The wear resistivity evaluation of composite break rotors
Andrzej Wojciechowski*, Jerzy Sobczak**, Zbigniew Bojar***, Krystyna Pietrzak* *Instytut Transportu Samochodowego, ul. Jagiellońska 80, 03-301 Warszawa **Instytut Odlewnictwa, ul. Zakopiańska 73, 30-418 Kraków, ***Wojskowa Akademia Techniczna, ul. Kaliskiego 2, 00-908 Warszawa
Annals 2 No. 4, 2002 pages 223-228
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abstract Particulates reinforced aluminum matrix composites (AIMCs) are generally used on frictional couples working under technically dry friction conditions. Variety of research methodology and lack of commonly used standards concerning estimation of wear resistance contributed to the fact that this paper presents two techniques of tribology testing, according to the authors, the real effects occurring in the frictional couple: break rotor-friction lining in service conditions. The comparative tribology investigations of the different aluminum based composite materials (such as F3S.20S - AlSi9Mr/22 vol.% SiC, F3N.20S - AlSi10FeMnMg/22 vol.% SiC and AlSi12CuNiMg/9 vol.% fly ash precipitator obtained by gravity casting in permanent mold (GR), lost foam method (LF) and squeeze cast (SQ), in as cast and heat treated conditions), which could be used for break rotors and cast iron, have been estimated through defining the tribology wear indexes (friction coefficient and wear resistance) in two independent tests. The obtained findings show that in the given experimental conditions both the irons as well as composites are characterized by similar wear resistance (Tables 1 and 2). The wear of AIMCs depends mostly on the temperature of the active frictional couple. Furthermore, as a result of the research it can be synonymously inferred that the aluminum composites can safely work in the temperature up to 300oC (Figs 3 and 4). The value of the friction coefficient in the frictional couple is equal and stable for all temperatures at which the active friction couple has been examined. All tested materials have fulfilled the requirements concerning the acceptable quantities of friction factor. Additionaly, initial fractography investigation were done, showing formation of the „film” on the tribosurface, containing elements preferably coming from the pad’s material (Fig. 5).