Formation of the operation surface layer in aluminium matrix composites during friction
Dionizy Biało Politechnika Warszawska, Wydział Mechatroniki, Instytut Inżynierii Precyzyjnej i Biomedycznej, ul. św. A. Boboli 8, 02-525 Warszawa
Annals 3 No. 6, 2003 pages 84-87
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abstract In this work the results of experimental study on formation of the operation surface layer in aluminium matrix composites during friction have been presented. Composites manufactured by powder metallurgy route contain: Al + 4.5 Cu + 0.7 Si + + 0.5 Mg matrix and reinforcing phase - Al2O3 particle with 10% volume fraction. Average size of reinforcing phase was 3, 9, 23 and 53 μm. Tribological experiments were carried out on the pin-on-disk apparatus at dry friction condition with the steel counterspecimen at the following parameters: contact pressure of 0.5÷5 MPa, friction velocity of 1 m/s, friction distance of 6000 m. It was noticed that surface layer undergo to plastic deformation, and has texturing, reducing grain structure (Figs. 1, 2). Operation surface layer hardness nearby the friction surface is higher then hardness of the not deformed material (the core) (Fig. 3). Thickness of the surface layer is the higher, the higher was contact pressure during friction tests and more ductile the material was (Fig. 4). The greatest thickness of the operation surface layer occuring for the matrix material. For the composite materials the dependence between surface layer thickness and granularity of the reinforcing phase was observed. Thickness of this layer was the smaller, the larger was the size of alumina particle. Key words: surface layer, aluminium matrix, friction, powder metallurgy