Poster De Conférence Année : 2016

Influence of the chemical composition and of the hardened state of four cast Ni-based and Co-based cast alloys on their behaviour in corrosion by an artificial saliva. Part 1: Case of the nickel alloy studied using stationary electrochemical techniques and EIS

Résumé

In one of the numerous medical fields, odontology is among the ones in which metallic alloys are often employed. Stainless steels are employed for archwires in orthodontics, titanium alloys to fix individual teeth in jaw bone by surgical intervention, more or less noble metals (gold, platinum, palladium, silver…) in other applications of prosthetic dentistry. In the last example nickel-based alloys may replace noble alloys in the frameworks reinforcing mechanically fixed partial dentures. The association of nickel-based parent a lloys sold together with primary and secondary solders, hidden by the artificial teeth the role of which is only aesthetic, allow the prosthesis resisting the bending solicitations during mastication. The use of nickel alloys started several decades ago, despite the biocompatibility and allergy problems which are often evocated about this element. They represent an interesting economic alternative since some of them may be simultaneously mechanically and corrosion resistant. However their elaboration and shaping may present some possibly problematic specificity (castability, chemical homogeneity, heat-treatments …). Nickel-based alloys as dental materials are present in the catalogue of various manufacturers besides traditional nobler alloys Au-based or Pt-based for example. Ivoclar Vivade nt®, for instance, proposes the Pisces Plus (61.5Ni-22.0Cr-11.2W-2.3Al-2.6Si, all contents in wt.%) and the 4ALL (61.4Ni-25.7Cr-11.0Mo-1.5Si, in wt.%). Their base element is thus nickel and significant amounts in chromium are present to favour high corrosion resistance. Additional elements W or Mo, and Si or Al, also belong to their chemical composition: they are added to optimize their response to heat treatment and to improve their mechanical and corrosion resistances. The mechanical properties of these alloys are of course of very high importance since this is in this field that they are used. But, knowing that, as the post-solder alloy, the extremities of the elemental parts of parent alloys are also possibly exposed to the buccal milieu, they must be themselves resistant against corrosion to be not at the origin of release of Ni2+ ions in mouth which can be dangerous for allergic patients. Since modifications can be brought to the alloys for their mechanical improvement, it is of great importance to better know the possible consequences of such changes for their corrosion resistance. This is the purpose of a latter work concerning the Pisces Plus alloy. Indeed, changing the chemical composition of the Pisces Plus alloy to study the effect of its microstructure and corrosion properties was earlier tested and the new properties investigated in a previous work. In the present study this is the 4ALL alloy which will be subjected to chemical modification and to the study of the consequences on its corrosion properties. This will be explored by applying electrochemical methods to alloy electrodes immersed in a solution simulating saliva. Additionally, since hardening may result from mastication for the thinnest parts of the alloys, compression deformation will be applied to some parts and the possible influence on the corrosion behaviour will be specified by the same way. The presence of silicon in the NiMoCr base induces significant modifications in the microstructure (presence of particles particularly rich in Mo and Si) and in corrosion resistance. Globally its presence enhances three times the corrosion current in the active state. The contrary is however observed for the anodic current in the passive state. But the most important is that both alloys are very resistant against corrosion in this {9g/L NaCl; pH=7.4} solution often considered as valuable artificial saliva. Plastic deformation, possibly induced by mastication for the thinnest parts of metallic parts of dental prostheses, seems deteriorating this good behavior in corrosion, but certainly not in great proportions. One can conclude by saying that, for these two alloys, whatever their possible hardening, no significant release of ions, and thus corresponding induced allergy, is to be feared.

Fichier principal
Vignette du fichier
100 POSTER Eurocorr2016Montpellier PB PB.pdf (375.31 Ko) Télécharger le fichier
Origine Fichiers produits par l'(les) auteur(s)
Licence

Dates et versions

hal-03289536 , version 1 (17-07-2021)

Licence

Identifiants

  • HAL Id : hal-03289536 , version 1

Citer

Princilia Billy, Patrice Berthod. Influence of the chemical composition and of the hardened state of four cast Ni-based and Co-based cast alloys on their behaviour in corrosion by an artificial saliva. Part 1: Case of the nickel alloy studied using stationary electrochemical techniques and EIS. Eurocorr 2016, Sep 2016, Montpellier, France. ⟨hal-03289536⟩
63 Consultations
91 Téléchargements

Partager

  • More