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Bending strength and fracture investigations of Cu based composite materials strengthened with \delta-alumina fibres

Kaczmar J. W., Granat K., Naplocha K., Kurzawa A., Grodzka E., Samociuk B.

Archives of Foundry Engineering

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2013

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Vol. 13, iss. 2

59--63

EN

Bending strength, thermal and electric conductivity and microstructure examinations of Cu based composite materials reinforced with Saffil alumina fibres are presented. Materials were produced by squeeze casting method applying the designed device and specially elaborated production parameters. Applying infiltration pressure of 90MPa and suitable temperature parameters provided manufacturing of copper based composite materials strengthened with Saffil alumina fibres characterized by the low rest porosity and good fibre-matrix interface. Three point bending tests at temperatures of 25, 100 and 300ºC were performed on specimens reinforced with 10, 15 and 20% of Saffil fibres. Introduced reinforcement effected on the relatively high bending strengths at elevated temperatures. In relation to unreinforced Cu casting strength of composite material Cu – 15vol.% Saffil fibres increase by about 25%, whereas at the highest applied test temperature of 300ºC the improvement was almost 100%. Fibres by strengthening of the copper matrix and by transferring loads from the matrix reduce its plastic deformation and hinder the micro-crack developed during bending tests. Decreasing of thermal and electrical conductivity of Cu after incorporating fibres in the matrix are relatively small and these properties can be acceptable for electric and thermal applications.

2

Wear behaviour of composite materials based on 2024 Al-alloy reinforced with delta alumina fibres

Kaczmar J. W., Naplocha K.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 43, nr 1

88-93

EN

Purpose: Wear improvement of aluminum matrix composite materials reinforced with alumina fibres, was investigated. The effects of the applied pressure and T6 heat treatment on wear resistance were determined. Design/methodology/approach: Wear tests were carried out on pin-on disc device at constant sliding velocity and under three pressures, which in relation to diameter of specimens corresponds to pressures of 0.8 MPa, 1.2 MPa and 1.5 MPa. To produce composite materials porous performs were prepared. They are characterized by the suitable permeability and good strength required to resist stresses arising during squeeze casting process. Performs exhibited semi-oriented arrangement of fibres and open porosity enabled producing of composite materials 10% (in vol.%) of Al2O3 fibres (Saffil). Findings: In comparison with T6 heat treated monolithic 2024 aluminium alloy composites revealed slightly better resistance under lower pressure. Probably, during wear process produced hard debris containing fragments of alumina fibres are transferred between surfaces and strongly abrade specimens. Under smaller pressures wear process proceeded slowly and mechanically mixed layer MML was formed. Research limitations/implications: Reinforcing of 2024 aluminium alloy could be inefficient for wear purposes. Remelting and casting of wrought alloy could deteriorate its properties. Interdendrite porosities and coarsening of grains even after squeeze casting process were observed. Practical implications: Aluminum casting alloys can be locally reinforced to improve hardness and wear resistance under small pressures. Originality/value: Investigations are valuable for persons, what are interested in aluminum cast composite materials reinforced with ceramic fibre performs.

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Manufacturing and microstructure of MMC based on CuZn38Al2Mn1Fe brass strengthened with δ-alumina fibres

Kaczmar J. W., Granat K., Pietrzak K., Naplocha K., Grodzka E.

Archives of Foundry Engineering

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2010

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Vol. 10, iss. 1 spec.

411--414

EN

Metal matrix composite materials were manufactured by squeeze casting with CuZn38Al2Mn1Fe brass of porous preforms made of δ-alumina SAFFIL fibres. The microstructure, Brinell hardness and Vickers microhardness of manufactured composite materials were characterized. Preforms with 10 and 20 vol. % of fibres were preheated and infiltrated applying the pressure of 80 MPa. Microscopic observations showed that alumina fibres are uniformly distributed in the MA58 matrix and there was not observed the destroying of ceramic fibres during squeeze casting process. Hardness of composite materials strengthened with 20 vol.% of SAFFIL fibres reached 265 HB. At the boundary of composite material/not strengthened MA58 alloy it was ascertained the filtration and retention of iron compound precipitates caused by the small dimensions of pores in the ceramic preform. The collection of iron phase precipitates at the boundary composite material/ not strengthened MA58 alloy effected in the increase of microhardness in this zone to 352 HV. On the base of SEM observations the conclusion on limited wettability of fibres by liquid MA58 brass was drawn.