Effect of MWCNTs content on microstructure and mechanical properties of MWCNTs/Ag composites

Multi-walled carbon nanotubes (MWCNTs) were coated by silver using chemical plating, MWCNTs/Ag composite powders were fabricated by high energy ball milling, and MWCNTs reinforced silver composites were obtained with powder metallurgy method. Morphologies of the composite powder and distribution of MWCNTs in the composite were analyzed by scanning electron microscopy. The effect of the MWCNTs content on the mechanical properties of the composites was studied. The results show that Ag particles gather to larger secondary particles after ball milling and the degree of aggregation increases with the increase of MWCNTs content. The MWCNTs present severe aggregation in the composites when the volume fraction of MWCNTs exceeds 10% (volume fraction). With the increase of the volume fraction of MWCNTs, strength and hardness of the composite first increase and then decrease. The composite containing 8% MWCNTs exhibits optimal mechanical properties with tensile strength of 297 MPa, yield strength of 245 MPa, and hardness of 80.1 HV0.1. The MWCNTs/Ag composite shows obvious plastic fracture with many dimples on the fracture surface. Pull-out of the MWCNTs illustrates the load transferring and strengthening effect of MWCNTs. © 2016, Science Press. All right reserved.