Properties of Hybrid-Reinforced Aluminum Matrix Composites for Precision Instruments

Hybrid-reinforcement SiC/Gr/Al composites were fabricated by squeeze-casting technology, to provide a novel solution to machinable materials for precision instruments. The effect of flake graphite particles on mechanical properties, machinability, dimensional stability and coefficient of thermal expansion was studied. With the addition of 5% graphite particles in the SiC/Al composites, the tool life during cutting is prolonged by 40% and the tensile strength, elastic modulus and specific modulus are 405 MPa, 150 GPa and 51 GPa cm3/g respectively. The micro-yield stress of SiC/5%Gr/Al composite is higher than 300 MPa and the linear CTE is 11.6 × 10−6 °C−1. The properties of SiC/Gr/Al composite were in contrast to conventional materials of precision instruments and the advantages in application are discussed.