25 results on '"Metallpulver"'
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2. Moisture in Metal Powder and Its Implication for Processability in L-PBF and Elsewhere.
- Author
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Mellin, Pelle, Rashidi, Masoud, Fischer, Marie, Nyborg, Lars, Marchetti, Lorenzo, Hulme-Smith, Christopher, Uhlirsch, Markus, and Strondl, Annika
- Abstract
Copyright of BHM Berg- und Hüttenmännische Monatshefte is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...
- Published
- 2021
- Full Text
- View/download PDF
Catalog
3. Effects of Al-Ni powder addition on dissimilar friction stir welding between AA7075-T6 and 304 L.
- Author
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Muhamad, M. R., Jamaludin, M. F., Yusof, F., Mahmoodian, R., Morisada, Y., Suga, T., and Fujii, H.
- Subjects
- *
FRICTION stir welding , *ALUMINUM alloys , *POWDERS , *INTERMETALLIC compounds , *ELECTRON microscopes - Abstract
Friction stir welding between AA7075-T6 aluminum alloy and 304 L stainless steel sheet metal was performed with the addition of Al-Ni powder between the joining interfaces to increase the joining performance. The welding tool was rotated at 200 min 1 to 800 min-1 with the constant traverse speed of 25 mm/min. The resulting joint interfaces were analyzed using a field emission-scanning electron microscope and energy-dispersive x-ray spectroscopy analysis. The tensile strength was greater for the Al-Ni powder added specimens at the lower tool rotational speeds. The tensile strength of 360 MPa was obtained for the 'with-powder' specimen as compared to 220 MPa for the 'without-powder' specimen at the 200 min-1 tool speed. Electron microscope images of the stir zone showed a significant mixing of the Al-Ni powder with the base materials, increased contact at the interface, which resulted in increased joining strength at the lower tool rotational speeds. However, based on the images, intermetallic compound that may contribute to the joining strength in the vicinity of the interfacial region was not detected. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
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- View/download PDF
4. Abrasion resistance of blended polymers filled with metallic powders.
- Author
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Mahmoud, M. M. and Ali, W. Y.
- Subjects
- *
ABRASION resistance , *POLYMERS , *METALLIC surfaces , *MECHANICAL wear , *FRICTION - Abstract
Friction and wear of polymeric composites formed by blending polyethylene (PE) and polymethylmethacrylate (PMMA) filled with different metallic powders is discussed in the present work. The scratch test was carried out to investigate wear resistance and friction coefficient of the tested composites prepared by molding of polymeric blends. Wear was measured by the net area of the cross section of the groove caused by the scratch and friction coefficient was measured as the ratio between the tangential and normal force exerted during scratch process. The test results showed that the best blend was 25 % polyethylene and 75 % polymethylmethacrylate with addition of bronze caused significant decrease in friction and wear. Increasing cooling rate of polymeric composites increased plasticization and consequently wear decreased. The strong adhesion of silicon carbide and bronze in the polymeric matrix caused significant wear decrease. [ABSTRACT FROM AUTHOR] more...
- Published
- 2017
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5. Verwendung von Drehrohröfen in der Bergbauindustrie.
- Author
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Waitz, R., Windsheimer, H., Wübben, P., and Yukhno, V. V.
- Abstract
Copyright of BHM Berg- und Hüttenmännische Monatshefte is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...
- Published
- 2015
- Full Text
- View/download PDF
6. Design and installation of internet-connected datalogger for continous sintering furnace : Development and implementation of Raspberry Pi based internet-connected datalogger, and generation of solutions for weight measuring
- Author
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Nygårds, Erik and Oliw, Martin
- Subjects
Product development ,Produktutveckling ,metallpulver ,internetuppkopplad datalogger ,Annan maskinteknik ,datalogger ,sintering furnace ,metal powder ,sintringsugn ,internet-connected datalogger ,Other Mechanical Engineering - Abstract
Höganäs AB has a customer center where they perform their cutomers production processes usingtheir own metal powder, thereby gaining knowledge of how the powder behaves and how it can be improved. The powder is usually pressed, and then sintered in a sintering furnace where temperature and atmosphere composition gives the component its desired characteristics. Höganäs AB didn’t save the parameters from these process’s in a easily accessible way, some values were not saved at all. To increase understanding of these parameters impact on the produced detail they wanted these parameters collected and stored in the cloud. They also wanted solution ideas and concepts for implementation of weight measuring on both the in- and output side of the furnace. This project used Ulrich & Eppinger’s product development method, modified by performing continous testing parallell to the design process. The project was also separated into three parts worked on simultaneously. Computer architecture, physical casing and weight measuring. To compile and upload to the cloud a Raspberry Pi 3 B+, a micro processor, was used. It connected via WiFi to upload files to OneDrive. The measured values from the furnace were gathered from the furnace’s PLC via OPCUA and a gas measuring unit via serial communication. Because of the use of metal powder there was conductive dust in the air which could lead to leakage currents and short circuiting if it were to gather on the processor unit. Hence the dust had to be keptaway. The casing was therefore designed to be relatively airtight. The casing was made with 3D-printed PETG. The seal utilized PETG’s elasticity to elastically deform an elevated seal, and thereby sealing the casing, without having to produce more components than a bottom and a lid. The cable feedthrough used the cables elastic deformation to seal. A screen was implemented to start and stop logging processes, which was also sealed using an overlapping lip around it’s rim. The logging of the furnace parameters was split in two logs, a day-log and a job-log. The daylog took measurements continously over a day in long intervals, 30 minutes. At the end of the day a log was uploaded for that day, hence the name. The job-log had to be started manually via the screen and was used to take measurements with higher frequency during a production series. Log files of both types were uploaded to a OneDrive folder. The product was tested with a number of final tests, both for the casing and the software. The casing was tested primarily for the numerical requirements set in the requirements specification. While the software was tested over a longer period of time to ensure functionality.The final product was a sealed, robust, easily disassembled and cable strain relieved 3D-printed box with a 3.5 inch touchscreen and a connected keyboard. It collected the desired data and compiled it to log files readable by programs such as Microsoft Excel. The weight measuring concept produced was a self-made solution with load cells under the loading ramp. The weight is then measured automatically during the regular loading process without disrupting it. Two backup solutions were also put forward. more...
- Published
- 2021
7. Modelling the influence of porosity on fatigue strength of sintered steels
- Author
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Hall, Emily
- Subjects
porosity ,metallpulver ,PM ,fatigue strength ,utmattning ,sintring ,sintered steels ,Chemical Engineering ,brottmekanik ,metal powders ,fatigue limit ,fracture mechanics ,Powder metallurgy ,porositet ,Kemiteknik ,Metallurgy and Metallic Materials ,pulvermetallurgi ,Metallurgi och metalliska material ,Fatigue ,utmattningsgräns - Abstract
The pores in pressed and sintered components constitute weak points in the material since the stress concentration is larger than the nominal stress there. Therefore, fatigue cracks initiate at the pores. Specifically, it can be assumed that the fatigue cracks initiate at the largest pore in the stressed volume. Studies have previously looked at finding ways to model the fatigue strength of the material based on the largest pore. This thesis looks at a model previously derived for hardened pressed and sintered materials that is based on linear elastic fracture mechanics and investigates if said model can be modified to include non-hardened pressed and sintered materials that do not necessarily behave linear elastically. A model describing the influence of the size of the largest pore on the fatigue limit using empirical coefficients is suggested. Furthermore, the area of the largest pore is modelled using extreme value statistics. The model proved successful in modelling the density effect of the porosity on the fatigue strength for two materials with different microstructures: one with a homogeneous microstructure and one with a heterogeneous microstructure. For the material with the homogenoeous microstructure the model also accounted well for the notch effect when tested on samples with a different geometry. However, for the heterogeneous material the model did not account for the notch effect. Deformation hardening due to local plastic deformation in the softer phases was suggested as a possible explanation and was supported by tensile tests. more...
- Published
- 2019
8. Entwicklung kriechfester Titanaluminid-Legierungen für das Metallpulverspritzguss-Verfahren
- Author
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Soyama, Juliano
- Subjects
Kriechen ,Titanaluminide ,Spritzgießen ,ddc:673 ,Metallpulver - Abstract
Titanium aluminides show great technological potential due to their light weight and excellent creep resistance. Their utilisation thus offers a potential to decrease fuel consumption and simultaneously improve the performance of components subjected to stress at high temperatures. However, shaping of titanium aluminides is still a very challenging and costly task considering their brittleness and the sensitivity on chemical composition. Therefore powder metallurgy near-net shape manufacturing techniques are very attractive to decrease material waste and reduce overall processing costs. This research work was focused on the preparation, characterisation and optimisation of creep resistant titanium aluminides for the Metal Injection Moulding (MIM) process. Considering the little information available regarding processing of titanium aluminides by MIM, this work had firstly the goal of assessing the creep behaviour of a reference titanium aluminide alloy. Secondly, alloy variations with compositions based on the reference material were designed with the objective of improving the creep resistance, especially concerning primary creep. The basic strengthening mechanisms applied involved the addition of slow diffusing elements and elements that cause precipitation of hard particles. The specimens were prepared by using pre-alloyed powder and mixtures of a master alloy (pre-alloyed) and elemental powders. Consequently, a great deal of effort was spent in the characterisation of the sintering behaviour in order to achieve reliable test pieces. Even though both methods can deliver sound specimens, the pre-alloyed powder approach led to the best results in terms of residual porosity and microstructural homogeneity. The mechanical testing results indicate that processing of titanium aluminides by MIM is feasible and acceptable creep properties can be achieved with the proper sintering parameters. Even though the ductility at room temperature was considerably limited due to the residual porosity and high amounts of impurities intrinsic to the MIM process, alloys developed within this study showed improved primary creep resistance in the high stress – high temperature regime. In particular alloy variations containing additions of Mo, Si and Gd led to a considerable improvement of the primary creep resistance in comparison to the reference material at 800°C – 350 MPa loading. Titanaluminide zeigen ein großes technologisches Potenzial durch ihre geringe Dichte und hervorragende Kriechfestigkeit. Deswegen kann durch ihre Verwendung der Kraftstoffverbrauch reduziert und gleichzeitig die Gesamtleistung von mechanisch belasteten Hochtemperaturkomponenten verbessert werden. Die Formgebung von Titanaluminiden ist jedoch noch ein sehr schwieriger und kostenintensiver Prozess, vor allem aufgrund der Sprödigkeit und der starken Abhängigkeit der Eigenschaften von der chemischen Zusammensetzung. Daher sind pulvermetallurgische „near-net shape“ Fertigungstechniken sehr attraktiv in Bezug auf Reduzierung des Materialabfalls und der Gesamtverarbeitungskosten. Inhalt diese Arbeit war die Herstellung, Charakterisierung und Optimierung von kriechfesten Titanaluminiden für das Metallpulverspritzguss-Verfahren (Metal Injection Moulding – MIM). Angesichts der wenigen existierenden Informationen über die Verarbeitung von Titanaluminiden durch MIM war das erste Ziel dieser Arbeit die Ermittlung des Kriechverhaltens einer Referenz-Titanaluminid-Legierung. Zweitens wurden Legierungsvarianten auf Basis des Referenzmaterials mit dem Ziel der Verbesserung der Kriechfestigkeit hergestellt, insbesondere in Bezug auf primäres Kriechen. Das Design der Legierungsvarianten basierte dabei auf der Anwendung folgender grundlegender Verstärkungsmechanismen: Zugabe von langsam diffundierenden Elementen und von Elementen, die härtende Ausscheidung bilden können. Die Proben wurden entweder aus vorlegierten Pulvern oder Mischungen aus einer Masterlegierung (vorlegiert) und Elementarpulvern hergestellt. Um eine Überlagerung von fertigungsbedingten Faktoren, wie hohe Porosität, auf die ermittelten mechanischen Eigenschaften auszuschließen, wurde zuerst eine intensive Charakterisierung des Sinterverhaltens durchgeführt. Obwohl mit beiden Methoden geeignete Proben herstellbar waren, führte die Verwendung von vorlegierten Pulvern zu den besten Ergebnissen in Bezug auf Restporosität und Gefüge-Homogenität. Die Ergebnisse der mechanischen Versuche zeigen, dass die Verarbeitung von Titanaluminiden durch MIM möglich ist und eine mit etablierten Herstellungsverfahren konkurrenzfähige Kriechfestigkeit mit den richtigen Sinterparametern erreicht werden kann. Obwohl sich die mit dem MIM Verfahren verbundene Restporosität und den relativ hohen Gehalt an Verunreinigungen negativ auf die Raumtemperaturduktilität auswirkten, zeigten die neuen Legierungen eine verbesserte primäre Kriechfestigkeit im Bereich hoher Spannungen und Temperaturen. Insbesondere die Legierungsvarianten, die Zusätze von Mo, Si und Gd enthalten, führten zu einer erheblichen Verbesserung der primären Kriechbeständigkeit im Vergleich zum Referenzmaterial bei 800°C und 350 MPa Belastung. more...
- Published
- 2014
9. Metallspritzgießen von Titan-Niob Legierungen für Biomedizinische Anwendungen
- Author
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Zhao, Dapeng
- Subjects
Spritzgießen ,Sintern ,Titanlegierung ,Nioblegierung ,Metallpulver ,ddc:620 - Abstract
The main subject of this work was the investigation of sintering behavior, microstructure, mechanical properties and biocompatibility of metal injection moulded (MIM) Ti-Nb alloys for biomedical applications. Commercially pure titanium (CP-Ti) samples were also fabricated by MIM as a reference. The sintering behavior of MIM Ti-Nb alloys was studied at first, in order to roughly determine the sintering parameters in the following investigations. Dilatometry was applied to investigate the linear shrinkage of MIM Ti-Nb samples from room temperature to 1500 °C at a heating rate of 3 °C/min under argon atmosphere. Various sintering parameters and Nb contents were used to investigate their influences on microstructure and mechanical properties of MIM Ti-Nb alloys by means of density measurements, optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM) and mechanical testing. Transmission electron microscopy (TEM) and high energy X-ray diffraction (HEXRD) measurement were applied to investigate the nature and precipitation of the unexpected titanium carbide precipitates in MIM Ti-Nb alloys. Initial cell adhesion and cell proliferation assays of human umbilical cord perivascular cells (HUCPV) on MIM Ti-Nb alloys were performed for biocompatibility characterization. The results of this work show that MIM Ti-Nb and MIM CP-Ti samples have been successfully fabricated and the as-sintered samples show good shape retention without distortion compared to the green sample. The sintering process of MIM Ti-Nb alloys consists of three main steps – Ti-diffusion step, Ti-Nb-diffusion step and Matrix-diffusion step. With increasing sintering temperatures and time, MIM Ti-Nb alloys exhibit lower porosity and higher Young’s modulus. A higher Nb content in MIM Ti-Nb alloys leads to an increase of carbide area fraction and porosity. The three factors – Nb content, carbide area fraction and porosity – determine the mechanical properties of MIM Ti-Nb alloys. An increase of Nb content and amount of carbides as well as a lowered porosity lead to a higher tensile strength. A decrease of Young’s modulus can be expected with higher Nb content and porosity. A high amount of titanium carbides can result in very poor ductility, but annealing and quenching process can significantly improve the elongation by dissolving the carbides. MIM Ti-Nb alloys exhibit good biocompatibility, indicating their potential for implant applications. Das Hauptthema dieser Arbeit war die Untersuchung von Sinterverhalten, Mikrostruktur, mechanischen Eigenschaften und Biokompatibilität von mittels Metallpulverspritzguss (MIM: Metal Injection Moulding) verarbeiteten Ti-Nb Legierungen für biomedizinische Anwendungen. Reintitan (CP-Ti) Proben wurden ebenfalls mittels MIM als Referenz hergestellt. Zunächst wurde das Sinterverhalten der MIM Ti-Nb Legierungen untersucht, um die Sinterparameter für die folgenden Untersuchungen abzuschätzen. Dilatometrie wurde angewendet, um die lineare Schrumpfung von MIM Ti-Nb Proben beim Aufheizen von Raumtemperatur auf 1500 °C mit einer Rate von 3 °C/min unter Argon Atmosphäre zu untersuchen. Verschiedene Sinterparameter und Nb-Gehalte wurden verwendet, um deren Einflüsse auf die Mikrostruktur und die mechanischen Eigenschaften von MIM Ti-Nb Legierungen mit Hilfe von Dichtemessung, optischer Mikroskopie (OM), Röntgenbeugung (XRD), Rasterelektronenmikroskopie (REM) und mechanischer Prüfung zu bestimmen. Transmissionselektronenmikroskopie (TEM) und Hochenergie-Röntgenbeugung (HEXRD) wurden angewendet, um Art und Ausscheidungsprozess der unerwarteten Titankarbide in MIM Ti-Nb Legierungen zu untersuchen. Zur Charakterisierung der Biokompatibilität wurden Tests bezüglich anfänglicher Zelladhäsion und Zellproliferation von perivaskulären Zellen der menschlichen Nabelschnur (HUCPV) auf der Oberfläche von MIM Ti-Nb Legierungen durchgeführt. Die Ergebnisse dieser Arbeit zeigen, dass MIM Ti-Nb und MIM CP-Ti Proben erfolgreich hergestellt werden können. Die gesinterten Proben zeigten eine gute Formbeständigkeit ohne Verzerrung gegenüber des Grünteils. Der Sintervorgang der MIM Ti-Nb Legierungen besteht aus drei Hauptschritten – Ti-Diffusionsschritt, Ti-Nb-Diffusionsschritt und Matrix-Diffusionsschritt. Mit zunehmender Sintertemperatur und Zeit zeigen MIM Ti-Nb Legierungen eine abnehmende Porosität und eine Erhöhung des E-Moduls. Ein höherer Nb Gehalt führt zu einer Erhöhung der Flächenanteile von Karbiden und Poren. Die drei Faktoren – Nb Gehalt, Karbid-Flächenanteil und Porosität – kontrollieren die mechanischen Eigenschaften von MIM Ti-Nb Legierungen. Eine Erhöhung des Nb-Gehaltes und der Menge der Karbide sowie eine geringere Porosität führen zu einer höheren Zugfestigkeit. Eine zusätzliche Verringerung des E-Moduls findet mit höherem Nb-Gehalt und höherer Porosität statt. Eine große Menge an Titankarbiden führt zu einer niedrigen Duktilität, jedoch kann die Dehnung durch Glühen und Abschrecken zur Auflösung der Karbide deutlich verbessert werden. MIM Ti-Nb Legierungen weisen eine gute Biokompatibilität auf und zeigen dadurch ihr großes Potenzial für Implantat Anwendungen. more...
- Published
- 2014
10. Abschlussbericht zum Wachstumskern Thale PM : Verbundprojekt 5: Entwicklung innovativer Metallpulver für zukunftsorientierte Werkstoffe (Innopulv), Teilprojekt 2: Charakterisierungen sowie mechanische und thermische Behandlungen innovativer Metallpulver ; Laufzeit: 01.11.2008 - 31.10.2011
- Author
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Fraunhofer-Institut Für Fertigungstechnik Und Angewandte Materialforschung
- Subjects
Metallische Werkstoffe: Allgemeines ,Herstellung ,Heißgas ,Chemical and environmental engineering ,Metallpulver ,Verdüsung ,Mechanische Verfahrenstechnik ,Materials science - Abstract
Ill., graph. Darst.
- Published
- 2012
- Full Text
- View/download PDF
11. Spritzgießen von Biomaterialien bietet neue Perspektiven
- Author
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Imgrund, Philipp, Hein, Sebastian Boris, Friderici, Vera, and Publica
- Subjects
Bioverträglichkeit ,medizinische Technik ,Implantat ,Porosität ,Metallpulver ,Calciumphosphat ,Spritzgießverfahren ,Mikrostruktur ,Titan ,Biomaterial ,Gewebeverträglichkeit - Abstract
Das Mikro-Metallpulver-Spritzgussverfahren hat sich als ein geeignetes Verfahren zur Herstellung von regelmäßig angeordneten Mikrostrukturen auf Implantat-Oberflächen erwiesen, wobei eine Nachbearbeitung entfallen kann und sich definierte Dichten und Porositäten realisieren lassen. Das Zellwachstum kann auf Grund der Regelmäßigkeit der erzeugten Oberflächen gezielt an die konkrete Anwendung angepasst werden. Das in einer Studie eingesetzte Pulver besteht aus einer Mischung aus Nano- und Mikropartikeln mit Durchmessern von 15 nm bis 5 Mikrometer. Ein weiteres Ziel ist die Verarbeitung von biokompatiblem Titan. Beispiele werden vorgestellt, wie Interferenzschrauben, Teile mit Halbschalen-Oberfläche, Osteoplast-Zelle zwischen Hemisphären und medizinischen Implantaten bei Knochenbrüchen über das Bone Tissue Engineering mit einem Komposit aus Calciumphosphat. more...
- Published
- 2010
12. Stabilisierung von Korrosionsschutzpigmenten
- Author
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Brinkmann, A., Zockoll, A., and Publica
- Subjects
Polypyrrol ,chemische Stabilisierung ,Chelatbildung ,kathodischer Korrosionsschutz ,Wasserlack ,Magnesium ,Metallpulver ,Zink ,Korrosionsschutzüberzug ,Metallpigment ,Kern-Schale-Verbundwerkstoff ,Epoxidharz - Abstract
Die Zinkstaubgrundierung ist ein bewährter kathodischer Korrosionsschutz des Stahls für Schiffsbau und Offshore-Anlagen und entsprechende Magnesiumpigmente sollen nun Aluminiumlegierungen schützen, beispielsweise im Flugzeugbau. Für wasserlösliche Anstrichmittel (VOC-Minderung) müssen die Metallstäube gegenüber dem Wasser stabilisiert werden. Chelatkomplexbildende Epoxidharze stabilisieren Magnesiumpigmente und Zinkpigmente in wasserverdünnbaren Lacksystemen und erhalten gleichzeitig die kathodische Korrosionsschutzwirkung. Im Handel gibt es bereits entsprechende Epoxidharze und diese müssen nun so eingesetzt werden, dass sie die Metallpigmente komplexieren, aber nicht vollständig belegen. Eine zweite Möglichkeit sind koagulierende Mehrfachschutzschichten. Sie bestehen aus mehreren funktionellen Oligomeren, die von innen (Pigment) nach außen zunehmend hydrophober werden. Sie stabilisieren die Metallpigmente in wasserverdünnbaren Lacksystemen ebenfalls, die Stabilisierung ist aber geringer als die mit chelatkomplexbildenden Epoxidharzen. Eine Stabilisierung durch Abscheidung von Polypyrrol ist nur für Zinkpigmente möglich. Die Polypyrrolabscheidung ergibt eine sehr gute Stabilisierung. Ob die Korrosionsschutzwirkung der Pigmente erhalten bleibt, ist jedoch fraglich. more...
- Published
- 2010
13. Extrusion of metal powders by continuous powder extrusion
- Author
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Stadelmann, Claudia
- Subjects
Strangpressen ,Metallpulver ,ddc:620 ,Aluminiumlegierung ,Technische Fakultät -ohne weitere Spezifikation - Abstract
In den letzten Jahren ist das Interesse, kostengünstig Metallpulver zu kompaktieren, stark gestiegen. Bauteile aus pulvermetallurgisch hergestellten Werkstoffen werden in zunehmendem Maß in der Kraftfahrzeugindustrie, der Luft- und Raumfahrt sowie im allgemeinen Maschinenbau eingesetzt. Eine neue kostengünstige Alternative, um Metallpulver zu kompaktieren, stellt das kontinuierliche Strangpressen dar. Das Hauptanwendungsfeld dieser Technologie ist bisher die Umarbeitung von Gieß- oder Walzdraht aus Aluminium- oder Kupferlegierungen in komplexere Geometrien in einem Arbeitsschritt. Die Verarbeitung von Granulaten oder sogar Pulvern wird derzeit nur vereinzelt durchgeführt und ist daher großtechnisch nicht weit entwickelt. Die kontinuierliche Pulverstrangpresse besteht aus einem rotierenden Rad mit einer umlaufenden Nut und einem stationären Schuh, der als Werkzeugträger dient und eine Extrusionskammer bildet. Das Zuführmaterial wird aufgrund von Reibung in diese Kammer eingezogen. An einem Gegenhalter wird das Material zur Matrize hin abgelenkt. Die einzelnen Pulverpartikel verschweißen aufgrund von Scherkräften zu einem vollständig kompaktierten Strang. Die Reibungskräfte, die durch die Rotation des Extrusionsrades auftreten, erzeugen die erforderlichen Temperaturen und Drücke für die kontinuierliche Extrusion durch die Matrize. Im Rahmen dieser Arbeit werden experimentelle Untersuchungen zum kontinuierlichen Pulverstrangpressen von verschiedenen Aluminiumpulvern durchgeführt. Eine stabile Strangaustrittsgeschwindigkeit und Produktqualität wird erreicht, wenn die Prozessparameter wie Pulverzuführung, Extrusionsradgeschwindigkeit und Prozesstemperatur aufeinander abgestimmt sind. Das Zusammenspiel dieser Parameter ist sehr komplex. Daher wird zusätzlich ein numerisches Modell entwickelt, das den Materialfluss in der Extrusionskammer beschreibt. Zusätzlich wird mit der Finiten Differenzen Methode der Wärmehaushalt des Prozesses und der Extrusionsdruck berechnet. Anhand der experimentellen Untersuchungen und einer Para¬meterstudie am Modell werden grundlegende Erkenntnisse für die Prozessführung bei der Verarbeitung von Metallpulvern gewonnen. Over the past years the interest in compacting economically metal powder is extremely risen. Powder metal parts are used in a progressive rate in the automotive and aerospace industry as well as machine construction. Continuous powder extrusion is a new economically alternative to the conventional extrusion. Usually the continuous extrusion technology is a metal forming process for non-ferrous wires into complex geometries in a single step. A new approach is to use this process with particulate or powder feedstock as an alternative route to conventional powder extrusion which is currently not developed in an industrial scale. The continuous extrusion press consists of a rotating wheel which has a circumferential groove and a stationary shoe which incorporates the tooling and forms an extrusion chamber. The feedstock is drawn into the chamber by frictional grip. An abutment provides an end closure, arresting the forward motion of the feed and forcing the material to flow under right-angle. Discrete powder particles are welded together by shear forces and thus compacted to a fully dense solid. The frictional forces arising from continued wheel rotation generate the temperature and pressure required for continuous extrusion through the die. In this thesis laboratory experiments about continuous powder extrusion with different aluminium alloys are studied. A stable product velocity and quality is achieved if tooling setup and process parameters like powder feeding, wheel speed and process temperatures are optimised. In fact continuous powder extrusion is quite complex. In order to get an insight into the interaction of the various process parameters a model has been developed to describe the material flow in the Conform-extrusion chamber. Additional the heat balance of the process and the extrusion pressure is modelled using a finite difference method. The boundary values of the model are varied and the results are compared to experimental results. more...
- Published
- 2009
14. Zusammenhang zwischen der Porenmorphologie und der Schwingfestigkeit von Sinterstahl und Sintereisen
- Author
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Dalgiç, Münip and Beiss, Paul
- Subjects
Porenmorphologie ,Feret ,Dauerschwingfestigkeit ,Verteilungsfunktion ,Porosität ,geometrische Merkmale ,microstructure ,Quantitative Bildanalyse ,Bruchmechanik ,Zugfestigkeit ,metallography ,Dehngrenze ,Ingenieurwissenschaften ,%22">Gefüge ,Sintern ,Formfaktor ,pore morphology ,Metallpulver ,Schwingfestigkeit ,fatigue ,ddc:620 ,Metallographie - Abstract
Within this work the relationship between the pore morphology and the fatigue properties of sintered pure iron and steel has been investigated. The mechanical properties of P/M are controlled by their microstructure and the porosity. Many parameters are influencing the microstructure and the porosity. A few of these parameters were considered in the investigation, which will have a significant influence on the performance characteristics of the materials. These parameters are the density, the kind of the powder, the sinter temperature and technique of alloying as well as the composition. The density acts as main parameter because it includes all other parameters. Therefore, the density has the maximum potential for optimizing the properties of the sintered components. The above mentioned parameters influence the morphology of the pores. Due to this, the characterizing of the pore characteristics is very important. The mechanical properties and the porosity have been investigated by varying the density, the sintering temperature and basic powder for sintered pure iron and alloyed steel. The investigated materials were Distaloy AE and SE, pure iron ABC 100.30 and MH 65.17. Basic powder was water atomized and pure broken sponge iron. The sintering conditions were 1120°C and 1280°C in an atmosphere of 70% N2 and 30% H2 in industrial equipment. If the relationship between the geometrical features of the pores and the influencing parameters is known, it is possible to optimize the morphology of the pores by the influencing factors. The base characteristics are pore area and perimeter, convex perimeter, maximum and minimum pore dimensions and the intercepts or distances between the pores. From the primary data a huge variety of secondary quantities can be derived which are used to describe the pore size, the pore shape, and pore interpore space. The pore morphology was quantified by image analysis. According to the results of the image analysis, the majority of all pores is small and rather round. Only a few large pores which are automatically also very irregular can act as potential fracture initiation sites. For this reason 98% of all pores were excluded from the further processing. Only 2% of the remaining larger and most irregular pores were evaluated. Pore irregularities are commonly characterized by a shape factor. The bending fatigue strength was investigated for a varying density by different sintering temperatures and basic powders. For each experimental condition 60 specimens were used in fully reversed flat bending tests at 6 stress levels of which 3 occurred in fracture. The endurance limits were determined for 50% probability at 107 cycles. Many properties of porous sintered materials are related to the pore microstructure. An attempt was made to correlate the fatigue behavior of industrially manufactured sintered iron and steels with quantitative pore characteristics. Crack initiation in fatigue tests was restricted to very few large irregular pores. All efforts to correlate average pore size or shape factors with fatigue strength values yield at best tendencies. Powder laws to describe the relationships between the strength, the density, and the shape factor the coefficients were calculated by regression analysis. more...
- Published
- 2009
15. Effect of SiC particles on the laser sintering of Al-7Si-0.3Mg alloy
- Author
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Dirk Godlinski, Abdolreza Simchi, and Publica
- Subjects
Materials science ,Silicon ,Alloy ,Composite number ,Kinetics ,chemistry.chemical_element ,schnelle Prototypentwicklung ,engineering.material ,law.invention ,Reaction rate constant ,Aluminium ,law ,General Materials Science ,Ceramic ,Composite material ,Laserstrahlsintern ,Aluminium-Silizium-Legierung ,Aluminiumsiliciummagnesiumlegierung ,Mechanical Engineering ,dispersionsgehärtete Legierung ,Metals and Alloys ,eutektisches Gefüge ,Condensed Matter Physics ,Selective laser sintering ,chemistry ,Mechanics of Materials ,visual_art ,engineering ,visual_art.visual_art_medium ,Metallpulver ,Siliciumcarbid - Abstract
The direct laser sintering of Al-7Si-0.3Mg/SiC composites was studied. It is shown that the densification rate obeys first-order kinetics. The rate constant is found to increase at low SiC fractions but abruptly decreases at larger than about 5 vol%. In the presence of ceramic particles, the melt track becomes more stable and a more continuous sintered surface is obtained. Meanwhile, significant reaction occurs between the aluminum melt and the reinforcement particles, leading to formation of Al4SiC4 and silicon particles. The solidification microstructure is also altered. Entnommen aus TEMA more...
- Published
- 2008
16. Multifunktionelle Leichtbauwerkstoffe - Auf Basis von zellularen metallischen Werkstoffen
- Author
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Stephani, G. and Publica
- Subjects
Energieabsorption ,Gewichtsverlust ,Molybdän ,Schicht=Belag ,Wärmeisolation ,metallischer Werkstoff ,Katalyse ,Leichtbauweise ,Energieübertragung ,Schallabsorption ,Hohlkugel ,Materialeinsparung ,Metallpulver ,Dämpfung - Abstract
Es werden auf Basis von zellularen metallischen Werkstoffen deren Vorteile beschrieben. Neben einer drastischen Gewichts- und damit Materialeinsparung können durch zellulare Werkstoffe weitere anwendungsspezifische Eigenschaften, die insbesondere durch die Zellstruktur bestimmt werden, wie Schallabsorption, Wärmeisolation, Energieabsorption, mechanische Dämpfung, Stoff- und Energietransport oder katalytische Effekte, realisiert werden. Zellulare metallische Werkstoffe können aus der flussigen, festen oder gasformigen Phase hergestellt werden. Am weitesten entwickelt sind derzeit die schmelzmetallurgischen Verfahren. Die Herstellung von metallischen Hohlkugeln erfolgt durch Metallpulverbeschichtung von vorwiegend organischen Trägerwerkstoffen (vorzugsweise Styroporkugeln) mit einem anschließenden Entbinderungs- bzw. Sintervorgang. Mit der entwickelten Technologie ist es möglich nahezu alle sinterbaren Pulver als Hohlkugeln (Durchmesserbereich ca. 1-12mm) herzustellen. Die Eigenschaften zellularer metallischer Werkstoffe werden im Wesentlichen durch den Basiswerkstoff sowie die Zellgröße, Zellmorphologie und die Gesamtporosität beeinflusst. Grundsätzlich skalieren die meisten Eigenschaften mit der Gesamtporosität der zellularen Struktur. Die bisher vorliegenden Untersuchungsergebnisse zeigen das zellulare Metalle vor allem ein gutes Energieabsorptionsvermögen, eine sehr gute Schallabsorption sowie gute Wärmedämmeigenschaften besitzen. So zeigten Untersuchungen zum Wärmeleitvermögen von Molybdän-Hohlkugelstrukturen bei einer Strukturdichte von 0,3 g/cm(exp 3) ca. 1 % des Wärmeleitfähigkeit vom kompakten Molybdän. Hierdurch eröffnen sich effizientere Möglichkeiten, z.B. durch die selbsttragenden Eigenschaften der Hohlkugelstrukturen für die Hochtemperaturisolation. more...
- Published
- 2007
17. Verfahren und Prozeßketten zur Fertigung metallischer Bauteile und Werkzeuge
- Author
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Klocke, F., Nöken, S., and Publica
- Subjects
Stereolithographie ,Laser-Generieren ,Metallgießverfahren ,Pulvermetallurgie ,Schichtaufbau ,Metallpulver ,Rapid Prototyping ,Musterteil ,Prototyp ,Lasersintern ,Modell ,Feinguß - Abstract
Verfahren und Prozeßketten zur Fertigung metallischer Bauteile und Werkzeuge Während die direkte Herstellung komplexer Modelle und Musterteile aus Kunststoff-, Papier- und Wachsmaterialien auf Basis von CAD-Daten bereits technisch realisiert ist, konzentrieren sich die gegenwärtigen Entwicklungsaktivitäten auf Verfahren und Prozeßketten zur Herstellung metallischer Bauteil- und Werkzeuggeometrien. more...
- Published
- 1995
18. Powder metallurgy on its way to nanocrystalline structures
- Author
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Günther, B., Kunze, H.-D., Scholz, B., and Publica
- Subjects
Pulvermetallurgie ,mechanisches Legieren ,Metallpulver ,nanokristallines Material - Abstract
A survey is given on some methods for the preparation of metallic and ceramic dense nanocrystalline materials with average grain sizes between 5 and 10O nm The use of nano-dispersed, i.e. highly sinter-active starting powders allows the realization of extremely high grain-/phase-boundary area that determine the unusual properties of the resultant P/M parts and materials. The various suitable P/M methods for the production of pure as well as composite nc- materials include the sol-gel process, mechanical alloying and the inert gas condensation method. Some of the fascinating potentials of P/M fabricated nc-materials due to their magnetic electronic and mechanical behaviour are elucidated more...
- Published
- 1993
19. Mechanical alloying reduces wear of self-lubricating materials
- Author
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Günther, B., Kunze, H.-D., Veltl, G., Takahashi, K., and Publica
- Subjects
brass ,wear ,graphite ,wear resistant material ,metal powder ,verschleißfester Werkstoff ,mechanical alloying ,Festschmierstoff ,Graphit ,powder metallurgy ,Messing ,Pulvermetallurgie ,lubricant ,Verschleiß ,mechanisches Legieren ,Metallpulver - Abstract
Powders of self-lubricating materials were produced by mechanical alloying in the systems brass / tungsten disulfide and brass / graphite. The development of microstructure during the mechanical alloying process was investigated. Homogeneous dispersions of graphite into the brass matrix could be achieved. The wear properties of such consolidated and sintered composites are reported more...
- Published
- 1993
20. Pore formation during reactive sintering of extruded titanium - aluminium powder mixtures
- Author
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F. Schmelzer, S. Schultrich, G. Leitner, W. Poessnecker, M. Dahms, and Publica
- Subjects
Materials science ,Kirkendall effect ,Annealing (metallurgy) ,Metallurgy ,Metals and Alloys ,Intermetallic ,chemistry.chemical_element ,Sintering ,Strangpressen (Metall) ,Condensed Matter Physics ,Microstructure ,Mikrogefüge ,Differential scanning calorimetry ,Kirkendall-Effekt ,chemistry ,Chemical engineering ,Sintern ,Materials Chemistry ,Metallpulver ,Physical and Theoretical Chemistry ,Powder mixture ,Titanium - Abstract
A powder mixture Ti-49 at.% Al was extruded at room temperature. Swelling due to phase transformation during annealing was studied using differential scanning calorimetry and dilatometry. It is the result of several processes: (i) Kirkendall pores during solid state interdiffusion, (ii) macro-pores during the reaction of liquid aluminium and solid titanium, (iii) inter-diffusion of Al 3 Ti and pure titanum forming the intermetallic phases γ-TiAl and α 2 -Ti 3 Al. Swelling is anisotropic due to the elongated titanium particles. Sintering occurs at higher temperatures depending on the microstructure after Al 3 Ti formation more...
- Published
- 1993
21. Preparation of nanocrystalline materials by PM methods
- Author
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Günther, B., Weiss, H., and Publica
- Subjects
Härte ,Pulvermetallurgie ,Nanopulver ,Edelgaskondensation ,Metallpulver ,nanokristallines Material - Abstract
Nanocrystalline solids (nc-) solids with average grain sizes less than 10Onm are most conveniently produced by powder metallurgical methods. This is especially true for reactive powders (e.g., refractive metals) and powder blends (alloys, composites), where mixtures of the components on a nanometer-scale are a prerequisite for obtaining a homogeneous product. We have used the inert gas evaporation as a method to produce and consolidate various elemental powders within a single device. The microstructure of the resulting nc-components (diameter in the range 20 ... 10Onm) have been correlated with the respective mechanical properties. In general, cold-consolidated ultrafine grained elemental metals are characterized by a remarkably high strength more...
- Published
- 1993
22. Secondary recrystallization effects in nanostructured elemental metals
- Author
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A. Kumpmann, B. Günther, H.-D. Kunze, and Publica
- Subjects
Thermoanalyse ,Materials science ,Rekristallisation ,Metallurgy ,General Engineering ,Recrystallization (metallurgy) ,Metallpulver ,Mikrogefüge ,mechanische Eigenschaft ,nanokristallines Material - Abstract
The thermal stability of ultrafine grained, elemental metal powder compacts (Cu, Ag, Pd) with low impurity content and high mass density were investigated by DSC and TEM measurements. In all our samples the crystallites grow abnormally. Grain growth is found to set in at temperatures below the recrystallization temperature known from coarse grained metals that have been heavily cold worked. For Cu and Pd even at ambient conditions abnormal grain growth occurs. Porosity up to 15% does not change grain growth temperature and abnormal grain growth behaviour. Gaseous impurities (oxygen) tend to stabilize the grain boundaries and enhance the effective activation energy for the grain growth process more...
- Published
- 1992
23. Fundamental aspects of the compaction of metal powders
- Author
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Eduard Arzt and Fischmeister, H.
- Subjects
Metallpulver ,Reibung ,ddc:620 ,Deformation - Abstract
The search for mathematical methods of predicting the increase in density of a metal powder during compaction has attracted numerous scientists, as it is both a technologically interesting and a scientifically challenging problem. This review outlines the way from simple curve fitting approaches to first attempts at constructing physical models which might form a rational basis for the improvement of powder compactibility or compaction procedures. The models described range from considerations of the deformation of a single spherical pore to reasoning in terms of the deformation behaviour of spherical particles in regular and - more recently - random packings. This paper will not deal with the way in which friction affects the distribution of pressure and density in a compact, nor with the effects of lubricants. more...
- Published
- 1979
- Full Text
- View/download PDF
24. Die Verdichtung von Keramik- und Metallpulvern sowie deren Mischungen durch Explosivdruck
- Author
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Prümmer, R. and Publica
- Subjects
Mischung ,Explosivdruck ,Keramikpulver ,Metallpulver ,Verdichtung - Published
- 1973
25. MECHANISMS OF HOT-ISOSTATIC PRESSING
- Author
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F. B. Swinkels, David Wilkinson, Eduard Arzt, and Michael F. Ashby
- Subjects
Pressing ,Continuous measurement ,Materials science ,Polymethylmethacrylate ,General Engineering ,chemistry.chemical_element ,Mechanics ,Plasticity ,Pulververdichtung ,Isostatisches Pressen ,chemistry ,Creep ,Hot isostatic pressing ,Forensic engineering ,Metallpulver ,ddc:620 ,Pulver ,Tin - Abstract
A press was built which allows densification to be measured continuously during isostatic pressing of powders at temperatures up to 200 degree C and pressures up to 20 MN/m**2. The press was used to study the densification of lead, tin, and PMMA powders. The dominant mechanisms of densification were found to be plasticity and creep. Large discrepancies were detected between the data and previous models for these mechanisms. Improved models are presented which, while still approximate, include new physical ideas and give a better description of the experiments. more...
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