Wyniki wyszukiwania - BazTech

1

Mikrostruktura materiałów kompozytowych na osnowie stopu EN AW-2024 umacnianych cząstkami α-Al2O3

Kurzawa Adam, Kaczmar Jacek W.

Prace Instytutu Odlewnictwa

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2019

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Vol. 59, no. 1

3--13

PL

W pracy zostały przedstawione wyniki badań mikrostruktur materiałów kompozytowych wytwarzanych metodą infiltracji ciśnieniowej preform z cząstek ceramicznych α-Al2O3 stopem aluminium EN AW-2024. W badaniach mikroskopowych w szczególności oceniano jakość połączeń na granicach międzyfazowych osnowa-cząstki ceramiczne. Stwierdzono, że krzemionka (SiO2) stosowana do łączenia cząstek tlenku glinu w preformie powoduje wzbogacenie osnowy w krzem (Si), w części dyfundujący do stopu aluminium, który jednak pozostaje w osnowie w postaci skupisk SiO2, szczególnie w obrębie cząstek ceramicznych o dużym stopniu aglomeracji. Infiltracja porów otwartych preformy ceramicznej stopem EN AW-2024 o ograniczonej rzadkopłynności utrudnia proces infiltracji, pozostawiając lokalnie występującą porowatość. Propagacja pęknięć w materiale kompozytowym po badaniach właściwości mechanicznych następuje głównie po granicach międzyfazowych osnowa- -cząstka, szczególnie w miejscach o zwiększonej ilości rezydualnej krzemionki (SiO2) w osnowie. Na powierzchniach przełomów obserwuje się cząstki ceramiczne umocnienia α-Al2O3 o mocnym adhezyjnym połączeniu z osnową, które podczas tworzenia złomu ulegają pęknięciom.

EN

The paper presents the results of investigations into the microstructures of composite materials produced by pressure infiltration of preforms of ceramic α-Al2O3 particles with aluminium alloy EN AW-2024. In particular, the quality of the bonds at the interphase boundaries of matrix-ceramic particles was evaluated using microscopy investigations. It was found that silica (SiO2) used for bonding alumina particles in the preform causes an enrichment of the matrix in silicon (Si), which partly diffuses to aluminium alloy, yet remains in the matrix in the form of SiO2 concentrations, especially within ceramic particles with a high degree of agglomeration. The infiltration of open pores of ceramic preforms with EN AW-2024 alloy of limited flowing power hinders the infiltration process, resulting in local porosity. The propagation of cracks in the composite material after tests for mechanical properties occurs mainly along the interphase boundaries of the matrix-particle, especially in places with an increased residual amount of silica (SiO2) in the matrix. On the surfaces of the fractures ceramic particles of the α-Al2O3 reinforcement are observed, they form a strong adhesive bond with the matrix and crack during the formation of scrap metal.

2

Manufacturing of ceramic porous preforms by sintering of Al2O3 powder

Kremzer M., Dobrzański L. A., Dziekońska M., Macek M.

Archives of Materials Science and Engineering

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2015

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Vol. 75, nr 2

63--69

EN

Purpose: The aim of the study is to develop a method of manufacturing porous preforms based on ceramic powder Al2O3 used as the strengthening for the production of modern metal composite materials. Design/methodology/approach: Semi-products were produced by sintering of ceramic powders with addition of the pores forming agent. The material of the preform was Al2O3 powder while as a pores and canals forming agent inside the sintered ceramic skeleton coal and charcoal were used. Particle size measurements of Al2O3 powder, charcoal, and coal using laser particle size measurer were made. Preforms were also observed in the scanning electron microscopy (SEM). Findings: The obtained preforms have a volume fraction of ceramic phase in the range of 20-44% due to the differences of sintering temperature and various portion and coal origin used as pores forming agent. Research limitations/implications: The main limitation of presented method is the possibility of obtaining preforms where a porosity are not exceeding 80%. Where, in the case of using ceramic fibers, the pores may be more than 90% volume fraction of the material. Practical implications: Manufactured ceramic preforms are widely used as a reinforcement for production of composite materials by infiltration methods. This method enables the production of metal and locally reinforced composite products with an exact mapping shape. Originality/value: Results indicate the possibility of obtaining new preforms which are a cheaper alternative to semi-finished products based on ceramic fibers. On the other hand, the use of coal and charcoal as a pores forming agent is an economically justified alternative to previously used materials such as fibers carbon and graphite.

3

Application of ceramic preforms to the manufacturing of ceramic-metal composites

Jach K., Pietrzak K., Wajler A., Sidorowicz A., Brykała U.

Archives of Metallurgy and Materials

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2013

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Vol. 58, iss. 4

1425--1428

EN

This paper presents new solution to manufacturing Cu-Al2O3 composites with a dispersed reinforcement phase. It consists in substituting commonly used commercial alumina powder with crushed ceramic foam. Very low strength of thin-walled Al2O3 porous foams results in both their easy destruction and isolation of fragments <200 μm. The addition of the ceramic phase is 3-10 vol.%. The sintering process is performed for 30 min in a hot-press at 1050°C and 30 MPa. The aim of the presented paper is to study the effect of the volume content of the ceramic phase on the microstructure and selected physical and thermal properties of copper - alumina composites.

PL

Artykuł przedstawia nowatorskie rozwiązanie wytwarzania kompozytów Cu-Al2O3 z rozproszoną fazą wzmacniającą. Polega ono na wykorzystaniu zamiast powszechnie stosowanego handlowego proszku tlenku glinu, rozkruszonej pianki cera- micznej. Wysoka kruchość cienkościennych, porowatych pianek Cu-Al2O3 pozwoliła na łatwe ich rozdrobnienie i wyodrębnienie frakcji o fragmentach wielkości < 200 /im. Dodatek fazy ceramicznej wynosił 3-10%obj. Proces spiekania prowadzono w temperaturze 1050°C w czasie 30 min i pod ciśnieniem 30 MPa. Celem pracy było określenie wpływu ilości dodatku fazy ceramicznej na mikrostrukturę oraz wybrane właściwości otrzymanych kompozytów.

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Wpływ rodzaju spoiwa na właściwości reologiczne zawiesin zastosowanych do otrzymywania ceramicznych tworzyw porowatych

Jach K., Tomaszewski H., Węglarz H.

Materiały Ceramiczne

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2012

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T. 64, nr 4

536-540

PL

W niniejszej pracy tworzywa ceramiczne o kontrolowanej porowatości przygotowano metodą polegającą na osadzaniu na tworzywie polimerowym proszku ceramicznego z masy lejnej (ang. polymeric sponge method). Jako podłoża wykorzystano gąbki poliuretanowe firmy Kureta. Ceramiczne materiały porowate otrzymano na bazie tlenku glinu (α-Al2O3, Almatis). Wodne zawiesiny tlenkowe przygotowano z wykorzystaniem dwóch rodzajów spoiwa: poli(alkoholu winylowego) oraz dyspersji polimeru na bazie estru kwasu akrylowego i styrenu. W pracy przedstawiono wyniki badań reologicznych sporządzonych mas lejnych oraz mikrostrukturę otrzymanych tworzyw ceramicznych.

EN

In the present study, porous ceramic materials were prepared by the polymeric sponge method. Polyurethane sponge (Kureta) was used as a substrate. Porous ceramic materials were obtained on the basis of aluminium oxide (α-Al2O3, Almatis), aqueous suspensions prepared with binders of two types: polyvinyl alcohol and a dispersion based on methacrylic acid esters and styrene. The paper presents the results of studies on the rheological properties of the ceramic slurries and the results of strength tests of the resultant ceramic materials.

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Structure and properties of porous ceramic preforms made of α-alumina particles

Kaczmar J. W., Kurzawa A.

Archives of Foundry Engineering

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2010

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Vol. 10, iss. 1 spec.

157--162

EN

Properties of ceramic preforms made of α-alumina particles for strengthening of metal based composite materials manufactured by squeeze casting are discussed in the paper. Composite materials strengthened with ceramic particles can be then plastically worked in order to remove the residual porosity and give the final net shape. There was investigated the permeability of porous preforms as the measure of the open porosity making possible the infiltration process with the molten metal, compression strength, bending strength and shear strength determining the stability of porous ceramic preforms during infiltration. Performed investigations allow to ascertain the occurrence of the open porosity in the porous preforms and strong effect of porosity on permeability. The largest permeability of 19 m2/Pa•s showed porous preforms characterized by porosity the of 90%. The strength properties increased with the decrease of preforms porosity and the prerforms characterized by 60% of porosity were characterized by the largest strength properties (bending strength Rg =7 MPa, compression strength Rc = 11.5 MPa, shear strength Rt = 4.0 MPa). The microscopic observations of fractures surfaces allow to evaluate quality and forming phenomena of the binder bridges connecting the ceramic particles.

6

Aluminium matrix composites fabricated by infiltration method

Dobrzański L. A., Kremzer M., Nowak A., Nagel A.

Archives of Materials Science and Engineering

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2009

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Vol. 36, nr 1

5-11

EN

Purpose: The aim of this work is to examine the structure and properties of metal matrix composites obtained by infiltration method of porous ceramic preforms by liquid aluminium alloy. Design/methodology/approach: Ceramic preforms were manufactured by the sintering method of ceramic powder. The preform material consists of powder Condea Al2O3 CL 2500, however, as the pore forming the carbon fibers Sigrafil C10 M250 UNS were used. Then ceramic preforms were infiltrated with liquid eutectic EN AC - AlSi12 aluminum alloy. Stereological and structure investigations of obtained composite materials were made on light microscope. The mechanical properties of obtained composite material were investigated in tensile strength test and hardness test. Findings: It was proved that developed technology of manufacturing of composite materials based on the porous ceramic Al2O3 preforms infiltrated by liquid aluminium alloy ensures expected structure and strength Hardness increased about twice compared to the matrix and this process can be used in practice. Practical implications: The presented metal matrix composites fabrication technology allows to obtain locally reinforced elements and near net shape products. Originality/value: Results show the possibility of obtaining the new aluminium matrix composite materials being the cheaper alternative for other materials based on the ceramic fibers.

7

The structure and properties of hybrid preforms for composites

Naplocha K., Granat K.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 22, nr 2

35-38

EN

Purpose: Article describes production technology of hybrid preform for reinforcing of composite materials. Some important properties such as shear strength and permeability were investigated in order to evaluate the usability of the preform for squeeze casting process. Design/methodology/approach: The preforms produced by mixing of alumina "Saffil" fibers with graphite in form of flakes or fibers have open porosity. An inorganic binder used for production of preform ensures sufficient strength needed during high pressure infiltration process. The investigations of the structure of ceramic hybrid preforms on the scanning electron microscope (SEM) have been made. Findings: The produced preforms in spite of worse permeability reveals open porosity and are suitable for infiltration process. Graphite with alumina fibers forms skeletal structure and can be easily incorporated into alumina matrix. Research limitations/implications: Proposed method can be used for manufacturing of hybrid preforms with graphite fibers less than 10 vol. % due to its nonwettable by inorganic binders. Practical implications: Obtained preform can be widely used as the rinforcement to produce hybrid composite materials by the infiltration method. Aluminium casting alloys can be locally reinforced to improve mainly strength at high temperature and wear resistance. Originality/value: Article is valuable for persons, that are interesting in production of casting composite materials reinforced with ceramic preform. Proposed method allows incorporate graphite into preform with about 6,5 to 15,0% of Al2O3 fibers (Saffil).

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Composite materials based on porous ceramic preform infiltrated by aluminium alloy

Dobrzański L. A., Kremzer M., Nowak A. J., Nagel A.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 20, nr 1-2

95-98

EN

Purpose: The goal of this project is the optimization of manufacturing technology of the ceramic preforms based on Al2O3 powder manufactured by the pressure infiltration method with liquid metal alloy. Design/methodology/approach: Ceramic preforms were manufactured by the method of sintering of ceramic powder. The preform material consists of powder Condea Al2O3 CL 2500, however, as the forming factor of the structure of canals and pores inside the ceramic agglomerated framework the carbon fibers Sigrafil C10 M250 UNS were used. Then ceramic preforms were infiltrated with liquid EN AC - AlSi12 aluminium alloy. Stereological and structure investigations of obtained composite materials were made on light microscope. Findings: It was proved that developed technology of manufacturing of composite materials with pore ceramic Al2O3 infiltration ensures expected structure and can be used in practice. Practical implications: The developed technology allows to obtain method's elements locally reinforced and composite materials with precise shape mapping. Originality/value: The received results show the possibility to obtaining the new composite materials being the cheaper alternative for other materials based on the ceramic fibers.

9

Application of pressure infiltration to the manufacturing of aluminium matrix composite materials with different reinforcement shape

Dobrzański L. A., Kremzer M., Nagel A.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 24, nr 2

183-186

EN

Purpose: The purpose of this work is to investigate the influence of reinforcing phase's shape on structure and properties of composite materials with aluminium alloy matrix. Design/methodology /approach: The material for studies was produced by a method of pressure infiltration of the porous ceramic framework. In order to investigate the influence of reinforcing phase's shape the comparison was made between the properties of the composite material based on preforms obtained by Al203 Alcoa CL 2500 powder sintered with addition of pore forming agent in form of carbon fibres Sigrafil C 10 M250 UNS from Carbon Group company and composite materials based on much more expensive commercial fibrous preforms. The matrix consisted of cast aluminium alloy EN AC — AlSi12. The observations of the structure were made on the light microscope and in the scanning electron microscope. The strength properties were established on the basis of static tensile tests. Findings: The composite materials, obtained on the basis of ceramic preforms consisted of Al203 particles, are showing better strength properties in comparison to materials obtained by the fibrous preform infiltration. Practical implications: The composite materials made by the developed method can find application as the elements of devices where beside the benefits from utilizable properties the small weight is required (mainly in aircraft and motorization industries). Originality/value: The obtained results show the possibility of manufacturing the composite materials by the method of porous sintered framework pressure infiltration based on the ceramic particles, characterized with the better properties than similar composites reinforced with fibres.

10

Fabrication of ceramic preforms based on Al2O3 CL 2500 powder

Dobrzański L. A., Kremzer M., Nagel A., Huchler B.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 18, nr 1-2

71--74

EN

Purpose: The aim of a work is to elaborate the method of manufacturing the porous, ceramic preforms based on Al2O3 particles used as the reinforcement in order to produce modern metal matrix composite materials. Design/methodology/approach: Semi-finished products were manufactured by the method of sintering of ceramic powder. The preform material consists of powder Condea Al2O3 Cl 2500, however, as the forming factor of the structure of canals and pores inside the ceramic, agglomerated framework the carbon fibres Sigrafil C10 M250 UNS were used. The investigations of the structure of powder Al2O3 Condea Cl 2500, the used carbon fibres and the obtained ceramic preforms on the scanning electron microscope (SEM) have been made. The measurement of permeability of the obtained materials on the specially designed station has also been made. Findings: The obtained preforms are characterised by volumetric participation of ceramic phase of 15 - 31%, what is the result of differential addition of the pores forming factor, and the high permeability indicates on “the open porosity”. Research limitations/implications: The basic limit of the mentioned method is the possibility of obtaining preforms of porosity less than 85%, where in case of using the ceramic fibres the pores can be more than 90% of material volumetric. Practical implications: The manufactured ceramic preforms are widely used as the reinforcement to produce the composite materials by the method of infiltration. That method allows manufacturing the metal elements locally reinforced and the near-net shape composite products. Originality/value: The received results show the possibility of obtaining the new preforms being the cheaper alternative for semi-finished products based on the ceramic fibres and the use of carbon fibres as the pores forming agent indicate that it is the high-quality process.