Study On Properties Of Silicon Carbide Composite Infiltrated By Aluminum Alloy

SiC ceramics are widely used in structural materials because of their high temperature strength and excellent wear properties,however,their shortcoming such as brittleness,poor anti-vibration performance,and difficulty in processing reduce the service life.The introduction of aluminum alloy to prepare SiC/Al composites is an effective method to improve the toughness of SiC ceramics and reduce the effects of vibration and noise.In this paper,SiC/Al composites were prepared by infiltrating Al-Ti-Si alloys.The effects of Si content and infiltration temperature on the microstructure of composites were studied.The infiltration mechanism was explained,and the damping capacity were analysis combined the hardness and strength.The scanning electron microscope and transmission electron microscope were used to study the interface structure,and the mechanism of the interface's influence on mechanical properties and damping capacity was revealed.In addition,the effect of Si content in the infiltrated aluminum alloy on the wear properties of the composite was also studied.The wear properties of the composite were improved by heat treatment.It was found that at the infiltration temperature,the aluminum alloy and Si in the SiC ceramic formed a eutectic,forming a channel to enter the ceramics.A Ti₃Si(Al)C₂ reaction layer was formed on the surface of the composite when infiltrated aluminum alloy with 5,10,15 wt.%Si at 900?.The bending strength of the composite was up to 376 MPa when infiltrated aluminum alloy with 10 wt.%Si at 900?.When the Si content was 15 wt.%,the high-temperature damping capacity of the composite was doubled compared to the original ceramic.The damping mechanism was mainly the dislocation-inducing mechanism at low temperature and the energy dissipation by SiC/Al interface frictional at high temperature.The SiC/Al interface was connected by eutectic Si formed during the solidification cooling process.When the Si content in the infiltrated aluminum alloy was less than 20 wt.%,more eutectic Si was formed during cooling and the interface bonding strength was higher.The wear experimental results showed that the Ti₃Si(Al)C₂ reaction layer undergoes plastic deformation during friction and wear.The formation of a friction oxide film improves the friction reduction performance of the composite,but the wear rate was increased due to the decrease in surface hardness.With the increased of Si content in the infiltrated aluminum alloy,the wearing mechanism was changed from abrasive wear to adhesive wear and oxidation wear.Through the heat treatment at 1000?for 12 h,the wear resistance of the composite was improved on the basis of ensuring the friction reduction performance.