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1

The Influence of Graphite Type on the Abrasive Wear of AlMg10 Matrix Composites

Łągiewka M., Konopka Z., Zyska A., Nadolski M.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 1 spec.

65--68

EN

The presented work discuss the influence of various types of graphite additions on the abrasive wear of AlMg10 matrix alloy composites. Flake graphite, electrographite, and short graphite fibre were used as a composite reinforcement. Composites containing 10 vol. % of graphite particles were produced by mechanical mixing of the liquid alloy with simultaneous introduction of the reinforcement. Composite suspensions were gravity cast into metal moulds. The achieved castings were tested for the abrasive wear. Also the pure matrix alloy was examined. Microphotographs of the produced materials were taken, the specimens were also examined after the abrasion test by observing the microsections perpendicular to the abraded surface. The carried out experiments allow to state that even the little addition of graphite influences beneficially the tribological properties of composite under small loads applied to the frictional pair. It was found that under the increased load (30 N) the least abrasive wear is exhibited by the composite reinforced with graphite fibre, the largest one occurring for the composite reinforced with electrographite. The composite reinforced with electrographite, however, exhibited the mass loss less by 25% than the pure matrix alloy.

2

The solidification during flow of composite suspension in the permanent mould

Łągiewka M., Konopka Z., Zyska A., Nadolski M.

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 2

75-78

EN

The presented work presents the influence of graphite particles on the solidification kinetics of metal suspension based on AlSi10Mg alloy during the die cavity filling. In order to examine this problem, the measurements concerning temperature changes in the selected points of the metal mould have been taken for two materials poured into the die: the pure AlSi10Mg alloy and the alloy reinforced with graphite particles. Thus the solidification and cooling curves of the examined material have been achieved. The recorded temperature changes have served as a basis for preparing graphs representing the velocity of the metal stream and the distance travelled by the front of the stream against the time. The introduction of graphite particles into the matrix alloy has caused the shortening of the distance flown by the material by 50% as compared with the non-reinforced alloy. The recorded temperature changes have allowed also for determining the temperature changes for the front of the metal stream during the die filling. Taking into account these results it has been found that the AlSi10Mg+10%Cgr composite begins its solidification after having covered the distance seven times shorter than the corresponding distance measured for the non-reinforced AlSi10Mg alloy.

3

Microstructure of hypereutectic Fe-C-V alloys

Kawalec M.

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 2

55-60

EN

The study shows the results of examinations of the microstructure of the in-volume-solidifying Fe-C-V alloys containing carbon in a range of 1.53-3.09% and vanadium in a range of 14.73-15.71%. All the examined alloys were hypereutectic alloys as proved by the cooling curves, relevant calculations (Sc) and examinations under the microscope. It has been confirmed that the primary carbides of vanadium are crystallising in the form of non-faceted dendrites, acting as a substrate for the growing fibres of vanadium eutectic. The content of primary carbides in the microstructure depends on the content of carbon and vanadium in the alloy. During the conducted research an attempt was also made to determine the content of primary and eutectic carbides and to establish a relationship between carbon and vanadium content in the alloy and the content of primary carbides. In Fe-C-V alloys, besides primary carbides, also a fibrous eutectic composed of ferrite and vanadium carbides of the VC1-x type crystallises. To conduct the previously planned examinations, a series of melts with a variable carbon and vanadium content was carried out under argon atmosphere in a Balzers vacuum furnace. Specimens were examined under an optical microscope, but to investigate in more detail the geometry of individual phases, they were deep etched with aqua regia and examined by scanning electron microscopy. In the investigated alloys, the chemical composition of the crystallised phases was determined by EDS microanalysis.

PL

W pracy przedstawiono wyniki badań mikrostruktury stopów Fe-C-V, o zawartości węgla w zakresie 1.53-3.09% i wanadu w zakresie 14.73-15.71%, krystalizujących w sposób objętościowy. Wszystkie badane stopy są stopami nadeutektycznymi, co potwierdziły krzywe stygnięcia, odpowiednie obliczenia (Sc) oraz obserwacje mikroskopowe. Potwierdzono, że pierwotne węgliki wanadu krystalizują w postaci dendrytów nieścianowych, na których wzrastają włókna eutektyki wanadowej. Udział węglików pierwotnych w mikrostrukturze jest zależny od zawartości węgla i wanadu w stopie. W pracy określono także udział węglików pierwotnych i eutektycznych oraz wyznaczono zależność pomiędzy zawartością węgla i wanadu w stopie a udziałem węglików pierwotnych. Oprócz węglików pierwotnych w stopach Fe-C-V krystalizuje eutektyka włóknista składająca się z ferrytu i węglików wanadu typu VC1-x. W celu wykonania założonych badań przeprowadzono serię wytopów o zmiennej zawartości węgla i wanadu w piecu próżniowym typu Balzers w atmosferze argonu. Próbki obserwowano za pomocą mikroskopu optycznego, a w celu bardziej szczegółowego zbadania geometrii poszczególnych faz trawiono je głęboko wodą królewską i obserwowano za pomocą mikroskopu skaningowego. W badanych stopach przeprowadzono również pomiary składu chemicznego wykrystalizowanych faz metodą punktowej mikroanalizy EDS.

4

Heterofazowa struktura tłoków kompozytowych wytwarzanych metodą odlewania kokilowego

Dolata-Grosz A., Dyzia M., Lech-Grega M.

Rudy i Metale Nieżelazne

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2010

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R. 55, nr 9

614-618

PL

Wielofazowe umocnienie stopów aluminium stanowi nowe rozwiązanie materiałowe pozwalające w znacznym stopniu na rozszerzenie możliwości projektowania i zróżnicowania właściwości wyrobów, przede wszystkim mechanicznych i tribologicznych. Tego typu kompozyty wykorzystano do produkcji tulei cylindrowych w silnikach Hondy Prelude 2.3 L i Toyoty Celica. Zastosowanie preformy z udziałem 12 % włókien Al2O3 i 9 % włókien węglowych pozwoliło na obniżenie masy bloku silnika, poprawę warunków chłodzenia oraz zmniejszenie zużycia poprzez tarcie. Nowym rozwiązaniem materiałowo--technologicznym może okazać się wykorzystanie metody zawiesinowej do wytwarzania kompozytów o zbrojeniu heterofazowym. Jak wykazały badania autorów, zastosowanie zbrojenia w postaci mieszaniny cząstek węglika krzemu i węgla szklistego pozwala na stabilizację współczynnika tarcia, a przede wszystkim obniżenie zużycia partnera tarcia. Właściwości te mogą być wykorzystane w układzie tribologicznym tłok-cylinder, od którego wymaga się stabilności wymiarowej, wytrzymałości i trwałości. Z kolei właściwości kompozytów odlewanych determinowane są strukturą, czyli rodzajem, wielkością, kształtem i udziałem umocnienia oraz składem fazowym osnowy. Istotna jest również stabilność powierzchni międzyfazowej, która zapewnia trwałość wyrobu kompozytowego. W artykule przedstawiono strukturę i stan powierzchni rozdziału faz w heterofazowych tłokach kompozytowych odlewanych kokilowo. W badaniach wykorzystano metody mikroskopii świetlnej i skaningowej.

EN

The multi-reinforcement of aluminium alloys is a new material solution permitting in considerable degree on development of possibility design and properties diversification of product, first of all mechanical and tribological properties. Such kind of composites used as the production of cylinder sleeves in Honda Prelude 2.3 L and Toyota Celica engines. Application of 12 % Al2O3 short fibres and 9 % carbon preform permitted on lowering the mass of block of engine, improvement of conditions of cooling as well as decrease friction wear. New material and technological solution could be stirring method for obtaining heterophase composite suspension. How the authors' investigations showed, applying of silicon carbide and glassy carbon mixture of particles as reinforcement make possible to obtain material with stable of the friction coefficient and the first of all lowering wear of friction partner. These properties can be used in piston-cylinder tribological system which was required dimension stability, strength and durability. The properties of cast composites determined by the structure i.e. kind, size, shape and volume of reinforcement as well as the phase composition of the matrix. It essential is also the stability of the interface which assures the stability of composite product. The structure and the state of interface in composite pistons with heterophase reinforcement obtained by mould casting method are presented in the article. In the investigations the method of light and scanning microscopy was used.

5

Die-cast heterophase composites with AlSi13Mg1CuNi matrix

Dyzia M., Dolata-Grosz A., Wieczorek J., Śleziona J.

Archives of Foundry Engineering

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2010

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Vol. 10, iss. 1 spec.

301--304

EN

On the basis of the performed tests, an advantageous interaction of glassy carbon particles in a couple consisting of a heterophase composite and a spheroidal cast iron has been corroborated. It was found that, the presence of glassy carbon in the heterophase composite (SiC+C) affects the stabilization of the friction coefficient value as a function of the friction distance and reduces the intensity of the wearing-in stage of the interacting surfaces. Both a decrease of the friction coefficient and the wear of the heterophase composites may be connected with the carbon particles' chipping effect and the deposition of its fragments on the surface of the interacting components of the friction couple, which forms a kind of a solid lubricating agent in the system. This should allow applying of this material to the composite piston-cylinder sleeve system in piston air-compressors. Further works will concern the selection of the matrix alloy composition with the purpose of reducing the phenomenon of particles chipping during machining. It seems that one of the possibilities is the application of a more plastic matrix and optimizing the fraction of reinforcing phases and their gradient distribution in the casting.

6

The phenomena occurring along borderline of the phase shares in the casted Al-Al2O3 composites

Garbala K., Patejuk A.

Archives of Foundry Engineering

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2009

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Vol. 9, iss. 2

73-76

EN

In the foregoing work, one analyses in detail the use of nickel cover on the Al2O3 particles in composites with the Al matrix (Al alloy). The mechanisms of developing the Al-Ni combination on the interface were the subject of the detailed analysis. The aim of the work was to present the model research, the aim of which is to describe mechanism of the combination in the sphere of aluminum-nickel sphere, in gradient. The research of the combination between the above mentioned metals was conducted in gradient of the heating temperature lower than the melting temperature of aluminum and in the time of parch. One observed visible changes in the structure and chemical composition on the butt of those metals, caused by the concentration diffusion mechanisms. Moreover, in the temperature of 640oC in the time of 48 hours, one observed the Frenkel pores.

7

Selected mechanical properties of aluminum composite materials reinforced with SiC particles

Kurzawa A., Kaczmar J. W., Janus A.

Archives of Foundry Engineering

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2008

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Vol. 8, iss. 2

99-102

EN

This work presents the results of research concerning influence of ceramic particles' content of silicon carbide on selected mechanical properties of type AW-AlCu4Mg2Mn - SiC composite materials. Composites produced of SiC particles with pressure infiltration method of porous preform and subject to hot plastic forming in the form of open die forging were investigated. The experimental samples contained from 5% up to 45% of reinforcing SiC particles of 8÷10žm diameter. Studies of strength properties demonstrated that the best results, in case of tensile strength as well as offset yield strength, might be obtained while applying reinforcement in the amount of 20-25% vol. of SiC. Application of higher than 25% vol. contents of reinforcing particles leads to gradual strength loss. The investigated composites were characterized by very high functional properties, such as hardness and abrasive wear resistance, whose values increase strongly with the increase of reinforcement amount. The presented results of the experiments shall allow for a more precise component selection of composite materials at the stage of planning and design of their properties.

8

The influence of graphite particles on supercooling of composite suspension

Łągiewka M., Konopka Z., Zyska A.

Archives of Foundry Engineering

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2007

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Vol. 7, iss. 2

139-142

EN

The work presents the solidification kinetics of a composite suspension with graphite particles dispersed in AlMg10 alloy matrix during its flow along a runner. The temperature field for investigated materials has been determined by measuring the suspension temperature values during flow and solidification in the elongated runner-like mould cavity. The influence of the quantity of ceramic particles on the temperature of the solidification beginning has been shown, and by the same its influence on the supercooling of the flowing composite suspension. Differences between the supercooling values for matrix alloy and for composites have been revealed. The obtained results have been interpreted pointing to the influence of graphite particles on activating the nucleation and change of the heat exchange conditions between the flowing suspension and the mould wall.

9

Czynniki determinujące kształtowanie struktury w kompozytach Al-cząstki ceramiczne w procesie odlewania odśrodkowego

Dolata-Grosz A., Śleziona J.

Inżynieria Materiałowa

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2003

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R. XXIV, nr 6

613-616

PL

W pracy przedstawiono problem dotyczący odlewania zawiesiny kompozytowej do formy wirującej, w układzie z poziomą osią obrotu. Wyniki badań wykazały, że na segregację cząstek ceramicznych w odlewie, oprócz gęstości komponentów i stosowanej prędkości obrotowej formy, nakłada się wpływ wielu dodatkowych zjawisk i procesów m.in. ciśnienia i warunków cieplnych, które determinują proces krzepnięcia odlewu. Wpływ tych czynników, zarówno technologicznych jak i fizyczno-chemicznych, kształtuje strukturę kompozytu, a tym samym rozmieszczenie cząstek ceramicznych w osnowie. Poznanie zjawisk i procesów umożliwiających sterowanie strukturą i rozmieszczeniem zbrojenia - w procesie odlewania odśrodkowego - może wkrótce stać się optymalną i ekonomiczną drogą w produkcji metalowych kompozytów warstwowych na skalę przemysłową.

EN

In this work, the problem of casting composites suspension by the centrifugal process with level rotational axis has been presented. In this method the structure and ceramic particles segregation depend on many factors, such as: rotational speed centrifugal form, difference in density between the molten metal and ceramic particles, their volume fraction and reinforcement granulation as well as viscosity and crystallization conditions. Influences of this factors, technological as well as physical and chemical, shapes composite structure and distribution of ceramic particles in alloy. Knowledge of phenomena's and process, to which make possible to control of composite structure and reinforcement distribution in the centrifugal casting process, may soon become optimal economical way of producing metal matrix composite layers in an industrial scale.

10

Wpływ modyfikacji powierzchniowej cząstek na strukturę kompozytów odlewanych AlMg4-(Al-Al2O3)p.

Olszówka-Myalska A., Śleziona J., Formanek B., Myalski J.

Inżynieria Materiałowa

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2000

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R. XXI, nr 6

379-382

PL

Określono wpływ obróbki powierzchniowej zbrojenia, jako elementu technologii wytwarzania kompozytu, na rozmieszczenie cząstek Al-Al2O3 w stopie AlMg4 oraz strukturę połączenia cząstki kompozytowe-stop. Odlewany materiał kompozytowy wytworzono wprowadzając do ciekłego stopu AlMg4 cząstki kompozytowe Al-Al2O3 otrzymane metodą MA przy użyciu młyna rotacyjno-wibracyjnego. Zastosowano cząstki kompozytowe bez dodatkowej modyfikacji powierzchniowej oraz modyfikowane dwoma sposobami - przy pomocy NaOH oraz związkami boru. W zależności od warunków mieszania, temperatury odlewania i innych parametrów procesu otrzymano równomierne lub zróżnicowane rozmieszczenie proszku kompozytowego w odlewie. W odróżnieniu od klasycznych zawiesin stop Al - cząstki Al2O3 stwierdzono, że można wprowadzać proszek kompozytowy (Al-Al2O3)p do ciekłego AlMg4 bez powierzchniowej modyfikacji, a modyfikacja NaOH oraz modyfikacja związkami boru powodowała powstanie połączenia cząstki - AlMg4 o niekorzystnej strukturze.

EN

The influence of surface treatment of composite powder on distribution of composite powder (Al-Al2O3)p in AlMg4 matrix and bonding between composite powder and AlMg4 alloy was analysed. Composite casts were produced by stirring of molten AlMg4 alloy and (Al-Al2O3)p composite powder obtained in vibration-rotary mill (MA method). Composite powders without any surface modification and with two kinds of preparation in NaOH and in boron compounds were used. In dependence on stirring conditions, casting temperature and other technological parameters uniform or gradient distribution of composite powder was observed. In the difference from classical molten aluminium - Al2O3 particles mixture it has been found that it is possible to introduce (Al-Al2O3)p composite powders into liquid AlMg4 without their surface modification and the modification with NaOH and boron compounds caused the composite particle - AlMg4 interface with disadvantageous structure.