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1

Hot Deformation Activation Energy of Metallic Materials Influenced by Strain Value

Schindler I., Opěla P., Kawulok P., Sauer M., Rusz S., Kuc D., Rodak K.

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 1

223--228

EN

Suitable and complete sets of stress-strain curves significantly affected by dynamic recrystallization were analyzed for 11 different iron, copper, magnesium, titanium or nickel based alloys. Using the same methodology, apparent hot deformation activation energy Qp and Qss values were calculated for each alloy based on peak stress and steady-state stress values. Linear dependence between quantities Qp and Qss was found, while Qp values are on average only about 6% higher. This should not be essential in predicting true stress of a specific material depending on the temperature-compensated strain rate and strain.

2

Problemy oceny tłoczności materiałów metalicznych

Hyrcza-Michalska M.

Hutnik, Wiadomości Hutnicze

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2016

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Vol. 83, nr 9

398--400

PL

W artykule przedstawiono problemy oceny tłoczności materiałów metalicznych, których odkształcalność jest ograniczona. Zdefiniowano pojęcie trudno odkształcalnych wsadów do tłoczenia dzięki zestawieniu i usystematyzowaniu przyczyn ograniczających tłoczność. Zaproponowano wytyczne postępowania przy ocenie tłoczności dla tego typu trudno odkształcalnych wsadów. Stosowana metodyka badawcza opiera się o wykorzystanie metod fizycznego i numerycznego modelowania proceu tłoczenia. W badaniach zastosowano systemy automatycznego analizatora odkształceń Auto Grid, a do modelowania numerycznego oprogramowanie ETA/Dynaform. Praca stanowi przekrojową analizę szeregu badań prowadzonych przez autorkę w zespole badaczym Instytutu Technologii Metali Politechniki Śląskiej przez ostatnich kilka lat.

EN

The article presents the drawability evaluation problems of metallic materials, which deformability is limited. There is defined the concept of hard deformable charges for pressing through the statement and systematize the reasons for restricting their drawability. The guidelines for the drawability assessment for such type difficult charges are proposed. The research methodology is based on the use of methods of physical and numerical modeling of the stamping process. Presented study used the automatic strains analyzer Auto Grid and numerical modeling software ETA / Dynaform. This work is a cross-sectional analysis of a series of studies conducted by the author in the research team of the Institute of Metal Technology Silesian University of Technology in the past few years.

3

Materiały stosowane do wytwarzania implantów kości

Janik H., Marzec M.

Przemysł Chemiczny

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2015

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T. 94, nr 2

182-185

PL

Materiały stosowane do wytwarzania implantów kostnych muszą być biokompatybilne, nietoksyczne, bioaktywne oraz wykazywać odpowiednie właściwości mechaniczne, takie jak wytrzymałość na ściskanie, na zginanie oraz sztywność i twardość. Gama stosowanych materiałów jest bardzo szeroka, obejmuje metale, polimery, ceramikę oraz ich kompozyty. Każdy z tych materiałów ma swoje mocne i słabe strony. Praca stanowi przegląd materiałów stosowanych do wytwarzania implantów kości, ze szczególnym uwzględnieniem oferty rynku polskiego.

EN

A brief review, with 24 refs., of metallic, ceramic, polymeric and composite materials.

4

Dawne górnictwo surowców metalicznych rejonu Przybramu

Strzałkowska E.

Przegląd Górniczy

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2014

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T. 70, nr 4

114--118

PL

W artykule przypomniano historię dziejów miasta Przybram, a także poruszono zagadnienia z zakresu dawnego górnictwa rud srebra, cynku i ołowiu w obszarze Brezovych Hor. Omówiono zarys budowy geologicznej tego obszaru oraz krótko scharakteryzowano występujące tu minerały rudne i towarzyszące. Zaprezentowano ponadto dane dotyczące występowania, warunków eksploatacji i wielkości wydobycia rud uranu na tym terenie.

EN

This paper presents the history of the city of Przybram as well as old-time mining issues for silver ore, zinc ore and lead ore in the area of Brezove Hory. The geological structure of this area was discussed and the existing ore minerals and accompanying minerals characterized. Finally, data on the occurrence, exploitation conditions and output size of uran ore were presented.

5

The selected manufacturing problems of the bulk metallic glasses

Pilarczyk W.

Selected Engineering Problems

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2013

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nr 4

139--142

EN

In this article selected problems that occur during the manufacture of bulk metallic glasses have been discussed. A number of different techniques to synthesize bulk metallic glasses (BMG) alloys have been developed. These developments have been occurred in different laboratories, for some specific applications or materials. In this paper the analysis of glass transition factors and the associated technological problems have been presented. The observations and gained experience during the preparation of iron-based and zirconium-based bulk metallic glasses prepared by die pressure casting method were the basis for this elaboration.

6

Improved adhesion and growth of osteoblast-like MG-63 cells in cultures on titanium modified by gold particles

Parizek M., Base T., Hruby M., Lisa V., Bacakova L.

Engineering of Biomaterials

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2013

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Vol. 16, no. 122-123 spec. iss.

77

EN

Metallic materials are important for load-bearing bone implants. The osteointegration of these implants can be improved by appropriate surface modifications. Therefore, we present here a study of the cell growth on titanium surfaces modified with films created from gold microparticles. These particles in the form of microplates or polyhedral microcrystals were deposited on titanium plates from ethanol solutions, dried and annealed with a hydrogen flame. Some samples were additionally modified by polyethylene imine. The materials engendered from these modifications were used to investigate the adhesion and growth of human osteoblast-like MG-63 cells on these surfaces in the DMEM medium with 10% of fetal bovine serum. One day after seeding, the highest number of initially adhered cells was found on the surfaces modified by both types of gold microparticles. This trend was the same three and seven days after seeding. The numbers of cells on pure Ti and Ti modified only with gold particles were significantly higher than on samples which were modified with polyethylene imine. The cell spreading areas projected on the materials were significantly larger in cells on the samples with polyethylene imine modification. However, the shape of these cells was mostly rounded or star-like with thin and long protrusions, while on the materials without polyethylene imine, it was mostly polygonal. The cell proliferation activity was estimated from XTT test, based on the activity of mitochondrial enzymes. This test showed that the proliferation activities of osteoblast-like MG-63 cells of the 3rd and 7th days of the experiment were more pronounced on the samples modified only by gold microparticles. Immunofluorescence showed that the focal adhesion plaques containing vinculin and the fibers containing β-actin were most apparent, more numerous and more brightly stained in cells on Ti modified by gold microplates and gold polyhedral microcrystals, especially in comparison with the corresponding samples modified with polyethylene imine (Fig. 1). Thus, it can be concluded that the modification of titanium samples by both types of gold microparticles enhanced the adhesion and growth of MG 63 cells.

7

Adhesion, growth and differentiation of human osteoblast-like cells on thermally oxidized Ti and TiNb substrates

Bacakova L., Vandrovcova M., Jirka I., Novotna K., Stary V.

Engineering of Biomaterials

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2013

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Vol. 16, no. 122-123 spec. iss.

75--76

EN

Metallic materials are essential for construction of load-bearing bone implants, such as replacements of hip, knee and other joints. For these applications, modern materials used in advanced tissue engineering, e.g. resorbable porous or fibrous polymeric and ceramic scaffolds are mechanically insufficient, even if these materials enable the ingrowth of bone cells and bone tissue formation. Therefore, searching for new metallic materials and their surface modifications improving their biocompatibility and osseointegration is still desirable. As first metallic materials for bone implantation, AISI 316L stainless steel and Co-Cr alloys were used. In the 1950’s, the Ti-6Al-4V alloy was developed. These materials are still frequently used for construction of implants because of their relatively low price [1]. However, these materials are biomechanically incompatible with the bone tissue, because their Young’s modulus is markedly higher (110-220 GPa) than that of the bone (10-40 GPa). Implants with high stiffness take over a considerable part of load from the bone. This phenomenon, referred as “stress-shielding effect”, can then cause the bone resorption and loosening of the implant [1]. Also chemical compositions of the mentioned metallic materials limit their biocompatibility, because they contain harmful elements as V, Al, Co and Cr, which can act as cytotoxic, catabolic, immunogenic or even carcinogenic agents [2,3], and can also cause serious neurological problems [4]. Due to these adverse reactions, new types of Ti-alloys have been developed, namely low-rigidity β-type Ti alloys, containing non-toxic and non-allergenic elements (Nb, Ta, Zr etc.) and having good mechanical properties and workability [4,5]. The goal of this study was to evaluate the adhesion, growth and differentiation of osteoblast-like MG-63 and Saos-2 cells on titanium-niobium alloys after their surface modification by thermal oxidation at two different temperatures (165°C and 600°C). Pure titanium (treated at 165°C and 600°C) and polystyrene culture dishes (PS) were used as control materials. Possible immune activation of the cells was tested by the levels of TNF-alpha secreted to the cell culture media by murine macrophage-like RAW 264.7 cells cultured on the tested materials. On samples treated at 165°C, the number of initially adhered MG-63 and Saos-2 cells was on an average higher on TiNb than on Ti or PS. On day 3 after seeding, the trend of the cell numbers remained similar, with the highest cell density found on TiNb. Similar results were obtained on samples treated at 600°C, where the difference in cell number between TiNb and Ti samples became more apparent. This cell behavior could be attributed to a less negative zeta potential on TiNb samples. In samples treated at 165°C, the zeta potential of TiNb surfaces was on the average less negative than on Ti surfaces, but this difference was not significant. However, in samples treated at 600°C, this difference became much more pronounced, which was probably due to the formation of T-Nb2O5 phase on the surface of the TiNb samples. This phase was of a crystalline structure, while at 165°C, the structure of Nb2O5 was amorphous. In addition, both Ti and TiNb samples treated at 600°C contained rutile, while the samples treated at 165°C contained anatase in their surface layer. It has been shown that rutile films deposited on PEEK enhanced the adhesion and growth of osteoblasts more than anatase films [6]. This phenomenon was explained by an increase in the material surface wettability, and particularly to the presence of –OH- groups on the rutile films. The expression of collagen I and osteocalcin, i.e. an early and late marker of osteogenic cell differentiation, respectively, was higher on Ti than on TiNb samples, and this difference was more apparent in samples treated at 165°C. At the same time, no considerable immune activation of the cells on all tested samples was found. The production of TNF-α by RAW 264.7 cells was very low in comparison with cells grown in the presence of bacterial lipopolysaccharide, and also significantly lower than on untreated samples. These results indicate that TiNb substrates increased the proliferation of human bone cells, while pure Ti rather supported the cell differentiation. The effect on cell proliferation was more apparent in samples treated at the higher temperature (600°C), while the effect on cell differentiation was more pronounced at the lower temperature (165°C). None of the tested samples induce significant cell proinflammatory activation. Thus, all tested samples are suitable as carriers for bone cells; only an appropriate application (i.e., requiring either proliferation or quick differentiation of osteogenic cells) should be selected.

8

Korozja tworzyw metalicznych i ochrona przed korozją ze szczególnym uwzględnieniem cynkowania zanurzeniowego (ogniowego) żeliwa

Stanuch I.

Ochrona przed Korozją

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2012

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nr 10

442-448

PL

Z uwagi na wielość i różnorodność zagadnień dotyczących pojęcia korozji istnieje wiele aspektów klasyfikacji tego zjawiska w odniesieniu do przyjętego kryterium. Celem artykułu jest próba usystematyzowania tej złożonej tematyki w spójną całość. Wyeksponowano również aspekt cynkowania zanurzeniowego (ogniowego) żeliwa ciągliwego białego i sferoidalnego oraz kinetykę wzrostu warstwy dyfuzyjnej.

EN

Due to the number and variety of queslions relating to ihe notion of corrosion, many aspects arę taken into consideration when attempting to classijy ihis phenomenon based on a given criterion. The paper attempts to systematise the complex concept of corrosion into a coherenl whole. The aspect of hot-dip galvaizing of white and spheroidal malleable cast iron is presented and tlie kinetics of the growth of the diffusion layer are also shown.

9

Silicon influence on the microstructure formation at cooling rates lower than the critical rate

Pacyna J.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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Vol. 54, nr 2

178--184

EN

Purpose: On the bases of fundamental research [1], on the silicon influence on the kinetics of phase transformation of undercooled austenite in model ferrous alloys with carbon of a weak background of other alloying elements, it was found that up to the Si content of 1 mass % the steel hardenability decreases. The time before the start of the ferrite precipitation decreases as well as the time before the start of the pearlite and bainite formation. On the other hand in model ferrous alloys with carbon of a strong background of other elements, also in the range to app. 1 Si %, the time before the start of the ferrite precipitation and bainite formation is insignificantly prolonged (hardenability increases minimally), while the location of the start of the pearlitic transformation remains practically the same. This observation, being a part of designing the ferrous alloys structure, can be successfully utilised, among others, in steels for working rolls for plates cold-rolling. Due to that in these expensive tools we are able to soften the influence of the structural notch, which is formed - at a certain depth - by the upper bainite layer, in steels without silicon additions. Design/methodology/approach: Dilatometric investigations were performed using a DT 1000 dilatometer of a French company Adamel. Findings: An addition of 1 mass % of silicon causes a gradual vanishing of the steel bainitisation, being the bainite slipping in ‘under pearlite’, due to which the austenite, at continuous cooling, will be at first transformed into pearlite, on its grain boundaries, and only later - inside grains - into bainite. Even if it is the upper bainite its location inside grains, within the pearlite envelope, is less dangerous for the crack resistance than its location on grain boundaries. Research limitations/implications: These observations can be utilized for steels in which the bainitic transformations are shifted in the direction of shorter times (e.g. in chromium - molybdenum steels). Especially when this is the upper bainite known for its low crack resistance. Practical implications: Due to this work in expensive tools we are able to soften the influence of the structural notch, which is formed - at a certain depth - by the upper bainite layer, in steels without silicon additions. Originality/value: Details descriptions of influence of the Si content on the kinetics of phase transformations during cooling in model ferrous carbon alloys with a weak background and also strong background of other alloying elements.

10

Analyses of the melt cooling rate in the melt-spinning process

Karpe B., Kosec B., Bizjak M.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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Vol. 51, nr 2

59--66

EN

Purpose: Rapid solidification (RS) of metallic melts is important for the development of the advance metallic materials, because enables the production of new alloys with superior properties according to conventionally treated alloys. In practice it turned out, that single roll melt spinning process has one of the highest melt cooling rates among all continuous casting processes. But, because very short solidification time and movement of the melt and substrate, melt cooling rate is very difficult to measure with confidence. Primary goal of our work was to determine the limits of cooling rate over the ribbon thickness and to outline, which property or typical feature of the process has the greatest influence on cooling rate of the melt. Design/methodology/approach: On the basis of developed mathematical model, a computer program was made and used for melt cooling rate calculation in the melt-spinning process. Findings: The calculations show that distance from the contact surface in relation to the thermal properties of the melt, chilling wheel material and contact resistance between metal melt and chilling wheel have the greatest influence on melt/ribbon cooling rate. In the case of continuous casting, significant “long term” surface temperature increase may take place, if the wheel is not internally cooled. Research limitations/implications: Influence of the melt physical properties, chill wheel material, contact resistance and cooling mode of the chill wheel on melt cooling rate are outlined. Practical implications: Practical limits of melt cooling rate over ribbon thickness are outlined and directions for the chill wheel cooling system design are indicated. Originality/value: Comparison between cooling rates calculated at various thermal resistance assumptions of particular constituents is outlined. New method for determining contact resistance through variable heat transfer coefficient is introduced which takes into account physical properties of the casting material, process parameters and contact time/length between metal melt/ribbon and substrate and enables cooling rate prediction before the experiment execution. In the case of continuous casting, heat balance of the melt-spinning process is calculated and influence of the chill wheel cooling mode on cooling rate of metallic ribbon is analyzed.

11

Potential activation of the immune system on metallic materials for bone implants

Stranavova L., Bacakova M., Novotna K., Bacakova L., Fencl J.

Engineering of Biomaterials

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2012

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Vol. 15, no. 116-117 spec. iss.

130--131

EN

Titanium and stainless steel are metallic materials that have been in use for a long time in orthopedics, traumatology and stomatology. These metals are strong, corrosion-resistant and biocompatible. However, metallic materials have some disadvantages in comparison with the natural bone, particularly their relatively high specific weight and toughness. For example, the Young's modulus of AISI316L stainless steel, Co-Cr alloys and Ti-6Al-4V alloy, i.e. materials frequently used for implantation into bone, ranges between 110-220 GPa, while the Young's modulus of bone tissue is 10-40 GPa [1]. In addition, these metals can release cytotoxic, allergenic and immunogenic ions, which can affect their biocompatibility [2, 3]. Implantation is a special type of transplantation process, in which the implant is inserted into the body, usually in order to replace an irreversibly damaged tissue. However, the immune system recognizes the implant as a foreign substance and attacks it with its effector mechanisms. Just as it can reject other types of transplants, the immune system can reject an artificial implant. To prevent rejection of an implant, it is important to study the potential activation of the immune system. This study has investigated the biocompatibility of samples made of pure titanium (according to quality standard ISO 5832-2) and corrosion-resistant steel (quality standards ISO 5832-1 and AISI 316L), obtained from Beznoska Ltd. (Kladno, Czech Republic), and the potential activation of the immune system by these materials. In addition to Fe, the steel samples contained C (max. 0.025 wt.%), Si (0.6 wt.%), Mn (1.7 wt.%), P (max. 0.025wt.%), S (max. 0.003 wt.%), Cr (17.5 wt.%), Ni (13.5 wt.%), Mo (2.8 wt.%), and Cu (max. 0.1 wt. %). The materials were used in the form of square samples (9x9 mm or 30x30 mm, thick¬ness 1 mm). Both the Ti samples and the steel samples were ground with SiO2. The surface of the steel samples was then treated by polishing with Al2O3 paste (grain size up to 1 um), while the surface of the Ti samples, i.e. a material not suitable for polishing, was finished by brushing using another type of Al2O3 paste with slightly larger grains. Thus, the surface of the steel samples was finally smoother and glossy, while the Ti surface was rougher and matte. For the in vitro biocompatibility tests, human osteoblast-like MG 63 cells (European Collection of Cell Cultures, Salisbury, UK) were used. The smaller samples (9x9 mm) were inserted into polystyrene 24-well cell culture plates (TPP, Trasadingen, Switzerland; well diameter 1.5 cm). Each well contained 25 000 cells (approx. 14 150 cells/cm2) and 1.5 ml of Dulbecco's Modified Eagle Minimum Essential Medium (DMEM; Sigma, USA, Cat. No. 10270-106) supplemented with 10% foetal bovine serum (FBS; Gibco, Cat. No. 10270-106) and gentamicin (40 /jg/ml, LEK, Slovenia). These samples were used for evaluating the size of the cell spreading area (day 1), and for evaluating cell shape and cell viability (days 1, 4 and 7 after seeding). The size of the cell spreading area was measured using Atlas Software (Tescan Ltd., Brno, Czech Republic). The viability of the cells was determined by the LIVE/ DEAD viability/cytotoxicity kit for mammalian cells (Invitrogen, Molecular Probes, USA). The larger samples (30x30 mm) were inserted into GAMA polystyrene dishes (diameter 5 cm; GAMA Group Joint-Stock Company, Ceske Budejovice, Czech Republic) and seeded with 300 000 cells/dish (approx. 15 300 cells/cm2) suspended in 9 ml of the above mentioned culture medium. These samples were used for evaluating the cell number on days 1, 4 and 7 after seeding, using a Beckman Vi-CELL XR Cell Analyser automatic cell counter. For the in vitro analysis of markers of osteogenic differentiation and cell immune activation, human osteoblast-like MG 63 cells (European Collection of Cell Cultures, Salisbury, UK) were used. The samples (9x9 mm) were inserted into polystyrene 24-well cell culture plates (TPP, Trasadingen, Switzerland; well diameter 1.5 cm). Each well contained 25 000 cells (approx. 14 150 cells/cm2) and 1.5 ml of Dulbecco's Modified Eagle Minimum Essential Medium (DMEM; Sigma, USA, Cat. No. 10270-106) supplemented with 10% foetal bovine serum (FBS; Gibco, Cat. No. 10270-106) and gentamicin (40 jg/ml, LEK, Slovenia). The cells were cultured for 1, 4, or 7 days at 37°C in a humidified atmosphere of 5% of CO2 in the air. On day 4 after seeding, the medium was changed; one half of the samples contained standard medium DMEM with 10% foetal bovine serum and gentamicin (40 jg/ml) mentioned above, and the second half contained osteogenic medium, i.e. the standard medium further supplemented with ß-glycerophosphate, L-glutamin, ascorbic acid, dihydroxyvitamin D3, dexamethason, 10% foetal bovine serum and gentamicin (40 jg/ml). Using an Enzyme-Linked ImmunoSorbent Assay (ELISA), we measured the concentration of the Inter¬cellular Adhesion Molecule-1 (ICAM-1, a marker of cell immune activation) and osteocalcin (a marker of osteogenic cell differentiation). These measurements were performed in homogenates of cells on days 4 and 7 after seeding, and the concentration of both markers was measured per cell or per mg of protein. On day 7, the amount of osteocalcin was measured and compared in cells cultured in the standard and osteogenic media. We also measured TNF-а and IL- 1ß, i.e. other markers of cell immune activation. These cytokines are important mediators of the inflammatory response, and they are involved in a variety of cellular activities, including cell proliferation and differentiation. We measured the secretion of these markers into the cell culture medium in murine macrophage-like RAW264.7 cells (American Type Culture Collection, Manassas, VA). The samples (9x9 mm) were inserted into polystyrene 24-well cell culture plates (TPP, Tra- sadingen, Switzerland; well diameter 1.5 cm). Each well contained 30,000 (approx. 16 980 cells/cm2) cells and 1.5 ml of the culture medium. RAW 264.7 cells were cultured in the RPMI-1640 medium (Sigma; 10% fetal bovine serum, 40 jg/mL gentamicin). After 7 days of cultivation, the cell culture medium was collected and used for measuring the concentration of TNF-а and IL-1ß by a sandwich ELISA using commercially available kits. A mouse TNF-а kit and an IL- 1ß Quantikine ELISA kit were used for the RAW 264.7 cells. Both kits were purchased from R and D Systems (Minneapolis, MN) and used according to the manufacturer's protocol. The results indicated that the number of initially adhering MG 63 cells on day 1 after seeding was significantly lower on the titanium (5320±390 cells/cm2) and on the stainless steel (4110±370 cells/cm2) than on the control polystyrene culture dishes (7740±350 cells/cm2). However, on day 4 after seeding, the cell population density on both metallic materials became significantly higher than on the control polystyrene dishes (75200±2890 cells/cm2 on Ti and 90 870±2350 cells/cm2 on steel vs. 56440±1180 cells/cm2 on polystyrene). This suggests faster cell proliferation on both metallic materials than on polystyrene. At the same time, the cell number on the stainless steel samples was significantly higher than on the Ti samples. On day 7, the differences in the number of adhered cells on the two metals and on the control polystyrene substrate was on an average similar (from 328780±680 cells/cm2 to 362200±760 cells/cm2). The cell viability on all tested materials was almost 100% in all culture intervals. The morphology of the cells adhered on the studied materials was similar to the morphology of the cells on the control polystyrene dishes, i.e. the cells were mostly flat and polygonal, and the size of their cell spreading areas was similar on all tested materials. The cells were distributed homogeneously on the entire material surface, and on day 4 they started to form confluent cell layers. On day 4, we measured the amount of ICAM-1 by the ELISA test. This immunoglobulin molecule is typically expressed on cells of the immune system, but it is also expressed on other cell types, including MG 63, during their immune activation, e.g. by an artificial growth support. In this case, ICAM-1 molecules on cells are bound byß2-integrin receptors on inflammatory cells (for a review, see [4]). Surprisingly, titanium seemed to be more immunogenic than stainless steel, which was indicated by a higher concentration of ICAM-1 per cell and mg of protein in cells on day 4 after seeding. However, on day 7, there was no difference between the concentrations of ICAM-1 per cell and mg of protein in cells on titanium and on stainless steel. The second molecule that we measured was osteocalcin, a calcium-binding extracellular matrix glycoprotein, an important marker of the bone formation process. The concentration of osteocalcin on day 4 in the standard culture medium was higher in MG 63 cells on the titanium and stainless steel than on the control polystyrene samples. This could be explained by the fact that the metals are harder than polystyrene. It is known that harder substrates promote osteogenic cell differentiation, while softer substrates direct the cell differentiation towards neural or muscle phenotype [5]. In addition, the osteogenic differentiation was further supported by the osteogenic medium, as indicated by a higher concentration of osteocalcin in cells grown in this medium compared to cells in the standard medium on day 7 after seeding. On day 7 after seeding murine macrophage-like RAW264.7 cells on the tested materials, the concentration of TNF-а in the culture medium ranged on an average from 57.10 to 79.39 pg per 2000000 cells. The concentration of TNF-а in the medium from Ti and Fe was significantly higher than in the medium from the control polystyrene dishes. The highest value (79.39 pg/2000000 cells) was found in the medium taken from RAW264.7 cells on Ti. The second molecule that we tested was IL-1ß. No significant differences in the concentration of IL-1ß were detected in the culture medium obtained from RAW264.7 cells on all tested materials. In other words, neither type of metallic material, i.e. Ti and Fe, evoked significantly higher production of IL-1ß by RAW 264.7 cells than standard polystyrene cell culture dishes. It can be concluded that the tests of biocompatibility and immune activation confirmed that titanium and stainless are promising for construction of bone implants and for good integration with the surrounding bone tissue.

12

Modeling of heat transfer in the cooling wheel in the melt-spinning process

Karpe B., Kosec B., Bizjak M.

Journal of Achievements in Materials and Manufacturing Engineering

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2011

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Vol. 46, nr 1

88--94

EN

Purpose: In the case of continuous casting of metal ribbons with the melt-spinning process on the industrial scale, larger quantity of melt could lead to a slow excessive warming of the chilling wheel, which would further lead to solidification of a ribbon at non-uniform conditions and increased wearing of the wheel. Primary goal of our work was to determine to what extent the release of heat during contact of the melt/ribbon on the circumferential surface of the chilling wheel affect its surface temperature rise, and inversely how much elevated temperature of the chill wheel surface affects on metal ribbon cooling rate and its solidification velocity. Design/methodology/approach: On the basis of developed mathematical model, a computer program was made and used for analyses of heat transfer in the melt-spinning process. Findings: The calculations show that contact resistance between metal melt and chilling wheel has a great influence on melt/ribbon cooling and chill wheel heating rate, and must not be neglected in numerical calculations, even if its value is very low. In the case of continuous casting, significant “long term” surface temperature increase may take place, if the wheel is not internally cooled. But inner cooling is effective only if wheel casing thickness is properly chosen. Research limitations/implications: Influence of process parameters and chill wheel cooling mode on cooling and solidifying rate over ribbon thickness are outlined. Practical implications: Directions for the chill wheel cooling system design are indicated. Originality/value: New method for determining contact resistance through variable heat transfer coefficient is introduced which takes into account physical properties of the casting material, process parameters and contact time/length between metal melt/ribbon and substrate and enables cooling rate prediction before the experiment execution. In the case of continuous casting, heat balance of the melt-spinning process is calculated and influence of the chill wheel cooling mode on cooling rate of metallic ribbon is analyzed.

13

Dilatometric investigations of phase transformations at heating and cooling of hardened, unalloyed, high-carbon steels

Pacyna J.

Journal of Achievements in Materials and Manufacturing Engineering

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2011

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Vol. 46, nr 1

7--17

EN

Purpose: The reason for writing this paper was to describe the kinetics of phase transformations during continuous heating from hardened state and subsequent cooling of unalloyed high carbon steel. Design/methodology/approach: Dilatometric investigations were performed using a DT 1000 dilatometer of a French company Adamel. Samples after quenching and quenching and sub-quenching in liquid nitrogen (-196 °C) were heated up 700 °C at the rate of 0.05 °C/s and subsequent cooled to room temperature at the rate of 0.05 °C/s. Findings: Regardless of heating the hardened high-carbon steel to 700 °C, a small fraction of the retained austenite remained in its structure, and was changing into fresh martensite only during cooling in the temperature range: 280°C-170°C. Research limitations/implications: Schematic presentation of the differential curve of tempering of the hardened high-carbon, unalloyed steel illustrating the phase transformations occurring during heating from hardened state. Practical implications: An observation, that a small fraction of the retained austenite remained in the structure of tempered high-carbon steel, indicates that even unalloyed steel should be tempered two times. Originality/value: Detailed descriptions of kinetics phase transformations during heating from hardened state of unalloyed high carbon steel.

14

Wpływ wartości statycznych naprężeń na obliczeniową trwałość zmęczeniową wybranych materiałów metalowych

Kluger K., Łagoda T.

Przegląd Mechaniczny

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2010

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nr 5

13-17

PL

W pracy przedstawiono rezultaty badań zmęczeniowych próbek ze stopu aluminium 2017-T4(A) oraz stali stopowych S355J2WP i S355J0 w warunkach stałoamplitudowych proporcjonalnych kombinacji zginania ze skręcaniem z uwzględnieniem wartości średniej naprężenia. Wyniki badań eksperymentalnych porównano z wynikami obliczeń z wykorzystaniem modeli Goodmana, Gerbera i Morrowa oraz modelu energetycznego. W przypadku metod obliczeń opartych na naprężeniach, wieloosiowy stan naprężenia redukowano do jednoosiowego, wykorzystując zależność Hubera-Misesa. W przypadku metody energetycznej, wieloosiowy stan naprężenia redukowano do jednoosiowego, stosując parametr naprężeniowo-odkształceniowy w płaszczyźnie krytycznej.

EN

The paper contains the results of fatigue tests of specimens made of the aluminium alloy 2017-T4(A) and S355J2WP and S355JO alloy steels under constant amplitudę proportional combined bending with torsion including stress mean values. Results of tests were compared with the calculated data using the models by Goodman, Gerber and Morrow, and the stress-strain parameter (Was). In the case of calculations based on stresses, the multiaxial stress state was reduced to the uniaxial one, using the Huber-Mises relationship. In the case of energy method, the multiaxial stress state was reduced to the uniaxial one with the stress-strain parameter on the critical piane.

15

Damage of brittle materials at super-deep penetration

Owsik J., Jach K., Noga J., Usherenko S., Malamud V., Usherenko Y.

Journal of Technical Physics

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2009

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Vol. 50, no 4

343-352

EN

Interaction of glass arid silicon monocrystals with clusters of dust particles is described in the paper. Protective metallic shells become a source of new damage factors in conditions of super-deep penetration (SDP). Penetration of micro-jets into a glass sample volume occurs as precession with respect to the axis of a jet motion in a barrier. The form of bands of superficial damages corresponds to sawtooth change of parameters of electromagnetic field which controls motion of a dense plasma micro-jet. The energy anomaly factor of the order of Eg/ESi ≈ 8.4 was found from comparison of the damages in glass and silicon.

16

FEM analysis of drills used in bone surgery

Paszenda Z., Basiaga M.

Archives of Materials Science and Engineering

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2009

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Vol. 36, nr 2

103-109

EN

Purpose: The aim of the work was determination of biomechanical analysis of a surgical drill – bone system in simulated conditions of drilling in a bone. Design/methodology/approach: Geometrical model of the selected surgical drill and simulated femur (cortical bone) was worked out in the Inventor Professional 2008. The value geometry of the edge was point angle (2κ1 = 90° and 2κ2 = 120°). Numerical model was prepared in ANSYS Workbench v. 11. Meshing was realized with the use of SOLID 187 elements. Evaluate boundary conditions to numerical analysis imitate phenomena in real system with appropriate accuracy. Drill was loaded with forces in the range F= 100-200 N and torque T = 0.04 Nm. Calculations were carried out for two kinds of metallic material of the drill. Findings: The effect of numerical analysis was determination of strains and stresses in working part of the drill. Results of analysis indicate diverse values of strains and stresses distribution in working part of the drill depending on its geometry. The maximum values of strains and stresses were obtained for the drill of point angle 2κ1=120°. Research limitations/implications: In order to simulate phenomena in real system, a simplified model of surgical drill – femur system was worked out. The simplifications concerned mostly geometry of a femur. The femur was represented by disc of height h = 10 mm, corresponding with thickness of cortical bone. Originality/value: The numerical analysis of the surgical drill – femur system in simulated conditions of drilling in a bone can be a basis for optimization of cutting edge geometry of surgical tools as well as for selection of their mechanical properties.

17

Biomechanical analysis of plate stabilization on cervical part of spine

Kiel M., Marciniak J., Szewczenko J., Basiaga M., Wolański W.

Archives of Materials Science and Engineering

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2009

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Vol. 38, nr 1

41-47

EN

Purpose: The main aim of the work was determination of biomechanical analysis of cervical spine – stabilizer system made of stainless steel (Cr-Ni-Mo) and Ti-6Al-4V alloy. Design/methodology/approach: To define biomechanical characteristic of the system the finite elements method (FEM) was applied. Geometric model of part of spine C5-C7 and stabilizer were discretized by SOLID95 element. Appropriate boundary conditions imitating phenomena in real system with appropriate accuracy were established. Findings: The result of biomechanical analysis was calculation of displacements and stresses in the vertebras and the stabilizer in a function of the applied loading: 50-300 N for the stabilizer made of stainless steel (Cr-Ni-Mo) and Ti-6Al-4V alloy. Research limitations/implications: The result of biomechanical analysis for plate stabilizer obtained by FEM can be use to determine a construction features of the stabilizer, and to select mechanical properties of metallic biomaterial and estimation of stabilization quality. The calculation of displacements for part C5-C7 show that the proposed type of stabilizer enables correct stabilization used to clinical apply. Practical implications: The results of biomechanical analysis showed correct mechanical properties used to made the plate stabilizer. Originality/value: The obtained numerical results should be verified in “in vitro” tests.

18

Morphology prediction of intermetallics formed in 4xxx type of aluminium alloy

Mrówka-Nowotnik G., Sieniawski J., Wierzbińska M.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 31, nr 2

262-268

EN

Purpose: It is intention of this paper to present results of studies of AlSi5Cu2Mg cast alloy in T6 condition with emphasis on composition of intermetallic phases. It was revealed that the microstructure of the alloy is characterized by three different intermatallic phases. Their morphology depends on the base metal and crystallization parameters applied. Design/methodology/approach: Microstructural examination was conducted for the specimens using optical metallography, scanning (SEM) and transmission (TEM) electron microscopy as a complement to light optical investigation. Differential scanning calorymetry was utilized to assist in intermetallics identification. Phase identification was done by electron diffraction spectrometry microanalyser EDS using X-ray mapping technique on representative area for the structure of the material and a quantitative analysis was conducted for the large particles, which are large enough in size for individual analysis. Findings: Three types of intermetallic α -AlFeMnSi phase precipitates vary on shapes and chemical compositions were determined. Their morphology was mainly influenced by the parameters of crystallization process. The intermetallics can precipitate in form of needle or ''Chinese script''. The shape of phases determined can also be modified by adjusted modifying heat treatment process of the alloy. Research limitations/implications: It is recommended to perform further analysis of the alloy by using more sophisticated technique for microsctructure observation - TEM in order to clarify a formation model and provide characteristic of the refined phases. These dispersed, smaller in size intermetallics compared to these characterized in this paper, have a considerable impact on the mechanical properties of the alloy. Practical implications: It is important to develop a. predictive understanding of intermetallics formation through crystallization and heat treatment process since they play the most significant role in development of final properties of a material designed for utilitarian application. Originality/value: This work is a contribution to the understanding of precipitation hardening behavior of the intermetallic phases and clarifying their formation mechanism by determination of their chemistry and occurring sequence in the microstructure during crystallization and heat treatment processes.

19

Corrosion behaviour of metallic biomaterials used as orthodontic wires

Ziębowicz A., Walke W., Barucha-Kępka A., Kiel M.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 27, nr 2

151-154

EN

Purpose: The aim of the work was evaluation of the corrosion resistance of the commercial metallic orthodontic wires from different manufacturers in simulated intra-oral environment. Design/methodology/approach: Corrosion resistance tests were carried out in artificial saliva at the temperature 37 ± 1° C with the use of the VoltaLab ® PGP 201 system for electrochemical tests. The saturated calomel electrode (SCE) was applied as the reference electrode and the auxiliary electrode was a platinum foil. The evaluation of pitting corrosion was realized by recording of anodic polarization curves with the use of the potentiodynamic method. In order to evaluate crevice corrosion resistance the samples were polarized in the potential equal to 0.8 V by 900 seconds. Findings: Results of corrosion resistance tests of the CrNi, NiTi and CuNiTi wires showed comparable data of parameters obtained in the artificial saliva. Research limitations/implications: The obtained results show the influence of artificial saliva on the electrochemical corrosion of orthodontic wires. In order to demonstrate the higher risk of corrosion, which can have two consequences: a loss of the physical properties and the release of Ni ions (which have been shown to be toxic and the cause of allergic reactions) - additional research on fatigue corrosion should be carried out. Originality/value: The analysis of the obtained results show that that commonly used materials for making orthodontic wires (because of their interesting properties - elasticity and shape memory) can be used in different orthodontic treatment stages to correct numerous clinical conditions. The most favorable characteristics were observed for the new NiTi samples (American Orthodontics).

20

Biaxial extension of a plane single crystal

Merabet K., Chenaoui A., Sidoroff F., Darrieulat M.

Archives of Mechanics

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2008

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Vol. 60, nr 5

363-384

EN

This paper concerns the rigid-plastic modelisation of a f.c.c. single crystal, deforming by crystallographic slip, under large strain. Adopting the plane single crystal model, which corresponds to a true two-dimensional evolution of a real three-dimensional crystal, the activity of slip systems and the plastic indetermination, due to multiplicity of solutions, are studied according to the rate-independent Schmid law or the rate-dependent Bingham law. To promote a more general situation of potential multiple slip and therefore of potential indeterminacy, the biaxial loading is investigated. Based on this model and the Bingham slip law, the indeterminacy problem is surmounted, by adopting the geometrical analysis in the strain rate space and it is proved that the linear viscoplastic analysis is a new way of solving the indeterminacy problem.