Effect of colloidal graphite on properties of low temperature metal-resin composite bond

The strength, the hardness, the microstructure and the reaction bonding mechanism of the composite bond were studied by adding mass fraction of 0~0.4% trace colloidal graphite to the aluminum-based metal-resin composite bond. The results show that when the sintering temperature is 360 ℃, the holding time is 5 min, and the holding pressure is 2 100 N/cm², with the increase of the mass fraction of colloidal graphite, the density of the composite bond first decreases, then increases and finally decreases; the hardness, the strength and the elastic modulus all increase first and then decrease. When the added mass fraction of the colloidal graphite is 0.2%, the hardness and the strength of the composite bond reach the maximum values of 61.5 HRB and 250 MPa, respectively, and the density and the elastic modulus of the composite bond are moderate. Trace colloidal graphite can react with Al in the composite bond to form a small amount of Al₄C₃, which promotes the formation of three-dimensional cross network structure and improves the properties of low-temperature metal-resin composite bond.