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The effect of repeated heating on corrosion resistance, hardness and microstructure of a Co-Cr-W prosthetic alloy

Rzepkowska M., Burnat B., Pietnicki K., Skrzypek S., Klimek L.

Journal of Achievements in Materials and Manufacturing Engineering

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2020

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Vol. 99, nr 2

64--71

EN

Purpose: of this article is to present the results of tests carried out on the impact of repeated heating on the corrosion resistance of a Co-Cr-W prosthetic alloy. Design/methodology/approach: The study used samples prepared in a manner analogous to the production of a dental prosthesis. The effect of three and six-time heating of the material on its properties such as corrosion resistance, microstructure and material hardness were carried out. Findings: Repeated heating of the chromium-cobalt alloy has no significant effect on the polarization resistance and the potentiodynamic characteristics of the material. The introduction of heating in alloy treatment results in an increase in the hardness of the material, however, the number of annealing cycles does not affect this feature significantly. Samples subjected to different amounts of thermal treatments have different microstructure; it should be assumed that this will change the mechanical properties. Research limitations/implications: Microstructure tests carried out after electrochemical corrosion tests showed changes in the microstructure of samples subjected to subsequent annealing. The tests of material hardness and corrosion did not show any significant differences that may result from differences in structure, therefore further tests characterizing the physical properties of the material will be carried out. Originality/value: The article is a description of preliminary research on the impact of multiple annealing used in dental prosthetics on the properties of metallic material. Further work will be carried out to identify the properties that may be affected by the indicated changes in microstructure.

2

Effect of the abrasive blasting treatment on the quality of the pressed ceramics joint for a metal foundation

Pruszczyńska E., Pietnicki K., Klimek L.

Archives of Materials Science and Engineering

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2016

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Vol. 78, nr 1

17--22

EN

Purpose: Despite the increasing number of new advanced materials and constructions in prosthetics, ceramic crown and bridges with a metal foundation are still popular among patients. Facing ceramics can be applied on the metal foundation by the pressing or firing method. One of the more frequent damages is the chipping of the facing ceramics from the metal foundation. In order to improve the quality of the joint between the metal foundation and the facing ceramics, the metal surfaces usually undergo abrasive blasting treatment with the use of different treatment parameters, such as the working pressure and the grain size of the abrasive material. Design/methodology/approach: The study presents the research of the effect of the working pressure during pressing on the quality of the metal-pressed ceramics joint. The selection of the abrasive blasting parameters was made based on the earlier studies of the strength of ceramics fired on metal. For the treatment, 110 μm grain and 0,2; 0,4; 0,6 Mpa pressures were applied. After the ceramics pressing process, the samples underwent shear strength tests. Findings: The obtained results were much lower than in the case of a similar joint but with fired ceramics, and they did not meet the requirements of the respective standards. The applied treatment pressures did not affect the strength of the joint. Such results can be explained by the fact that the metal foundation exhibited insufficient roughness after the treatment. While, in the case of the fired ceramics, the gains size 110 μm was optimal, in the case of the pressed ceramics, of a higher viscosity, the ceramics flow did not sufficiently fill the surface irregularities, which caused a lower joint strength. Originality/value: This results from the fact that the surface treatment parameters used before the ceramics firing process cannot be directly transferred to the case of the pressed ceramics.

3

Wpływ zawartości węgla i azotu w powłokach Ti(C,N) na ich wybrane właściwości mechaniczne

Banaszek K., Pietnicki K., Klimek L.

Obróbka Plastyczna Metali

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2015

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T. 26, nr 1

33-46

PL

Stopy metali nieszlachetnych stosowane w protetyce i ortodoncji na różnego rodzaju uzupełnienia i aparaty mogą powodować niekorzystne odpowiedzi organizmu. Aby temu zapobiec stosuje się różnego rodzaju modyfikacje warstw wierzchnich oraz pokrycia ochronne. Najczęściej stosowanymi są tlenki, węgliki i azotki metali. Spośród tych ostatnich na szczególną uwagę zasługują węgliki i azotki tytanu, charakteryzujące się dobrymi właściwościami mechanicznymi i dużą odpornością na korozję. Celem niniejszej pracy było zbadanie wybranych właściwości (moduł sprężystości, twardość, przyczepność) powłok Ti(C,N) na stopach protetycznych w zależności od udziału w nich węgla i azotu. Badaniom poddano próbki w kształcie walców ze stopu protetycznego typu Ni-Cr pokrytego powłokami Ti(C,N) o różnej zawartości węgla i azotu w warstwie, poczynając od czystych powłok TiN do czystych TiC. Powłoki osadzano metoda rozpylania magnetronowego. Na tak otrzymanych próbkach wykonano badania twardości i modułu sprężystości metodą nanoindentacji oraz przyczepności zgodnie z normą VDI 3198. W wyniku przeprowadzonych badań stwierdzono, że wzrost zawartości węgla w powłoce Ti(C,N) powoduje zarówno wzrost twardości od 20 GPa (TiN) do 34 GPa (TiC), jak i modułu sprężystości od 272 (TiN) do 382 (TiC). Przyczepność wszystkich badanych powłok do podłoża metalicznego była zadawalająca i mieściła się w klasie HF1 wzorca normy. W żadnym przypadku nie odnotowano delaminacji powłok, a tylko pęknięcia w okolicy odcisku, przy czym widoczne one były dopiero przy dość znacznym powiększeniu (1000x). Podsumowując przeprowadzone badania, można stwierdzić, że powłoki typu Ti(C,N) na protetycznym stopie Ni-Cr są zadowalające z punktu widzenia zastosowania ich jako ochronne na elementach protetycznych i ortodontycznych.

EN

Non-precious metal alloys used in prosthetics and orthodontics for various kinds of restorations and apparatuses can cause disadvantageous responses of the body. In order to prevent this, different surface layer modifications as well as protective coatings are applied. Among the most frequently used, we can name metal oxides, carbides and nitrides, among which titanium carbides and nitrides are especially worth-mentioning, as they characterize in good mechanical properties and high corrosive resistance. The aim of this work was to examine selected properties (modulus of elasticity, hardness, adhesion) of Ti(C,N) coatings applied on prosthetic alloys, depending on the carbon and nitrogen content. The tests involved the use of cylinder-shaped samples made of a Ni-Cr-type prosthetic alloy coated with Ti(C,N) coatings of different carbon and nitrogen contents in the layer, from pure TiN coatings to pure TiC coatings. The coatings were deposited by the magnetronic sputtering method. The samples obtained in this way then underwent hardness and modulus of elasticity tests by the nano-indentation method as well as adhesion tests according to the VDI 3198 standard. The results of the examinations showed that an increase of the carbon content in the Ti(C,N) coating causes an increase of both the hardness, from 20 GPa (TiN) to 34 GPa (TiC), and the modulus of elasticity, from 272 (TiN) to 382 (TiC). The adhesion of all the examined samples to the metal substrate was satisfying and was within the range of the HF1 grade of the standard’s model. None of the cases exhibited coating delamination – only fractures in the vicinity of the indentation, which were visible only at quite a large magnification (1000x). To sum up the performed tests, we can state that Ti(C,N)-type coatings applied on a prosthetic Ni-Cr alloy are satisfying from the point of view of their protective application for prosthetic and orthodontic elements.

4

Modelowanie wytrzymałości połączenia podłoża metalowego z ceramiką dentystyczną w zależności od parametrów uprzedniej obróbki strumieniowo-ściernej

Pietnicki K., Wołowiec-Korecka E., Klimek L.

Mechanik

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2015

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R. 88, nr 8-9CD1

266--269

PL

W pracy zbadano możliwości zastosowania sieci neuronowych do przewidywania wytrzymałości połączenia metal – ceramika w zależności od zastosowanych parametrów uprzedniej obróbki strumieniowo-ściernej. Na podstawie badań doświadczalnych opracowano zestaw 180 wzorców uczących a następnie uczono grupę 150 losowo wytypowanych sieci neuronowych, w celu doboru sieci o najlepszym dopasowaniu. Zaprojektowana sztuczna sieć neuronowa symuluje prawidłowo rzeczywistą zależność występującą podczas obróbki strumieniowo-ściernej i może być stosowana do określenia wytrzymałości połączenia metalu z ceramiką.

EN

The study investigated the possibility of using neural networks to predict the strength of the connection metal - ceramic depending upon the parameters of the prior blasting. On the basis of experiments developed a set of 180 patterns of learning and then were taught a group of 150 randomly selected neural network, for the selection of the network with the best match. Designed an artificial neural network simulates correctly the real dependence, produced during blasting and it can be used to determine the bond strength metal with ceramics.

5

The effect of abrasive blasting on the strength of a joint between dental porcelain and metal base

Pietnicki K., Wołowiec E., Klimek L.

Acta of Bioengineering and Biomechanics

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2014

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Vol. 16, no. 1

63--68

EN

This paper presents the effect of selected parameters of abrasive blasting on the strength of a joint between dental porcelain and metal base. Experiments were conducted for different grain sizes of abrasive material and different blasting angles, with a constant blasting pressure. InLine dental porcelain was fused on samples of cobalt-chromium alloy following abrasive blasting; they were subsequently subjected to shearing forces on a testing machine. The fractures were observed under an electron scanning microscope in order to determine the character and course of fracturing. Strength tests showed that the grain size of abrasive material was a parameter with the greatest effect on the strength. The best effects were achieved for samples subjected to abrasive blasting with material with grain size of 110 μm. No statistically significant differences were found for the strength of samples worked at different angles. The results of the fractographic examinations have shown that in all the samples, fracturing occurred mainly along the porcelain–metal boundary, with few cases of fracturing through porcelain.

6

Modeling of the number of stubble stuck elements after abrasive jet machining-processing

Pietnicki K., Wołowiec E., Klimek L.

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 3

51-54

EN

Sticking of abrasive grains into the surface is the effect of abrasive jet machining processing. For prosthetic works burnt the clay, it may deteriorate the quality of metal-clay connection. Parameters of sandblasting have the significant influence on the amount of stubble elements stuck into the base. The aim of the research is examining possibilities of applying neuron networks for modeling this process. Examples were sandblasted using alternating parameters (pressure of working factor, angle of sandblasting, size of grains). As a next the amount of stubble elements stuck into the base were calculated. Study results allowed to work out a set of 180 standardized teaching patterns. Next, a group of 150 randomly selected neuron networks was submitted to teaching process. The aim was to select net architecture with the highest adjustment for discussed issue. Finally, a MLP (Multi Layer Perception) was chosen. Training process of the net involved presentation of process entrance parameters to the net, followed by presentation of researched proportional partaking of stuck elements. In following training cycles the error was decreasing systematically. After finishing the training, the average medium error between the real measurement and the one anticipated by the net was about 5 per cent. Additional number of abrasive jet machining processing was done to verification experiments. As the study shows, designed artificial neuron net stimulates real dependencies appearing during abrasive jet machining-processing in a proper way and can be used for estimating proportional part of grains stuck into base after this processing. It turns out that this phenomenon can be modeled, and its model can be used in a practical way without using mathematical or physical equations.