Ž . Wear 233–235 1999 444–454 www.elsevier.comrlocaterwear Two-body abrasive wear of Al–SiC composites Kassim S. Al-Rubaie a , Humberto N. Yoshimura b , Jose Daniel Biasoli de Mello a, ) ´ a Laboratorio de Tribologia e Materiais, Departamento de Ciencias Fısicas, UniÕersidade Federal de Uberlandia, Campus Santa Monica 38400-902, MG, ´ ˆ ´ ˆ ˆ Brazil b Instituto de Pesquisas Tecnologicas de Sao Paulo-IPT, DiÕisao de Quımica-Materiais Inorganicos, AÕ. Prof. Almeida, 532, 05508-901 Sao Paulo, SP, ´ ˜ ˜ ´ ˜ Brazil Abstract The two-body abrasive wear behaviour of aluminium matrix composites reinforced with silicon carbide particles has been investigated. The metal matrix composites were fabricated by a powder metallurgy route involving a final hot extrusion step, with Al 1100 matrix and a-SiC reinforcement with mean sizes of 10, 27 and 43 mm, in the proportions of 5, 10 and 20 vol.%. Using a pin-on-disc apparatus, p two-body abrasion tests were carried out against silicon carbide and alumina abrasives with four different grit sizes. The microstructural characterisations were performed using light microscopy. The dominant wear mechanisms were evaluated using scanning electron microscopy. It was shown that SiC particles reinforcement improved the abrasion resistance against all the abrasives used. This p improvement generally was higher against alumina than against silicon carbide. The abrasion resistance increased with an increase in the volume fraction and size of SiC particles reinforcement. The results also showed that the abrasion resistance decreased with increasing p the relative abrasive penetration depth, until a critical value; above this limit, the abrasion resistance was generally independent of the penetration depth. q 1999 Elsevier Science S.A. All rights reserved. Keywords: Al–SiC composites; SiC reinforcement; Two-body abrasion; Abrasive particles; Wear mechanisms p 1. Introduction Ž . Metal matrix composites MMCs are increasingly be- ing used in the aerospace and automobile industries be- cause of their improved strength, stiffness and increased w x wear resistance over unreinforced alloys 1–5 . The com- monly used metallic matrixes include light metals such as aluminium, magnesium, titanium, and their alloys. The reinforcement can be in the form of fibres, whiskers and particulates. Widely used reinforcements are silicon car- w x bide, aluminium oxide and graphite 4,5 . Reinforcement of aluminium alloys with Al O or SiC has generally been 2 3 w x observed to improve wear and abrasion resistance 6–29 . While many investigations have been focused on the sliding wear behaviour of aluminium matrix composites w x 6–21 , there are relatively few results on the abrasion w x performance of these composites 20–29 . ) Corresponding author. Department of Materials SciencerMetallurgy, Tribology Group, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, UK. Tel.: q44-1223-334503; fax: q44-1223-334567; E-mail: jdbd2@cam.ac.uk w x Wang and Hutchings 24 studied the two-body abrasion of an alumina fibre-aluminium MMC against SiC abrasive using a pin-on-disc apparatus. The composites were made by liquid metal squeeze infiltration. They found that the abrasion resistance of the composites containing discontin- uous alumina fibres was higher by two to six times that of w x the unreinforced matrix alloy. Wang and Hutchings 24 also found a transition in wear behaviour, which was dependent on the abrasive particle size. They showed that, in abrasion against coarse abrasive particles, there is an optimal amount of reinforcement; higher volume fraction leading to decreased abrasion resistance owing to in- creased fragmentation and pull-out of the reinforcement. w x Lee et al. 26 investigated the effect of porosity, vol- ume fraction and size of silicon carbide particles on the abrasion resistance of powder metallurgy aluminium alloy 6061 matrix composites. They found that the abrasion resistance of the aluminium alloy decreased drastically with increasing porosity. However, for the composites, the porosity effect was less significant. They also found that the abrasion resistance of the composites increased as the amount of SiC increased. Also for the composites con- p 0043-1648r99r$ - see front matter q 1999 Elsevier Science S.A. All rights reserved. Ž . PII: S0043-1648 99 00185-4