*; D009532:Nickel; D010087:Oxides / Q000032:analysis*; D014131:Trace Elements
D002858:Chromium Alloys; D016876:Metal Ceramic Alloys; D010087:Oxides; D014131:Trace Elements; D003776:Dental Porcelain; D009532:Nickel