Effect of Ni coating thickness on microstructure and properties of CF/Al composites prepared by vacuum pressure infiltration process

In this paper, Ni coatings with different thickness (∼0.21 μm, ∼0.46 μm, ∼0.65 μm, ∼0.76 μm) were applied on the surface of carbon fiber (CF) by electroless plating process and carbon fiber aluminium matrix (CF/Al) composites were prepared by vacuum pressure infiltration process at 1023 K. The results show that when the coating was relatively thin, the coating was not uniform due to the inconsistent surface activity of CF. When the coating was relatively thick, there was a certain amount of stress inside the coating, which results in poor bonding between the coating and CF. As a result, it was prone to shedding during Al liquid infiltration and a large number of Al–Ni compounds were formed in the matrix. The compounds have a certain fracture brittleness, which is not conducive to improving the tensile properties of the composites. When the thickness of Ni coating was 0.46 ± 0.017 μm, the appropriate diffusion reaction of the coating in the matrix changed the bonding form of the interface from physical bonding to chemical bonding. Under this condition, the strength of CF/Al composites was the highest. It has a tensile strength of 110.58 ± 1.6 MPa, which is approximately 83% higher than that of the pure Al matrix.