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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

Effect of age hardening on corrosion resistance and hardness of CoCrMo alloys used in dental engineering

Dobrzański L., Reimann Ł., Krawczyk C.

Archives of Materials Science and Engineering

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2012

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Vol. 57, nr 1

5-12

EN

Purpose: The goal of the study is to research the effect of various time of ageing on corrosion resistance, hardness and structures of Remanium 2000+ Co-Cr-Mo alloys used in prosthodontia. Design/methodology/approach: To investigation was prepared mould, cast in 1430°C and realized the heat treatment: solutioning in 1250°C by 3 hours and then ageing in 850°C by 4, 8, 16 and 24 hours. Electrochemical corrosion examination were made in water center which simulated artificial saliva environment. The evaluation of breakdown potential was realized by recording of anodic polarization curves with use the potentiodynamic methods. Corrosion resistance test were carried out at room temperature and use of the VoltaLabŽ PGP201 system for electrochemical tests. Hardness test were obtained by use the microhardness FM ARS 9000 FUTURE TECH with load 1 kg. Structure observation was made after surface preparation: grinding, polishing and etching by light microscope LEICA MEF4A with the magnification 500x. Findings: The age hardening for Co-Cr-Mo alloys is one of the possible method which effect in forming the hardness. The highest value of hardness were obtain for specimen which was ageing with the longer time. Research alloy characterized dendritic crystals in structure for all realized heat treated process. At specimen after the longer ageing was observed the most of discontinuous precipitation and stacking faults in compare with specimen ageing by 4 hours. The age hardening doesn’t influenced much on electrochemical results and only the open circuit potential changed by decreased while increased ageing time. The values of breakdown potential and repassivation potential kept at a constant level. Practical implications: Research material is used on dentures so it’s demand that their characterized corrosion resistance and result of this work make up an information on what heat treatment parameters may be pay attention for CoCrMo alloys. Originality/value: The paper present effect of age hardening especially the ageing time, on the most important criteria of CoCrMo alloys use in dental engineering.

3

Struktura i własności mechaniczne modyfikowanych stopów CoCrMo do zastosowań w protetyce stomatologicznej

Beer K., Walczak M.

Engineering of Biomaterials

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2011

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Vol. 14, no. 106-108

110--115

PL

Większość klinicznych niepowodzeń w przypadku protez stomatologicznych związana jest przede wszystkim z techniką wytapiania i odlewania oraz ilością użytego do wsadu stopu już raz przetopionego. W pracy dokonano analizy wpływu ilości materiału z recyklingu na właściwości mechaniczne i strukturę stomatologicznego stopu CoCrMo. Zastosowano metodę odlewania odśrodkowego, oraz jednokrotne przetopy o składzie wyjściowym odpowiednio 0, 25, 50, 75 i 100% złomu. Przeprowadzono statyczną próbę rozciągania, pomiar mikrotwardości, analizę mikrostrukturalną oraz obserwację SEM przełomów. Stwierdzono, że własności mechaniczne wszystkich przetapianych stopów są gorsze niż stopu czystego, zakupionego u zagranicznego producenta. Mikrostruktura przełomów przetapianych stopów z zawartością złomu powyżej 50% jest bardziej niejednorodna i w strukturze dendrytycznej widoczna jest większa ilość mikropęknięć. Podczas zrywania próbek zarejestrowano wyraźne obniżenie granicy plastyczności i wytrzymałości tych stopów w próbach zrywania w porównaniu z próbkami ze stopów zawierających mniejszą ilość materiału z recyklingu.

EN

The majority of clinical failures in the case of dental prostheses is associated primarily with the technique and the amount of remelted alloy used for the casting. The majority of clinical failures in the case of dental prostheses is associated primarily with the technique of remelting and casting, and quantity of the once remelted alloy used for the batch. The paper analyzes the impact of the amounts of recycled material on the mechanical properties and structure of dental alloy CoCrMo. The centrifugal casting method has been applied and remelted alloys with output composition of 0, 25, 50, 75 and 100% of scrap respectively. The static tensile test, microstructural analysis and SEM observation as well as microhardness test have been conducted. These all tests show that the mechanical strength of all remelted alloys is worse than the strength of the fine alloy, purchased from a foreign manufacturer. The microstructure of breakthroughs of the remelted alloys containing more than 50% of scrap is more heterogeneous and a higher amount of microcracks is visible in the dendritic structure. When the samples were tested in the static tension test, the significant decrease in the yield strength and the tensile strength of these alloys during these static tension tests in comparison to the samples of alloys containing lower amount of the recycled material were observed.