Study On Fabrication, Microstructure And Properties Of CNTs/Mg Magnesium Matrix Layer Composites

The nacre exhibit excellent mechanical properties and the perfect match of strength and toughness with a unique "brick-and-mortar" structure,which is composed of 95vol% of aragonite calcium carbonate and 5vol% of the polymer.In this paper,pure magnesium and carbon nanotubes were used as micro-layers and nanometer layers respectively to construct the bionic multi-layer structure by electrophoretic deposition process and lamination preparation technique.The CNTs/Mg bionic Layered composites was prepared by vacuum hot pressing and rolling.The microstructures of the prepared materials were characterized by OM,SEM and TEM.The mechanical properties of the prepared materials were also investigated.The effects of electrophoretic deposition,hot pressing and sintering on the properties of pure magnesium and its composites were investigated.We also analysis the relationship of the process-structure-performance.The results show that the dispersion of carbon nanotubes is improved and the agglomeration tends to decrease,and the prepared carbon nanotube suspensions are more stable.The magnesium oxide particles are present on the surface of the magnesium film without pickling,and the particles are distributed without carbon nanotube deposition,and can cause local microcracks.There was a significant positive correlation between the content of carbon nanotubes on the magnesium and the deposition time,and the content of carbon nanotubes increased with the deposition time,and the homogeneity of the carbon nanotubes was also improved.With the increase of electrolyte content,the deposition rate of carbon nanotubes increases,but when the electrolyte content is too much,it will agglomerate due to excessive deposition of carbon nanotubes.The ultrasonic time will affect the dispersion of carbon nanotubes in the suspension,which will affect the dispersibility of the carbon nanotubes on the magnesium film.After ultrasonic treatment,the carbon nanotubes will be reduced to a certain extent and the dispersibility will be improved.Deposition voltage is too small,will lead to a very small amount of carbon nanotubes deposition,magnesium base exposed phenomenon is more serious,with the deposition voltage increases,the dispersion has been improved.The factors that affect the microstructure of the material during the sintering process are temperature,and as the temperature increases,the grain size grows and the addition of a small amount of carbon nanotubes does not significantly change the grain size.The mechanical properties of pure magnesium and its composites have been improved by adding the pure magnesium and its composite materials compared with the uncoated pure magnesium and its composite materials.The mechanical properties of the composites Elongation significantly improved.The strength of pure magnesium and its composites increased first and then decreased with the increase of rolling deformation.Compared with the same deformation of pure magnesium and its different deposited composite materials can be found,compared with pure magnesium composite materials,the strength has been improved.In the state of sintering and low deformation rolling,the strength of composites is relatively obvious.When the deformation increases to a great extent,the strength of pure magnesium is almost flat with that of composite material,and the elongation is decreased.The composite material is subjected to a large amount of deformation.