Corrosion of galvanic pairs of Co-Cr alloys with high-copper silver amalgam using Mansfeld formulas

In the restoration of lost or damaged dental pieces, different alloys are frequently used, leaving the mouth exposed to electrical currents that circulate through saliva and dental fluids. In the present work, electrochemical methods are used to determine the corrosion rate of galvanic pairs of a high copper silver amalgam with Co-Cr dental alloys in artificial saliva. It is observed that when the difference in corrosion potentials of dissimilar alloys are small (less than 100 mVecs), Evans diagrams do not give good results, so the Mansfeld correction formulas must be used. Thus, it is found that the most resistant to corrosion is the pair formed between the amalgam and the bulk Co-Cr alloy (PG1,3) and that the corrosion products released in greater quantity to the electrolyte are those that contain ions of Co, Cr, Ag, Sr and Cu. Keywords: Corrosion, dental alloy, polarization curve, artificial saliva, galvanic pair

Corrosion of galvanic couplings of Ni-Cr and Co-Cr alloys with Ti-6Al-4V in artificial saliva using electrochemical methods

In this work, the open-circuit corrosion potentials of the alloys studied in aerated artificial saliva were determined; in the same solution, the potentiodynamic polarization curves of said alloys have been drawn. The corrosion potentials and current intensities of the galvanic coupling of the Ti-6Al-4V alloy with the Co-Cr and Ni-Cr alloys were determined using the Evans method, finding that the galvanic couples more resistant to corrosion in the electrolytic medium considered are those formed between the Ti alloy and the Co-Cr alloys; the least resistant are those formed between Ti alloy and Ni-Cr alloys. The corroded surfaces of the seven alloys considered in this work were also studied, and by EDAX the corrosion products due to the ions detached in the electrolytic medium were analyzed. Keywords: Galvanic couplings, dental alloys, Co-Cr, Ni-Cr, corrosion

Corrosion of galvanic pairs of dental alloys copper base with silver amalgams in artificial saliva

Galvanic corrosion is a metal dissolution process that occurs when two metals of different electrochemicalpotential are immersed in an electrolyte causing electrical currents between the metals through the conductingmedium. To restore lost or damaged teeth, different alloys are used, leaving the mouth exposed to electricalcurrents that circulate through saliva and dental fluids. In the present work, the potentials and densitiesof corrosion currents of galvanic pairs of silver amalgams and copper base dental alloys were determinedsimultaneously using potenciodynamic methods, finding that the most resistant to corrosion are the pairsformed by silver amalgams of high copper and Cu - Zn alloys, and that the corrosion products released ingreater quantity in the electrolytic medium are formed by Hg, Cu, Zn and Ni ions.Keywords. Corrosion, dental alloy, polarization curve, artificial saliva, galvanic pair