Effect of Remelting of the Ni-22Cr-9Mo Alloy on its Microstructural and Electrochemical Properties

Abstract

AbstractThe Ni-Cr-Mo alloys are used as the alternative for the cobalt alloys in the manufacture of metal prosthetic elements, i.e. crowns, bridges and frame prostheses. The article attempts at a materials science characterization of the nickel-based alloy of the commercial name Argeloy N.P Be-Free by Argen. Within the study, examinations were made on the commercial alloy as well as the alloy which was remelted and cast by the los mould (lost wax) method. Observations of the microstructure were performed with the use of optical and electron scanning microscopy. Also, X-ray structural tests were conducted as well as corrosion resistance tests in an artificial saliva solution (pH = 6,7). It was demonstrated that the examined Ni-22Cr-9Mo alloy characterized in a dendritic structure typical of the cast materials. The X-ray qualitative phase analysis revealed the phase γ'(Ni) in both examined materials, as well as the presence of Cr23C6type carbides and Nb2C, Ta2C (commercial alloy) and NbC, Ta4C0,04(cast alloy) phases. The effect of the alloy’s remelting and the morphology of the passive layer on the corrosion resistance of the Ni-Cr-Mo alloy was examined.The results of the electrochemical tests show that the process of re-casting only slightly affects the corrosion resistance and the microstructure of the considered alloy.The roles of recasting process and the passive film homogeneity on the corrosion resistance of Ni-Cr-Mo dental alloy were reviewed. The results the electrochemical study show that the dependence of corrosion resistance on the microstructure associated with the recasting process is marginal.