SHEAR-STRENGTH AT THE INTERFACE BETWEEN ALUMINUM AND CERAMICS IN MODEL COMPOSITES FABRICATED BY SQUEEZE CASTING

The shear strength at the ceramic-aluminum alloy interface of composit es fabricated by squeeze casting was measured. Ceramics used were SiC, Si3N4 and Al2O3, and pure aluminum, JIS AC8A and 2024 alloys were use d as matrices. The shear strength was measured by pushing out a rectan gular bar-like ceramic (cross-section: 5 mm x 10 mm) which were envelo ped in an aluminum alloy by squeeze casting. The good bonding between ceramics and aluminum alloys was obtained by squeeze casting. Fracture of pure aluminum matrix composites occurred in the aluminum site near the interface. However, fracture occurred at the interface in the cas e of SiC-AC8A alloy composite and the shear strength is slightly lower than that of the pure aluminum. Fracture behavior of AC8A matrix comp osites is classified into three stages; initial linear stage, debondin g and sliding. The shear strength was measured up to 573 K for each al loy, and decreased linearly with increasing temperature. The shear str ength is much related to the roughness of the ceramic surface and incr eases with the increase in the roughness. The influence of heat treatm ent on the shear strength was also examined. The shear strength of SiC -pure aluminum did not change by heating for 16 h at 823 K, but that o f SiC-2024 decreased.