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1
Content available Rekonstrukcja tkanki chrzęstnej biomateriałami polimerowymi – wyniki makroskopowe i histologiczne po 26 i 52 – tygodniowym okresie obserwacji
Ścierski W., Polok A., Namysłowski G., Nożyński J., Turecka L., Urbaniec N., Pamuła E.
Engineering of Biomaterials
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2009
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Vol. 12, no. 89-91
47--49
2
Content available remote Structure and properties of laser alloyed gradient surface layers of the hot-work tool steels
Dobrzański L., Bonek M., Hajduczek E., Labisz K., Piec M., Jonda E., Polok A.
Journal of Achievements in Materials and Manufacturing Engineering
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2008
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Vol. 31, nr 2
148-169
EN
Purpose: The purpose of this research paper is focused on the 55NiCrMoV7, 32CrMoV12-28, X40CrMoV5-1, X38CrMoV5-3 hot work tool steels surface layers improvement properties using HPDL laser. The paper present laser surface technologies, investigation of structure and properties of the hot work tool steels alloying with ceramic particles using high power diode laser HPDL. Design/methodology/approach: Investigation indicate the influence of the alloying carbides on the structure and properties of the surface layer of investigated steel depending on the kind of alloying carbides and power implemented laser (HPDL). Laser alloying of surface layer of investigated steel without introducing alloying additions into liquid molten metal pool, in the whole range of used laser power, causes size reduction of dendritic microstructure with the direction of crystallization consistent with the direction of heat carrying away from the zone of impact of laser beam. Findings: In the effect of laser alloying with powders of carbides NbC, TaC, TiC, WC and VC occurs size reduction of microstructure as well as dispersion hardening through fused in but partially dissolved carbides and consolidation through enrichment of surface layer in alloying additions coming from dissolving carbides. Introduced particles of carbides and in part remain undissolved, creating conglomerates being a result of fusion of undissolved powder grains into molten metal base. In effect of convection movements of material in the liquid state, conglomerates of carbides arrange themselves in the characteristic of swirl. Remelting of the steel without introducing into liquid molten pool the alloying additions in the form of carbide powders, causes slight increase of properties of surface layer of investigated steel in comparison to its analogical properties obtained through conventional heat treatment, depending on the laser beam power implemented for remelting. Practical implications: It has the important cognitive significance and gives grounds to the practical employment of these technologies for forming the surfaces of new tools and regeneration of the used ones. The increase of hardness of surface layer obtained throughout remelting and alloying with carbides by high power diode laser is accompanied by increase of tribological properties, when comparing to the steel processed with conventional heat treatment. Originality/value: The outcome of the research is an investigation and proving the structural mechanisms accompanying laser remelting and alloying. The artificial neural networks were used to determine the effect of the technological effect of laser alloying on hardness and resistance wear abrasion of the hot work tool steels.
3
Content available remote Comparison of the thermal fatigue surface layers of the X40CrMoV5-1 hot work tool steels laser alloyed
Dobrzański L. A., Jonda E., Polok A., Klimpel A.
Journal of Achievements in Materials and Manufacturing Engineering
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2007
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Vol. 24, nr 2
135-138
EN
Purpose: The comparison of thermal fatigue and mechanical properties of the hot work tool steels alloyed with carbide powders has been presented. The effect of laser alloying with powders on the surface layers alloying with HPDL was evaluated. Design/methodology/approach: In this paper the result of laser surface alloying is discussed. The material used for investigation were hot work tool steels X40CrMoV5-1 and 55NiCrMoV7 alloyed with TiC or TaC using high power diode laser. Findings: The thermal fatigue resistance measured with the average cracks deep subjected to steel alloyed with TiC powder is few times smaller compared to the steel after a conventional heat treatment, which was used as a reference material. The hardness value increases according to the laser power used in alloying. Research limitations/implications: It is necessary to continue the research to determine alloying parameters for demanded properties of hot work tool steels surface layers. Practical implications: The proposed new methods of enhancement fatigue resistant of hot work tool steels was the aim goal of this work. Originality/value: Laser alloying by using different carbide powders and HPDL laser is a new way to improve the structure and mechanical properties of the hot work tool steels.
4
Content available Degradable scaffold materials for cartilage regeneration
Pamuła E., Polok A., Menaszek E.
Engineering of Biomaterials
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2007
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Vol. 10, no. 69-72
3-5
EN
Two scaffolding materials for cartilage regeneration were produced from poly(L-lactide-co-glycolide) (PLG) and PLG modified with sodium hyaluronate (PLG-Hyal). The scaffolds were characterized in terms of their microstructure and surface chemistry. Biological properties of the scaffolds were also evaluated by implantation of the scaffolds into auricular cartilage of the rabbits for 1 and 4 weeks. Histological and histochemical examinations show that both scaffolds promote regeneration of the cartilage, although the quickest regeneration was found after implementation of PLG-Hyal.
5
Content available remote Structure and properties of surface layers obtained by alloying of the hot work tool steels
Dobrzański L. A., Polok A., Jonda E.
Journal of Achievements in Materials and Manufacturing Engineering
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2006
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Vol. 17, nr 1-2
329--332
EN
Purpose: The aim of the present work was to study the microstructure and properties produced after laser alloying of the 55NiCrMoV7 and X40CrMoV5-1 an alloy hot-work tool steels. Design/methodology/approach: Structure investigation was performed using the light microscope Leica MEF4A supplied by Zeiss. Phase composition and crystallographic structure were determined by the X-ray diffraction method using the DRON 2.0. The measurements of microhardness have been performed using Shimadzu microhardness intender equipped with electronic sensor that allows the direct readout of the hardness values. Findings: The metallographic investigations on light microscope show that steel after laser remelting can be characterized by a dendrite structure. Metallographic examinations on the scanning microscope with the EDX attachment confirm the occurrence of the niobium carbides in the surface layer of the investigated steels. Research limitations/implications: In order to evaluate with more detail the possibility of applying these surface layers in tools, further investigations should be concentrated on the determination of the thermal fatigue resistance of the layers. Practical implications: The surface layer of the hot work steel alloyed with ceramic powder have good properties and make possibility for uses it in various technical and industrial applications. Originality/value: The microstructure and properties of the surface layer of the 55NiCrMoV7 and X40CrMoV5-1 hot-work tool steels alloying with ceramic powder were compared.
6
Content available remote Comparison of the abrasion wear resistance of the X40CrMoV5-1 and 55NiCrMoV7 hot work tool steels with their surface layer enriched with the ceramic powders
Dobrzański L. A., Jonda E., Polok A.
Journal of Achievements in Materials and Manufacturing Engineering
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2006
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Vol. 15, nr 1-2
32--38
EN
Purpose: In the paper there are presented the results of the influence of laser remelting parameters on the properties of the surface layer of the X40CrMoV5-1 and 55NiCrMoV7 hot work steel, using the high power diode laser (HPDL). The aim of this work was to compare the abrasion wear resistance of the X40CrMoV5-1 and 55NiCrMoV7 hot work tool steel surface layers enriched with the TiC, WC and VC ceramic powders. The surface layers of hot work tool steel remelted with a diode laser beam have been metallographically examined and analyzed with the use of a hardness testing machine. Design/methodology/approach: The high power diode laser (HPDL) and ceramic powders WC, VC and TiC were used. Remelting and alloying processes were carried out at the constant remelting rate and focus shape, varying the laser beam power for the alloyed test pieces in the range from 1,2 – 2,3 kW. Findings: On the basis of the wear abrasion tests carried out on 55NiCrMoV7 and X40CrMoV5-1 steels it could be ascertained that each of those steels is characterized by different resistance for the same powders and the power of the laser beam. In the case of employing 1,2 kW laser, the surface layer formed using the majority of the investigated portions undergoes a total wear during the wear-rate test which also causes the wear of the initial material. When 2,3 kW is employed, the surface layers have crack and microcrack defections which decrease the resistance to the abrasion. The smallest mass loss for 55NiCrMoV7 steel among all the analyzed cases has been observed for the surface layers alloyed with TiC powder, at the of the laser beam power of 2,3 kW and for WC powder at 1,2 kW laser beam power. For the X40CrMoV5-1 steel the smallest mass decrement has been observed forthe steel alloyed with WC powder at 1,2 kW laser beam power and VC powder at 1,6 kW laser beam power. Practical implications:The investigations showed that as a result of the applied laser processing there is the increase in the hardness and resistance to abrasion of the surface layers in relation to the output material. Originality/value: Wear resistance and hardness of two hot work tool steels were compared.
7
Porównanie struktury i własności stali narzędziowych stopowych do pracy na gorąco modyfikowanych laserowo
Dobrzański L. A., Jonda E., Polok A.
Inżynieria Materiałowa
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2006
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Vol. 27, nr 3
131-134
PL
Stalom narzędziowym stopowym do pracy na gorąco, należącym do grupy stali o ugruntowanej pozycji wśród materiałów narzędziowych, stawia się coraz wyższe wymagania, dotyczące niezawodności i trwałości eksploatacyjnej. Jednym z licznych sposobów modyfikowania własności użytkowych tych stali jest obróbka laserowa, która należy obecnie do najnowocześniejszych metod, znajdujących coraz większe zastosowanie w wielu ośrodkach przemysłowych na świecie. W pracy zbadano strukturę i własności stali stopowych narzędziowych do pracy na gorąco stopowanych proszkami ceramicznymi przy użyciu lasera diodowego dużej mocy HPDL. Celem pracy było określenie wpływu podstawowych parametrów stopowania na własności i strukturę warstw wierzchnich stali, a także zależność głębokości warstwy przetopionej od zastosowanej do przetopienia mocy lasera. Do badań wykorzystano próbki otrzymane ze stali X40CrMoV5-1 oraz 55NiCrMoV7 poddane konwencjonalnej obróbce cieplnej, a następnie przetapiane i stopowane proszkiem ceramicznym węglika tantalu TaC, laserem diodowym w zakresie mocy 1,2-2,3 KW. Przeprowadzono standardowe badania metalograficzne z wykorzystaniem mikroskopii świetlnej i elektronowej oraz badania chropowatości. Wykonano również badania rentgenograficzne w celu identyfikacji faz występujących w otrzymanych warstwach wierzchnich.
EN
The properties of hot work tool steels, important group of steels among tool materials, have to be modified in order to improve their reliability and exploitative stability. Laser processing is one of the most up-to-date techniques that allow modification of usable properties of those steels. The role and application of laser processing in number of worldwide industrial centers is permanently growing. This paper focuses on the microstructure and properties of hot work tool steels alloyed with ceramic powders using high power diode laser (HPDL). The main goal of the research was to analyze the influence of main alloying parameters on properties and microstructure of steels’ surface layers, as well as dependence of depth of alloyed surface layer on applied laser power. The samples used for investigation were obtained from X40CrMoV5-1 and 55NiCrMoV7 steels, conventionally heat treated, remelted and alloyed with tantalum carbide ceramic powder using diode laser in the power range of 1,2-2,3 KW. Samples were studied by scanning electron and light optical microscopy. X-Ray analysis was carried out for obtained surface layers phases identification. Additionally the roughness of investigated steels was measured.
8
Content available Rekonstrukcja ubytków przegrody nosa materiałami syntetycznymi - doniesienie wstępne
Polok A., Ścierski W., Błażewicz M., Namysłowski G.
Inżynieria Biomateriałów
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2006
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R. 9, nr 58-60
44-45
9
Pomiar potencjału Redox w procesie denitryfikacji w oczyszczalnin ścieków
Polok A.
Forum Eksploatatora
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2003
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Nr 1 (10)
12-15
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