The work presents the results of microscopic tests of two alloys: Co-Cr-Mo and Co-Cr-W-Mo, together with a quantitative local analysis of the chemical composition, with the use of an electron microprobe X-ray analyzer EDS. Corrosion resistance tests were also performed on the alloys, in the artificial saliva environment. The microstructure of the examined alloys was of the dendrite type. An eutectic consisting of alloy carbides and a cobalt austenite was observed in the interdendritic spaces. The dendritic matrix was a solid solution of chromium, molybdenum and carbon in cobalt (γCo), and the precipitates present in the interdendritic spaces were rich with Cr and Mo -in the case of Co-Cr-Mo -and with W and Mo -in the case of Co-Cr-W-Mo. The analyzed materials exhibited a similar progress of polarization curves. The obtained currentless potential values and the wide passivation area of those alloys made it possible to conclude their high corrosion resistance in the examined environment.Keywords: dental alloys, cobalt matrix alloys, corrosion resistance W pracy przedstawiono wyniki badań mikroskopowych dwóch stopów: Co-Cr-Mo i Co-Cr-W-Mo wraz z ilościową analizą punktową składu chemicznego przy wykorzystaniu mikroanalizatora rentgenowskiego EDS. W ramach pracy wykonano również badania odporności korozyjnej stopów w środowisku sztucznej śliny. Mikrostruktura badanych stopów miała budowę dendrytyczną. W przestrzeniach międzydendrytycznych występowała eutektyka składająca się z węglików stopowych i austenitu kobaltowego. Osnowę dendrytyczną stanowił roztwór stały chromu, molibdenu i węgla w kobalcie (γCo), zaś wydzielenia występujące w obszarach międzydendrytycznych były bogate w Cr i Mo -w przypadku stopu Co-Cr-Mo oraz W i Mo -w przypadku stopu Co-Cr-W-Mo. Analizowane materiały wykazywały zbliżone przebiegi krzywych polaryzacji. Z otrzymanych wartości potencjału bezprądowego oraz na podstawie szerokiego obszaru pasywacji tych stopów można wnioskować o ich wysokiej odporności korozyjnej w badanym środowisku.
The purpose of this article was to characterize the corrosion behaviour and compare two biomedical titanium alloys (Ti-6Al-4V and Ti-10Mo-4Zr) in an artificial saliva solution (MAS) containing lactic acid and hydrogen peroxide (H O 2) used in dentistry. The addition of these two compounds simulate the situation, where the alloy is implanted in the human body and hydrogen peroxide is generated by the inflammatory reaction and lactic acid is release by bacterial in the oral cavity. Design/methodology/approach: In this studies were used following electrochemical techniques: Open Circuit Potential (OCP), Linear Sweep Voltamperometry (LSV), Chronoamperometry at constant potential and Electrochemical Impedance Spectroscopy (EIS). Electrochemical impedance spectra were carried out at the 0.5 V vs. Ag/AgCl potential. The EIS data were fitted using the ZViev software. Findings: The results presented in the work demonstrate that the titanium alloys have a good corrosion resistance. The corrosion behaviour was determined by surface condition of alloys and presence different chemical compounds in the solution. For Ti-10Mo-4Zr titanium alloy in MAS with different concentration of hydrogen peroxide in anodic domain it was seen more clearly. Research limitations/implications: In the future passive films of both titanium alloys will be investigated by: X-ray photoelectron spectroscopy (XPS) and scanning electron spectroscopy (SEM). Originality/value: The corrosion behaviour of biomedical titanium alloy contains molybdenum and zirconium selected as safe alloying elements for human body is presented and compared to commercial Ti-6Al-4V alloy. The corrosion resistance of the titanium alloys was investigated in the artificial saliva solution with addition of lactic acid and hydrogen peroxide.
The effect of B and microalloying additions of V, V+Ti, V+Nb on austenite grain growth of low alloy steel containing 0.3% C, 1 % Cr and 0.2 % Mo was investigated. As a measure of austenite grain size the mean chord length of austenite grains was assumed. The boron content in investigated steel was in the range of 0 to 0.008 %. The investigations were carried out in austenitising temperature range of 850 to 1100oC. Using the thermodynamic model the contents of undissolved compounds of carbonitride V(C,N) and boron nitride BN were calculated and the effect of undissolved compounds content on austenite grain size was investigated. Obtained results showed, that vanadium content below 0.1 % was ineffective as austenite grain growth inhibitor of boron containing steel and austenite grain size of steel was higher compare to non-alloyed steel. The most effective for decreasing of austenite grains size of boron containing steel was addition of 0.18 % V + 0.03 % Nb
The purpose of this paper was to study the corrosion resistance of Co-Cr and Ni-Cr dental alloys in simulated artificial saliva by means of electrochemical techniques. Co and Ni based alloys are widely used in dental skeletal structures and orthopedic implants such as screws, pins and plater. And recently they have been applied for making stents. The advantages of these alloys include low cost of casting, matching thermal expansion coefficient with the ceramics of metal-ceramic restorations, and acceptable mechanical and tribological properties in vivo. The microstructure of investigated alloys were studied by using optical microscopic observation, X-ray diffraction measurements and Scanning Electron Microscope with X-ray microanalyzer. The mechanical properties were characterized by microhardness tests.
The presented paper studies the effect of the casting technology on the corrosion resistance of Co-Cr-Mo alloy. The investigations were conducted on a commercial alloy with the brand name ARGELOY N.P SPECIAL (Co-Cr-Mo) produced by Argen as well as the same alloy melted and cast by the lost wax casting method performed by a dental technician. The corrosion behavior of the dental alloys in an artificial saliva was studied with the use of the following electrochemical techniques: open circuit potential and voltammetry. After the electrochemical tests, studies of the surface of the examined alloys were performed by means of a scanning electron microscope with an X-ray microanalyzer. The results of the electrochemical studies show that the dependence of the corrosion resistance on the microstructure associated with the recasting process is marginal. The results of the electrochemical studies of the considered alloy clearly point to their good corrosion resistance in the discussed environment.Keywords: cobalt alloys, corrosion resistance, method of wasted wax, microstructureZbadano wpływ technologii odlewania na odporność korozyjną stopu Co-Cr-Mo. Badaniom poddano stop komercyjny o nazwie handlowej ARGELOY N.P SPECIAL (Co-Cr-Mo) firmy Argen oraz ten sam stop przetopiony i odlany przez technika dentystycznego metodą traconego wosku. Zachowanie korozyjne badanego stopu w środowisku sztucznej śliny zostało zbadane przy użyciu technik elektrochemicznych: pomiaru potencjału bezprądowego, woltamperometrii cyklicznej.Po przeprowadzeniu badań elektrochemicznych wykonano badania powierzchni badanego stopu przy pomocy elektronowego mikroskopu skaningowego z mikroanalizatorem rentgenowskim. Wyniki badań elektrochemicznych wskazują, że na odporność korozyjną oraz mikrostrukturę stopu proces powtórnego odlania wpływa jedynie w niewielkim stopniu. Wyniki badań elektrochemicznych rozpatrywanego stopu wskazują jednoznacznie na ich dobrą odporność korozyjną w rozpatrywanym środowisku.
The work presents the results of the studies of Co-Cr-Mo casting alloys used in the production of frame casts of removable dentures, crowns and bridges in dental prosthetics. The studies were performed on four Co-Cr-Mo alloys of different contents of Mo, W and other additives. Electrochemical tests were performed, which aimed at examining the corrosion resistance of the alloys and observing the alloy structure after chronoamperometric tests with the potential in the area of the occurrence of the passive layer breakpoint. The alloy microstructure images after chronoamperometric tests show the presence of non-uniformly distributed general corrosion. Moreover, a project of cobalt alloy casting was elaborated using a ceramic mold casting. Additionally, analysis of the obtained microstructure was performed. The microstructure of the examined alloys was of the dendrite type. This microstructure was chemically inhomogeneous and consisted of an austenitic matrix formed by a solid cobalt solution and chromium in the core dendritic structure.
The high mechanical properties of the Al-Li-X alloys contribute to their increasingly broad application in aeronautics, as an alternative for the aluminium alloys, which have been used so far. The aluminium-lithium alloys have a lower specific gravity, a higher nucleation and crack spread resistance, a higher Young's module and they characterize in a high crack resistance at lower temperatures. The aim of the research planned in this work was to design an aluminium alloy with a content of lithium and other alloy elements. The research included the creation of a laboratorial melt, the microstructure analysis with the use of light microscopy, the application of X-ray methods to identify the phases existing in the alloy, and the microhardness test.
The presented work provides the results of the abrasive wear resistance tests performed on Co-Cr-Mo and Co-Cr-Mo-W alloys with the use of the Miller’s apparatus. The analyzed alloys underwent microstructure observations as well as hardness measurements, and the abraded surfaces of the examined materials were observed by means of electron scanning microscopy. The performed examinations made it possible to state that the Co-Cr alloys characterized in a high hardness, whereas the changes in the mass decrement were minimal, which proved a high abrasive wear resistance.
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