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The wettability plays a decisive role in the mechanical performances of the aluminum matrix composites reinforced with carbon nanotubes (CNTs). In this paper, novel Cu nanoparticles-coated CNTs (Cu@CNTs) were prepared successfully by the liquid phase reduction method to enhance the wettability of CNTs in aluminum melt. The microstructure, contact angle, and interfacial structure of aluminum liquid on Cu@CNTs substrate at high temperature were investigated by scanning electron microscopy (SEM) and sessile drop method in detail. By incorporating Cu nanoparticles on the surface of CNTs, the contact angle was reduced from 133° to 91°, indicating a significant improvement in the wettability of CNTs in aluminum melt. The atomic diffusion of Cu and Al elements leads to a remarkable improvement of wettability for Al-Cu@CNTs model. The coating of CNTs provides a new insight for strong wettability in high-performance aluminum matrix composites. [Display omitted] • Cu-coated CNTs were successfully synthesized via compound reduction method with ethylene glycol and N 2 H 4· H 2 O reductant. • With the contact angle reducing from 133° to 91°, the wettability of CNTs to aluminum melt was improved by coating Cu nanoparticles. • The better wettability of Cu@CNTs to aluminum melt attributes to small amount of element Al can react with Cu on Al-Cu@CNTs interface to form AlCu or Al 2 Cu, which can greatly enhance the bonding strength of composites. [ABSTRACT FROM AUTHOR]

Controlling the interfacial interaction is a prerequisite for the preparation of aluminum matrix composites reinforced by carbon nanotubes (CNTs) with high performance. In this paper, Cu-coated CNTs fabricated by the compound reduction method were applied to control the interfacial interaction between carbon nanotubes and aluminum matrix for improving the interfacial bonding and mechanical properties of aluminum matrix composites. The microstructure, interfacial structure, interfacial interaction, and mechanical properties of Cu-coated composite were studied in detail. The in-depth study results show that Cu nanoparticles act as a bridge connecting the carbon nanotubes and matrix and forming Al 2 Cu intermetallic, which is in favour for better dispersion of carbon nanotubes and interfacial bonding. In addition, Cu nanoparticles are preferentially deposited at the defects of carbon nanotubes to repair the defects and inhibit the formation of brittle Al 4 C 3 phases. As a result, Cu-coated composite displays the superior strength with yield strength and ultimate tensile strength of 203 MPa and 287 MPa, which are 45% and 38% higher than those of matrix (140 MPa and 207 MPa) and 8% and 12% higher than those of uncoated composite (188 MPa and 256 MPa), respectively. The introduction of Cu nanoparticles can significantly improve the interfacial bonding strength of Cu-coated composite, ensuring the effective transfer of load from the matrix to carbon nanotubes and exerting its strengthening and toughening effect. [ABSTRACT FROM AUTHOR]

Novel CNTs modified with ZrO 2 nanoparticles (ZrO 2 @CNTs) were selected as the reinforcement to prepare ZrO 2 @CNTs/2A70 via high-intensity ultrasonic assisted casting. The microstructure, wettability, interfacial bonding, and mechanical properties of ZrO 2 @CNTs/2A70 composites were researched. After modifying ZrO 2 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 ZrO 2 nanoparticles were spontaneous in initial stage, and then required additional energy from external environment. TEM analysis demonstrated that ZrO 2 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)ZrO 2 //(010)Al, (010)ZrO 2 //(100)Al, (010)ZrO 2 //(100)Al can form semi-coherent interface, indicating a good lattice space matching between ZrO 2 and Al matrix. The 1.5 wt% ZrO 2 @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 ZrO 2 @CNTs. [Display omitted] • A novel CNTs modified with ZrO 2 nanoparticles are successfully prepared. The contact angle of CNTs to Al reduced from 140.70° to 116.85°. • The (010)ZrO 2 //(010)Al, (010)ZrO 2 //(100)Al, (010)ZrO 2 //(100)Al form semi-coherent interface, indicating a good lattice space matching between ZrO 2 and Al. • 1.5 wt% ZrO 2 @CNTs/2A70 composites exhibited excellent mechanical properties. [ABSTRACT FROM AUTHOR]