Enhancing the wettability and interface bonding in carbon nanotubes reinforced 2A70 alloy by the coating of ZrO2

Abstract

Novel CNTs modified with ZrO2 nanoparticles (ZrO2@CNTs) were selected as the reinforcement to prepare ZrO2@CNTs/2A70 via high-intensity ultrasonic assisted casting. The microstructure, wettability, interfacial bonding, and mechanical properties of ZrO2@CNTs/2A70 composites were researched. After modifying ZrO2 on the surface of CNTs, the contact angle of CNTs to 2A70 melt reduced from 140.70° to 116.85°. Thermodynamic calculation indicated that the wetting processes of ZrO2 nanoparticles were spontaneous in initial stage, and then required additional energy from external environment. TEM analysis demonstrated that ZrO2 nanoparticles were uniformly distributed on the surface of CNTs, and could lock the CNTs in matrix, enhancing the interfacial bonding of CNTs-Al. The (010)ZrO2//(010)Al, (010)ZrO2//(100)Al, (010)ZrO2//(100)Al can form semi-coherent interface, indicating a good lattice space matching between ZrO2 and Al matrix. The 1.5 wt% ZrO2@CNTs/2A70 composites manifested excellent mechanical properties and the ultimate tensile strength reached 256.2 MPa, which were 21.47 % higher than that of the matrix (210.9 MPa). The improved mechanical properties may be attributed to the efficient load transfer of ZrO2@CNTs.