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1

Bond strength of orthodontic adhesives to dry and saliva-moistened enamel a comparative in vitro study

Stefański T., Kloc-Ptaszna A., Postek-Stefańska L.

Archives of Materials Science and Engineering

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2019

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Vol. 96, nr 2

79--84

EN

Purpose: To compare the bond strengths of six different dental adhesives to dry and salivamoistened enamel. Design/methodology/approach: One hundred twenty stainless steel brackets were bonded to human mandibular third molars with six materials: Enlight LC® (Ormco Corp), Grengloo® (Ormco Corp), Light Bond® (Reliance Orthodontic Products), Charisma® (Heraeus Kulzer), SmartBond® (Gestenco), and Transbond XT® with MIP® primer (3M Unitek). One half of the specimens in each group (n=10) was bonded to dry enamel, while the other half to saliva-moistened enamel. Bond strength testing was performed with a wire loop loading technique after 30-min incubation in artificial saliva. Failure mode was evaluated using adhesive remaining index (ARI). Findings: No significant differences in bond strength to dry enamel were noted for all composite materials (p>0.05). SmartBond exhibited significantly greater bond strength to moistened enamel (7.10 ± 1.47 MPa) and comparable with other composite materials to dry enamel. Composite materials demonstrated significantly reduced bond strength to saliva-moistened enamel (p<0.001), except for Transbond MIP, whose bond strength was not significantly decreased by saliva contamination (p=0.089). There was not statistically significant difference between bond strength of SmartBond and Transbond to saliva contaminated enamel. A higher incidence of cohesive failures was noted for all materials. Research limitations/implications: Composite light-cured materials provide adequate bond strength to dry enamel. Cyanoacrylate adhesive provides sufficient bond strength only under moist conditions. Transbond XT+MIP has sufficient bond strength to either dry or saliva-moistened enamel. Practical implications: The study evaluated the bonding strength of orthodontic brackets, which is a critical parameter in orthodontics, especially in situations that do not allow for proper isolation from saliva, such as bonding to impacted teeth following surgical exposure. Originality/value: Bond strengths evaluated with loop loading technique in different study environments would help the orthodontist to choose the most effective adhesive for the specific clinical situation.

2

Preparatyka do celów mikroskopii świetlnej i skaningowej

Kloc-Ptaszna A., Pakieła W., Snopiński P.

LAB Laboratoria, Aparatura, Badania

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2017

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R. 22, nr 6

24--28

3

Erosive potential of calcium-supplemented citric acid on bovine enamel

Stefański T., Malara P., Kloc-Ptaszna A., Postek-Stefańska L., Tyrpień-Golder K, Dobrzański L. A.

Archives of Materials Science and Engineering

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2013

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Vol. 64, nr 2

175--181

EN

Purpose: of this paper is to present results of wear resistance investigations of epoxy-hard coal composites produced by gravity casting Design/methodology/approach: In short introduction wear resistance of polymers is presented, methods used to prepare composites together with short characterization of physical properties of applied fillers are described. Wear resistance of the specimens was determined using Schopper-Schlobach method and APGi device. During the test, the rigidly fixed specimen moves with constant velocity along a rotating cylinder with abrasive paper type corundum P60 on its surface. Wear resistance of specimens was determined after 20 meters distance of abrasion under pressing load of10Nand expressed as the weight loss of the specimen after abrasion. Findings: Addition of the hard coal particles into the epoxy resin matrix caused a decrease of the wear resistance. Wear resistance decreased in a little extend with increasing filler content. Statistical analysis of achieved results showed that the influence of hard coal on wear resistance is significant comparing neat resin and filled resin but is not significant comparing composites with different solid particles content. Practical implications: Tested composite materials can be applied among others in electrical or chemical industry where electrical properties are important but wear resistance is not so important. Originality/value: New types of epoxy-hard coal graded composites were tested. It was demonstrated that by proper gravity casting technology control it is possible to produce graded composites for which hard coal particles do not deteriorate the wear resistance in significant extend.

4

Effect of water dilution and alcohol mixing on erosive potential of orange juice on bovine enamel

Malara L., Kloc-Ptaszna A., Dobrzański L., Górniak M., Stefański T.

Archives of Materials Science and Engineering

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2013

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Vol. 62, nr 1

15--21

EN

Purpose: This in vitro study aimed to evaluate the changes of erosive potential of an orange juice before and after mixing with water and alcohol. Design/methodology/approach: Fifty enamel specimens obtained from bovine teeth were prepared and randomly assigned into the following groups (n=10) with different erosive solution: I. commercially available pure orange juice (Cappy, Coca Cola Co.), II. orange juice diluted with distilled water at a ratio 3:1 (v/v), III. orange juice mixed with vodka (Smirnoff, 40% ethanol, Polmos) at a ratio 3:1 (v/v); IV. Orange juice diluted with distilled water (1:1, v/v), V. Orange juice mixed with vodka (1:1 v/v). The enamel specimens were submitted to a short-term erosion-remineralization cycling model (five 1-min erosion challenges in-between six 10-min remineralization periods in artificial saliva). Erosive potential of the drinks was assessed on the basis of chemical analysis and percent surface microhardness change (%SMHC) calculated from Vickers surface microhardness measurements before and after cycling. In chemical analysis of the experimental drinks, the pH value, titratable acidity, and buffer capacity (β) were determined. Findings: The pH of tested drink remained low even after dilution with water or mixing with alcohol, however, titratable acidity decreased after addition of water and alcohol. Short-term erosion-remineralization cycling resulted in significantly decreased surface microhardness of enamel specimens in all experimental groups. In the proportion of 3:1, juice mixed with alcohol resulted in significantly smaller %SMHC than juice diluted with water. This difference was not observed at a ratio 1:1. Practical implications: Consumers should be aware of tooth damage by drinks with low pH and high titratable acidity, even when mixing them with water and alcohol. Originality/value: To the best of our knowledge, this is the first study comparing the erosive effect of water-diluted orange juice with that of juice mixed with alcohol.

5

Fabrication methods and heat treatment conditions effect on structure and properties of the gradient tool materials

Dobrzański L., Kloc-Ptaszna A., Pawlyta M., Pakieła W.

Archives of Materials Science and Engineering

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2012

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Vol. 56, nr 1

5-21

EN

Purpose: This work concerns manufacturing and research on a new group of the gradient tool materials, manufactured by the conventional powder metallurgy method, consisting in compacting a powder in a closed die and sintering it. Design/methodology/approach: The materials were obtained by mixing the powders of the HS6-5-2 high-speed steel, tungsten carbide (WC). The mixes were poured one after another into the die, yielding layers with the gradually changing volume ratio of carbides within the high-speed steel matrix. Structural research by using the scanning and transmission electron microscopes, x-ray microanalysis and density, hardness and porosity tests, were performed. Structure and hardness of selected materials after heat treatment were also investigated. The pin on plate test was used in order to examine the tribological properties of the analyzed materials. Findings: On the basis of the results of the research, it was found that it is possible to obtain gradient materials by the powder metallurgy methods, in order to ensure the required properties and structure of the designed material. It was shown that the new sintered graded materials are characterized by a multiphase structure, consisting of ferrite, primary carbides of the high speed steel, of the MC and M6C type, and dependently of the reinforcement phase, of the tungsten carbide WC which are introduced into the material, in the powder form. It has been proved by the pin on plate test that the addition of the tungsten carbide to the high-speed steel significantly improved the tribological properties. Practical implications: Developed material is tested for turning tools. Originality/value: The material presented in this paper has layers consisting of the carbide-steel with growing hardness on one side, and on the other side the high-speed steel, characterized by a high ductility.

6

Manufacturing technologies of sintered graded tool materials evaluated according to foresight methodology

Dobrzańska-Danikiewicz A., Kloc-Ptaszna A., Dołżańska B.

Archives of Materials Science and Engineering

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2011

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Vol. 50, nr 2

69-97

EN

Purpose: The goal of this paper is to evaluate the development efficiency of conventional technologies of powder metallurgy used for graded tool materials manufacturing. The technologies were divided into three groups according to the matrix type and the percent fraction volume of components in the powders layers. Design/methodology/approach: In the framework of foresight-materials science research a foresight matrices set was created, materials science experiments using light, transmission and scanning electron microscopes, X-ray diffractometer, microhardness tester, work-stands for testing of fatigue resistance, mechanical fatigue strength, fracture toughness were conducted and technology roadmaps were prepared. Findings: Quite high potential and attractiveness of the analysed technologies against the environment, as well as good development perspectives in industry were shown. Research limitations/implications: Research concerning graded tool materials constitute a part of a larger research project aimed at identifying, researching, and characterising the priority innovative technologies in the field of materials surface engineering. Practical implications: The presented materials science results prove a manufacturing possibility of elements with ductile cores and hard coatings using conventional technologies of powder metallurgy. These technologies are recommended for practical implementation in industry, especially for cutting tools. Originality/value: The originality of this paper the value evaluation of manufacturing technologies of graded tool materials against background environment including the influence of the chemical composition and sintering conditions on the surface layers hardness.

7

Structure and properties of the gradient tool materials based on a high-speed steel HS6-5-2 reinforced with WC or VC carbides

Dobrzański L. A., Kloc-Ptaszna A.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 37, nr 2

213-237

EN

Purpose: This paper concerns manufacturing and researching a new group of the gradient tool materials, manufactured by a conventional powder metallurgy method, consisting in compacting a powder in a closed die and sintering it. Design/methodology/approach: The materials were obtained by mixing the powders of the HS6-5-2 high-speed steel, tungsten carbide (WC), and vanadium carbide (VC). The mixes were poured one by one into the die, yielding layers with the gradually changing volume ratio of carbides within the high-speed steel matrix. Structural research by using the scanning and transmission electron microscopes, x-ray microanalysis and density, hardness and porosity tests, were performed. Structure and hardness of selected materials after heat treatment were also investigated. Findings: On the basis of the results of the research, it was found that it was possible to obtain gradient materials by the powder metallurgy methods, in order to ensure the required properties and structure of the designed material. It was shown that the new sintered graded materials were characterized by a multiphase structure, consisting of ferrite, primary carbides of the high speed steel, of the MC and M6C type, and dependently of the reinforcement phase, of the tungsten carbide WC or the vanadium carbide VC, which were introduced into the material, in the form of powder. Additionally in the structure of the WC-reinforced materials the W2C phase occurs. The gradient tool materials reinforced with the WC carbide were characterized by a higher hardness, and a lower porosity in relation to the materials reinforced with the VC carbide. It was found that the desired structure and properties (density, porosity and hardness) had the material containing 25% of the WC carbide in the surface layer, after sintering at the temperature 1210oC, for 30 minutes. The heat treatment application causes a significant increase of the surface layer hardness of the material. The highest surface layer hardness, equal to 71.6 HRC, shows the material austenitized at the temperature 1120şC, hardened and tempered twice at the temperature 530oC. Practical implications Developed material is tested for turning tools. Originality/value: The material presented in this paper has layers consisting of the carbide-steel with growing hardness on one hand, and the high-speed steel, characterized by a high ductility on the other.

8

Effect of the sintering parameters on structure of the gradient tool materials

Dobrzański L. A., Hajduczek J., Kloc-Ptaszna A.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 36, nr 1

33-40

EN

Purpose: The purpose of this work was to obtain gradient tool materials, based on the unalloyed steel reinforced with HS6-5-2 high-speed steel, through using the conventional powder metallurgy method and sintering in the vacuum furnace at the range of temperature from 1190°C to 1250°C, in steps of 20°C, for 30 and 60 minutes. Design/methodology/approach: In presented work gradient materials were obtained through powder metallurgy consisting uniaxial compacting method and sintering. The unalloyed steel was fabricated by mixing iron and graphite powders. Structural examinations were carried out by optical microscopy methods assisted with the computer image analysis, scanning electron microscopy and X-ray microanalysis. Findings: It was found out, that increase of the sintering temperature contribute to the undergo coagulation on the grain boundary or creation of the large allocations on the grain boundary of the carbides in the matrix. As well, it was proved, that incompleted sintering process was caused by too low sintering temperature. Practical implications: Such gradient material may be applied for turning tools. Originality/value: A forming methods were developed for unalloyed steel and high-speed steel powders, which made it possible to obtain specimens with six layers in its structure. The material presented in this paper has layers, at one side consisting unalloyed steel and at the other side high-speed steel. The layers inside the material are mixes of the high-speed steel and unalloyed steel powders in the relevant proportions.

9

Gradient tool WC/HS6-5-2 materials produced using the powder metallurgy method

Dobrzański L., Kloc-Ptaszna A., Matula G.

Archives of Materials Science and Engineering

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2008

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Vol. 31, nr 1

9-12

EN

Purpose: The goal of this work is development of the new group of the gradient cermets with the high-speed steel matrix, reinforced with the hard carbides phases of the WC types. Design/methodology/approach: The materials were fabricated using the conventional powder metallurgy method, consisting in compacting the powder in a closed die, and subsequent sintering. All the sintered test pieces were subjected to examination of density and hardness; observations were also made using the scanning electron microscope (SEM), equipped with the back-scatter electrons detector (BSE) and the dispersive energy analyser (EDAX D4). Findings: The density of the compacted and sintered test pieces grows along with the sintering temperature increase. The HRA hardness of the compacted and sintered test pieces grows along with the sintering temperature increase. It was noted that application of a longer sintering time results in slight hardness lowering. Practical implications: Developed material is tested for turning tools. Originality/value: The material presented in this paper has layers consisting of the carbide-steel with growing hardness on one side, and on the other side the high-speed steel, characterized by a high ductility.

10

The impact of production methods on the properties of gradient tool materials

Dobrzański L. A., Kloc-Ptaszna A., Matula G., Contreras J. M., Torralba J. M.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 24, nr 2

19-26

EN

Purpose: The goal of this work is to obtain the gradient materials based on the non-alloyed steel reinforced highspeed steel using the conventional powder metallurgy method and pressureless forming powder metallurgy. Design/methodology/approach: Forming methods were developed during the investigations for high-speed and unalloyed steel powders, making it possible to obtain materials with six layers in their structure. The non-alloyed steel was fabricated by mixing iron powders with graphite. Findings: It was found out, basing on the hardness tests, that the layer built of steel without any alloy elements demonstrates very low hardness in comparison with the transition layer and the HS6-5-2 high-speed layer. The density of the specimens rises with increasing temperature. It was also observed that porosity decreases along with the carbon content in these layers. Practical implications: It was noticed, that increase of the sintering temperature results in the uncontrolled growth and coagulation of the primary carbides and melting up to forming of eutectics in layers consisting of the high-speed steel. Developed material is tested for turning tools. Originality/value: The layers were poured in such way that the first layers consisted of the non-alloy steel and the last one from the high-speed steel, and were compacted next. The layers inside the material are mixes of the high-speed steel and non-alloy steel powders in the relevant proportions.

11

Structure and properties of gradient tool materials with the high-speed steel matrix

Dobrzański L. A., Kloc-Ptaszna A., Matula G., Torralba J. M.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 24, nr 2

47-50

EN

Purpose: This work concerns research on the structure and properties of gradient tool materials with the HS6-5-2 high-speed steel matrix reinforced by the tungsten carbide. Design/methodology/approach: The materials were fabricated using the conventional powder metallurgy method, consisting in compacting the powder in a closed die, and subsequent sintering. All the sintered test pieces were subjected to examination of density, porosity, and hardness; observations were also made using the scanning electron microscope (SEM), equipped with the back-scatter electrons detector (BSE) and the dispersive energy analyser (EDAX D4). Findings: The density of the compacted and sintered test pieces grows along with the sintering temperature increase. The porosity grows along with the WC content growth in the particular layers. It was observed that the sintering time has an effect on the porosity growth. The longer the sintering time is, the higher the porosity is. The HRA hardness of the compacted and sintered test pieces grows along with the sintering temperature increase. It was noted that application of a longer sintering time results in slight hardness lowering. Practical implications: Developed material is tested for turning tools. Originality/value: The material presented in this paper has layers consisting of the carbide-steel with growing hardness on one side, and on the other side the high-speed steel, characterized by a high ductility.

12

Effect of WC concentration on structure and properties of the gradient tool materials

Dobrzański L. A., Kloc-Ptaszna A., Dybowska A., Matula G., Gordo E., Torralba J. M.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 20, nr 1-2

91-94

EN

Purpose: The goal of this work is to obtain the contemporary gradient materials based on the tungsten carbide reinforced high-speed steel using the conventional powder metallurgy method and increasing the high-steel hardness (80 HRA = 800 HV) by introducing the tungsten carbide as the reinforcing phase, with hardness exceeding 2200 HV. Design/methodology/approach: The materials were fabricated with the conventional powder metallurgy method consisting in compacting the powder in the closed die and finally sintering it. Forming methods were developed for powders of the HS6-5-2 high speed steel and WC, making it possible to obtain material with seven layers in the structure. Findings: It was found out basing on the microhardness tests that hardness of test pieces grows along with the sintering temperature and with WC content in the interface layers and in the high-speed steel ones. It was also observed that porosity decreases along with the WC concentration increase in these layers. It was found out, basing on the comparison of structures and properties of the compacted and sintered test pieces, that in structures of all examined test pieces in the sintered state fine carbides occurred distributed homogeneously in the high-speed steel layer. Research limitations/implications: It was noticed, that increase of the sintering temperature results in the uncontrolled growth and coagulation of the primary carbides and melting up to forming of eutectics in layers consisting of the high-speed steel. Practical implications: Material presented in this paper has layers consisting on one side from the mix of the high-speed steel and WC, and on the other side the high-speed steel, characteristic of the high ductility. Such material is tested for milling cutters. Originality/value: The layers were poured in such way that the surface layer consists of the mix of the high-speed steel and WC, and the middle one from the high-speed steel. The layers inside the material are mixes of the high-speed steel and WC in the relevant proportions.

13

Characteristics of structure and properties of a sintered graded tool materials

Dobrzański L. A., Kloc-Ptaszna A., Matula G., Torralba J. M.

Inżynieria Materiałowa

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2007

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Vol. 28, nr 3-4

138-141

EN

The goal of this work is the characterization of structure and properties of a graded tool materials. The materials were fabricated by using the conventional powder metallurgy method, consisting in compacting the powder in a closed die and sintering it. Forming methods were developed for the HS6-5-2 high-speed steel and non-alloy steel powders, making it possible to obtain materials with six layers in their structure. The powders were poured into the die so that the first layer consisted of the non-alloy steel and the last one consisted of the high-speed steel. The layers inside the material are mixes of the high-speed steel and non-alloy steel powders in relevant proportions. The pieces were sintered at the same temperature and over the same time, but in different atmospheres. The sintered parts were subjected to examinations of density, porosity, and Vickers and Rockwell hardness. Observations were also made, using the scanning electron microscope (SEM) equipped with the back-scatter electrons detector (BSE) and dispersive energy analyser (EDAX D4).

PL

Celem niniejszej pracy jest scharakteryzowanie struktury i własności narzędziowych materiałów gradientowych. Do wytwarzania materiałów została zastosowana konwencjonalna metoda metalurgii proszków polegając na prasowaniu proszku w matrycy zamkniętej i następnym spiekani Opracowano metody formowania proszków stali szybkotnącej typu HS6-5-i stali niestopowej, umożliwiające otrzymanie materiału z sześcioma warstwami w strukturze. Warstwy były wsypywane do matrycy w ten sposób, że pierwsza warstwa składa się ze stali niestopowej, a ostatnia ze sta szybkotnącej. Warstwy wewnątrz materiału są mieszaninami proszków stali szybkotnącej i stali niestopowej, w odpowiednich proporcjach. Próbki spiekano w tej samej temperaturze i czasie, lecz w innej atmosferze. Spieki poddano pomiarom gęstości, porowatości i twardości w skali Vickersa i Rockwella oraz przeprowadzono obserwacje na elektronowym mikroskop skaningowym (SEM) wyposażonym dodatkowo w detektor elektronów wstecznie rozproszonych (BSE) i analizator energii dyspersyjnej (EDAX D4).

14

Structure of the gradient carbide steels of HS 6-5-2 high-speed steel matrix

Dobrzański L. A., Kloc-Ptaszna A., Matula G., Torralba J. M.

Archives of Materials Science and Engineering

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2007

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Vol. 28, nr 10

589-592

EN

Purpose: The goal of this work is to obtain gradient carbide steels based on a high-speed steel reinforced with tungsten carbide. Design/methodology/approach: The materials were fabricated using the conventional powder metallurgy method. The gradient carbide steels was fabricated by mixing high-speed steel with WC powders. The uniaxial pressing before sintering was used for manufacturing the materials, consisting in compacting the powder in a closed die, and subsequent sintering. The sintered test pieces observations were also made using the scanning electron microscope (SEM), equipped with the back-scatter electrons detector (BSE) and the dispersive energy analyser (EDAX D4). Findings: It was observed that the as-sintered properties of gradient carbide steels are strongly affected by the tungsten carbide content. Practical implications: Developed material is tested for cutting tools. Originality/value: The material presented in this paper has layers, at one side consisting of the high-speed steel, characterized by a high ductility and at the other side the carbide steel characterized by a higher hardness. A forming methods were developed for high-speed and WC powders, making it possible to obtain materials with seven layers in their structure.

15

Structure and properties of the gradient tool materials of unalloyed steel matrix reinforced with HS6-5-2 high-speed steel

Dobrzański L. A., Kloc-Ptaszna A., Matula G., Torralba J. M.

Archives of Materials Science and Engineering

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2007

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Vol. 28, nr 4

197-202

EN

Purpose: The goal of this work is to obtain the gradient materials based on the non-alloyed steel reinforced highspeed steel using the pressureless formed method. Design/methodology/approach: The non-alloyed steel was fabricated by mixing iron powders with graphite. The unalloyed steel contains 0.5% carbon. The pressureless powder forming was used for manufacturing the materials. Findings: It was found out, basing on the hardness tests, that the layer built of steel without any alloy elements demonstrates very low hardness in comparison with the transition layer and the HS6-5-2 high-speed layer. It was also found, that the density rises with increasing temperature. The portion of pores in the particular layers of the gradient materials decreases along with the carbon concentration increase in particular layers. Practical implications: The material presented in this paper has layers, at one side consisting of the nonalloy steel with hardness growing with the increase of carbon content, and at other side the high-speed steel, characterized by a high ductility. Developed material is tested for turning tools. Originality/value: A forming methods were developed for high-speed and non-alloy steel powders, making it possible to obtain materials with three layers in their structure. Investigations included determining the sintering conditions, especially the temperature and treatment cycle, as well as examining selected mechanical properties.

16

Wpływ stężenia węgla na strukturę i własności gradientowych materiałów narzędziowych

Dobrzański L. A., Kloc-Ptaszna A., Matula G., Torralba J. M.

Archiwum Odlewnictwa

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2006

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R. 6, nr 21/1

141-148

PL

Celem niniejszej pracy jest opracowanie nowoczesnych materiałów gradientowych z wykorzystaniem konwencjonalnych metod metalurgii proszków, w celu zapewnienia wymaganych własności i struktury projektowanego materiału. Prezentowany materiał gradientowy posiada z jednej strony warstwę ze stali niestopowej, a z drugiej strony - warstwe ze stali szybkotnącej, charakteryzującej się dużą ciągliwością. Pomiędzy nimi znajdują sie warstwy przejściowe o wzrastającej zawartości węgla (twardości). Materiał taki testowany jest na noże tokarskie.

EN

The goal of this project is development of the contemporary gradient materials using the powder metallurgy methods to ensure the required properties and structure of the designed material. Material presented in this paper has layers consisting on one side from the non-alloy steel with hardness growing with the increase of carbon content, and on the other side the highspeed steel, characteristic of the high ductility. Such material is tested for turning tools.