Fabrication of Al-Based Composites Cylinder Reinforced with <i>In Situ</i> Si/Mg₂Si Particles and the Research of its Bench Test

Abstract

The centrifugal casting process was adopted to fabricate Al-30Si-8Mg composites tubes reinforced with in-situ particles, which was used to produce the cylinders used in 149cc engine by high pressure die casting. The relations between the microstructures along the radial direction and the hardness and wear resistance of the casting were researched. The internal surface of the cylinder was treated and a bench test for the engine was carried out. The results show that, 1) a large number of primary Si/Mg2Si particles are segregated and enriched in the inner layer of the Al-30Si-8Mg casting, while no particle is in the outer layer, and the maximum particle volume fraction is up to 31.9 vol. %; 2) the region which has more primary particles, the hardness value is higher, and the wear resistance is better as well in the casting; 3) the cylinder assembled on the air-cooled engine successfully passes through the endurance test for 200 hours, and the maximum output power and torque reach 8.18 KW and 10.77 N·m, respectively, while a slight scuffing occurs on the internal surface of the cylinder in the later phase of the test.