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The effect of heat treatment on the microstructure and properties of the corrosion resistance of the prosthetic alloy Wironit ExtraHart (Co-Cr-Mo)

Augustyn-Nadzieja J., Pełka S., Loch-Zawrotniak J.

Metallurgy and Foundry Engineering

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2018

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Vol. 44, no. 4

181--193

EN

The presented study performs an analysis of the effect of thermal treatment on the microstructure and corrosion resistance of the commercial prosthetic alloy Wironit ExtraHart (Co-Cr-Mo). Experiments of thermal treatment, homogenization, oversaturation as well as oversaturation with ageing of the alloys were carried out. Metallographic tests, hardness measurements, EDS analyses and electrochemical investigations were performed. For the examined samples, the corrosion potential (OCP) and polarization curve (LSV) were determined, based on which the corrosion properties in the simulated solution of artificial saliva were established. The results of the obtained tests made it possible to evaluate the effect of the performed thermal treatment on the changes in the properties (hardness) as well as the microstructure and corrosion resistance of the examined alloy Co-Cr-Mo.

PL

W pracy dokonano analizy wpływu obróbki cieplnej na mikrostrukturę i odporność korozyjną komercyjnego stopu protetycznego Wironit ExtraHart (Co-Cr-Mo). Przeprowadzono eksperyment obróbki cieplnej stopów, wyżarzania ujednorodniającego, przesycania i przesycania ze starzeniem. Wykonano badania metalograficzne, analizę EDS oraz badania elektrochemiczne. Dla badanych próbek wyznaczono potencjał korozyjny (OCP) oraz krzywą polaryzacji (LSV), na podstawie których określono właściwości korozyjne w symulowanym roztworze sztucznej śliny. Wyniki otrzymanych badań pozwoliły stwierdzić wpływ przeprowadzonej obróbki cieplnej na zmiany własności (twardość) i mikrostrukturę oraz odporność korozyjną badanego stopu Co-Cr-Mo.

2

Kinetics of pearlite spheroidization

Matusiewicz P., Augustyn-Nadzieja J., Czarski A., Skowronek T.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 1

231--234

EN

The pearlite spheroidization in Fe-0.76%C high purity steel was investigated. The samples of a coarse pearlite microstructure were isothermal annealed at 700, 680, 660, 640 and 620°C for various times, up to 800 hours. For quantitative description of the spheroidization process stereological parameter, SV (ferrite/cementite interface surface density) was used. The activation energy 104.8±11.4 kJ/mol was found for the spheroidization process. This value shows good agreement with the activation energy for iron and carbon diffusion along a ferrite/cementite interface, so the coupled interface diffusion is the rule-controlling process.

3

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

Augustyn-Nadzieja J., Łukaszczyk A., Loch J.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 1

411--418

EN

The 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 Cr23C6 type 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.