Influence of the Cr Content on the Corrosion Properties of a Series of Binary Cobalt-Chromium Alloys in Acidic Artificial Saliva
Journal Title: Archives of Organic and Inorganic Chemical Sciences - Year 2018, Vol 2, Issue 1
Abstract
Cobalt-based alloys are more and more considered for dental applications, instead the expensive noble alloys and the other predominantly based alloys based on the allergen element nickel. These alloys frequently contain chromium to allow good resistance against corrosion as this may take place in the buccal milieu. The most often chromium is present in high quantity, close to 30wt. %, but it is maybe possible to decrease a little its contents without losing corrosion resistance. The aim of this study is exploring how the corrosion behavior of a cobalt alloy may vary versus its chromium content. In order to simplify this investigation only Co- xCrbinary alloys were considered, with x decreasing from 30 to 0wt.% by slices of 5wt.%. A series of seven alloys was synthesized by foundry under inert atmosphere and their behavior in corrosion in an artificial saliva of simple composition (NaCl 9g/L) acidified to pH=2.3 was specified using various classical electrochemical techniques (open circuit potential follow-up, Stern-Geary, Tafel, cyclic polarization). It appeared that passivation of the alloys occurred during the first two hours of immersion when the chromium content was 10 wt. % or higher, with as result high corrosion potentials and low corrosion current densities.. Crowns and other dental prostheses such as fixed partial dentures are reinforced metallic alloys to combat the intense stresses induced by mastication. Concerning fixed partial dentures the name of the complex piece supporting the cosmetic part of the prosthesis (artificial teeth) is framework. These frameworks are composed of "parent alloy" parts which are soldered to one another [1]. Different categories exist for the parent alloys. There the "High Noble" alloys (Au + Pt + ... > 60wt. % of noble metals), "Noble" ones (> 25 wt.%) and "Predominantly Base" alloys (less than 25wt% of noble metals). Many "Predominantly Base" parent alloys are based on nickel and contain chromium in rather high quantity for the resistance against corrosion in mouth. However nickel may potentially lead to allergic reactions [2]. Other "Predominantly Base" alloys also exist with not so serious problems: some alloys based on cobalt [3].
Authors and Affiliations
Estelle Kretz, Patrice Berthod
Keywords
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- EP ID EP602948
- DOI 10.32474/AOICS.2018.02.000128
- Views 54
- Downloads 0
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