Research On Fabrication And Properties Of Mg-Zn Alloy Based Carbon Nanotube Composites

CNTs/ZM1 magnesium matrix composites were prepared by casting mechanical mixing method. This mainly studies the corresponding influences made by different quantities,dispersed state and surficial decoration of CNTs to the microstructure, mechanical properties and the friction and wear properties of ZM1 alloy as-cast and T6 heat treated condition. To make CNTs a better dispersed state in the magnesium alloy matrix, we studied the ball-milling method and ultrasonic stirring perform methods; To enhance the combination of CNTs and the magnesium body, we studied nickel coated oxidation technology.Scanning electron microscope(SEM), X-ray diffraction(XRD) and infrared spectroscopy(IR) were developed to characterize CNTs and magnesium matrix composites.The research results show that: nano nickel oxide prepared by homogeneous precipitation method can make itself adhere to carbon nanotubes well. When content of nickel oxide is 33%,carbon nanotubes can be coated by well-dispersed nano nickel oxide evenly,while the average diameter of nickel oxide particles is 20 nm with no agglomeration.;The precast block prepared by ball mill and ultrasonic stirring method can make CNTs coat on the zinc powder and the CNTs of precast blocks prepared by ultrasonic stirring method evenly disperses on the zinc powder particles, without obvious agglomeration;CNTs can refine the grains of the composite, and the grain refining effect becomes more obvious with the increase of CNTs added in within a certain range; CNTs can also significantly improve mechanical properties of the composite materials. The tensile strength,the elastic modulus and the hardness reach the peak value of respective 203.5 MPa, 48.3 GPa and 81.5 HV when the addition of CNTs reaches 1.0 wt %. When the content of CNTs is 1 wt %, ZM1 disposed by CNTs precast block which is prepared by ultrasonic stirring method performs better on mechanical properties than that is prepared by the ball mill precast block method and ZM1 disposed by CNTs precast block which is coated with nickel oxide then dispersed with ultrasonic stirring method performs better on mechanical properties than that is disposed by the uncoated one. The tensile strength, microhardness and elastic modulus of ZM1 composites with addition of 1.0 wt % CNTs were 208.7 MPa, 84.3 Hv and 48.7 GPa respectively; After T6 heat treatment, the influence of CNTs on the mechanical property of the composite is similar to that for the as-cast. The mechanical propertises of the samples treated using T6 with the same composition as as-cast samples are superior to that of as cast one, these peak values of tensile, elastic moduli and micro-hardness respectively reach the 211.3 MPa, Hv 83.4 and 48.0 GPa;When adding 1wt % CNTs, the mechanical properties of ZM1 become better when it is added with the precast block of ultrasonic stirring method than that of the ball mill method. The tensile strength, microhardness, ductility and elastic modulus of ZM1-1 wt % CNTs composite material reach 214.7MPa, 85.3HV, 6.6% and 48.2GPa ZM1 magnesium alloys treated withT6 manifeste as cleavage brittle fracture; with the addion of 1 wt % Carbon nanotubes, the alloy is characterized by brittle and ductile mixed fracture; when Carbon nanotubes addition is 1.5%, the alloy is characterized by cleavage and intergranular brittle mixed fracture;With the addition of CNTs, the wear ability of composites has a certain improvment, and the friction coefficient of the composite decreases with the increase of content of CNTs; the amount of wear of composites showed a trend of increase after the decrease at the beginning.