Preparation And Mechanical Property Of B-doped Carbon Nanotubes Reinforced Magnesium Matrix Composites

Carbon nanotubes (CNTs) are considered as the perfect reinforcement for composites because of its high strength, high module, outstanding physical performance, and extreme small size. The interface between CNTs and magnesium is closely related to the properties of CNTs reinforced Mg matrix composites. Therefore, it is very important to investigate how to modify the interface between Mg and CNTs for improving the properties of Mg matrix composites.In this thesis, B-doped CNTs was prepared by calcining the mixture of B₂O₃ and CNTs at different temperatures. The composite materials with different content of CNTs and Boron-doped CNTs was prepared by using the powder metallurgy technique followed by hot extrusion. The microstructure, compression strength and microhardness of the CNTs/Mg composite bulks were tested. The fracture surface of the CNTs/Mg composite bulks was observed. Then the CNTs/Mg composites films were produced by vacuum evaporation. The interface between Mg and CNTs of the CNTs/Mg composites films and bulks was investigated.The results show that B-doped CNTs has been successfully prepared. The content of B-doping in CNTs increased with the calcination temperature, and a maximum was reached at a critical temperature of 1150°C. A simultaneous increase in compression strength and microhardness was found for the CNTs/Mg nanocomposites until a CNTs content threshold of 0.5 wt.% with the compressive strength of 405.9MPa and the microhardness of 59.4HV. The properties of B-doped CNTs/Mg is better than original CNTs/Mg, when they have same contains of CNTs. The fracture appearance anslysis and TEM obveration indicated the wetting property and interfacial binding in the B-doped CNTs/Mg composite is better than that in the original CNTs/Mg composite.