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Compressive Strength of EN AC-44200 Based Composite Materials Strengthened with alpha-Al2O3 Particles

Kurzawa A., Kaczmar J. W.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 2

43--48

PL

The paper presents results of compressive strength investigations of EN AC-44200 based aluminum alloy composite materials reinforced with aluminum oxide particles at ambient and at temperatures of 100, 200 and 250oC. They were manufactured by squeeze casting of the porous preforms made of α-Al2O3 particles with liquid aluminium alloy EN AC-44200. The composite materials were reinforced with preforms characterized by the porosities of 90, 80, 70 and 60 vol. %, thus the alumina content in the composite materials was 10, 20, 30 and 40 vol.%. The results of the compressive strength of manufactured materials were presented and basing on the microscopic observations the effect of the volume content of strengthening alumina particles on the cracking mechanisms during compression at indicated temperatures were shown and discussed. The highest compressive strength of 470 MPa at ambient temperature showed composite materials strengthened with 40 vol.% of α-Al2O3 particles.

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Bending Strength of EN AC-44200 – Al2O3 Composites at Elevated Temperatures

Kurzawa A., Kaczmar J. W.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 1

103--108

EN

The paper presents results of bend tests at elevated temperatures of aluminium alloy EN AC-44200 (AlSi12) based composite materials reinforced with aluminium oxide particles. The examined materials were manufactured by squeeze casting. Preforms made of Al2O3 particles, with volumetric fraction 10, 20, 30 and 40 vol.% of particles joined with sodium silicate bridges were used as reinforcement. The preforms were characterised by open porosity ensuring proper infiltration with the EN AC-44200 (AlSi12) liquid alloy. The largest bending strength was found for the materials containing 40 vol.% of reinforcing ceramic particles, tested at ambient temperature. At increased test temperature, bending strength Rg of composites decreased in average by 30 to 50 MPa per 100°C of temperature increase. Temperature increase did not significantly affect cracking of the materials. Cracks propagated mainly along the interfaces particle/matrix, with no effect of the particles falling-out from fracture surfaces. Direction of cracking can be affected by a small number of agglomerations of particles or of non-reacted binder. In the composites, the particles strongly restrict plastic deformation of the alloy, which leads to creation of brittle fractures. At elevated temperatures, however mainly at 200 and 300°C, larger numbers of broken, fragmented particles was observed in the vicinity of cracks. Fragmentation of particles occurred mainly at tensioned side of the bended specimens, in the materials with smaller fraction of Al2O3 reinforcement, i.e. 10 and 20 vol.%.

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Bending Strength of Composite Materials with EN AC-44200 Matrix Reinforced with Al2O3 Particles

Kurzawa J., Kaczmar J. W.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 1 spec.

61--64

EN

There are presented results of a research on bending strength of aluminum alloy EN AC-44200 based composite materials reinforced with aluminum oxide particles. The composite materials were manufactured by squeeze casting with the liquid EN AC-44200 Al alloy of porous ceramic preforms under pressure of 100 MPa. For reinforcing of the EN AC-44200 matrix alloy, preforms made of Al2O3 particles with porosity 60, 70, 80 and 90% were applied. In relation to unreinforced EN AC-44200 base Al alloy, bending strength of composite materials increased about 10% per each 10 vol.% increase of Al2O3 particles in the matrix. The highest bending strength of over 400 MPa was reached by the materials reinforced with 30 and 40 vol.% of Al2O3 particles. Microscopic observations of fracture surfaces confirm that the particles intensively restrict plastic deformation of the alloy, which contributes to creation of a typically brittle fracture. The particles present on the crack propagation path inhibit development of microcracks initiated during bend tests. Most often, the fracture runs through interfacial matrix-particle boundaries, which is caused by brittle bridges of silica binder, present on these boundaries.

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Tribological properties of Cu based composite materials strengthened with Al2O3 particles

Kaczmar J., Granat K., Grodzka E., Kurzawa A.

Archives of Foundry Engineering

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2012

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Vol. 12, iss. 2s

33--36

EN

In the present work copper was strenghtened with 20 and 30 vol. % of alumina particles characterized by diameter of 3-6μm. The copper based composite materials were manufactured by the squeeze casting method. Preheated preforms made from Al2O3 particles were placed in the desired place in the heated cast die and the squeeze casting process with liquid copper was performed applying the infiltration pressure of 90MPa and pressure was kept for 10-15s until solidification was complete. The microstructure and physical properties: Brinell hardness (HBW) and density were characterized. Metallografic examinations showed that alumina particles were uniformly distributed in the copper matrix. Hardness of 208 HBW for composite materials containing 30 vol.% of particles was achieved. Wear investigations were performed applying the tribological pin-on-disc tester. Friction forces between copper based composite materials containing 20 and 30 vol. % of Al2O3 particles and cast iron were registered and wear was determined on the base of the specimen mass loss after 1.0, 3.5 and 8.5 km friction distance.

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Tribological properties of AC44200 based composites strenghead with Al2O3 particles

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

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 2

69-74

EN

The paper presents a research on abrasion resistance of aluminium-based composites consisting of EN AC-44200 matrix reinforced with Al2O3 particles. The examinations revealed that wear intensity of the composites decreased with increasing volume fraction of the particles. Much more intensive abrasive wear was observed on the first kilometre in comparison to the wear on the subsequent distances, i.e. from 1 to 3.5 km and from 3.5 to 8.5 km of the wear distance. Microscopic examinations permitted determining the way and type of wear occurring in the examined materials. In the case of the AC-44200 matrix, typical adhesive wear is observed. In composite materials however, abrasive wear prevails over adhesive wear. Increased volume fraction of Al2O3 particles in composite materials results in increasing friction factor in average by 0.250 per each 10 vol.%. Wear of the cast-iron counterspecimen is also strongly dependent on volume fraction of the reinforcing particles. The counterspecimen demonstrates the largest wear when working in contact with a composite material containing 40 vol.% of Al2O3 particles.