| In this study,the CNTs-Al mixed reinforcement was synthesized in situ on the Al powder by chemical vapor deposition,the chemical vapor deposition using Ni as a catalyst.The CNTs-Al mixed reinforcement with Zn powder was mixed by short-time ball milling.Zn matrix composites were prepared by vacuum sintering.The microstructure of the composites was analyzed to optimize the chemical vapor deposition process to determine the optimal deposition of CNTs.The CNTs-Al mixed reinforcements were synthesized by chemical vapor deposition.The effects of catalyst content,reaction substrate size,reaction temperature,reaction time and reaction atmosphere on the yield and morphology of CNTs were investigated.The results show that the yield of CNTs increases with the increase of Ni content in the catalyst.When the Ni content in the catalyst is 20wt%,the yield of CNTs reaches the maximum value,and the Ni content continues to increase,and the yield of CNTs decreases.The particle size of the reaction substrate affects the yield of CNTs to a certain extent.The smaller the particle size,the higher the yield.The reaction temperature is higher at 580℃630℃.When the temperature is lowered or increased,the yield of CNTs decreases.The yield increased with the increase of reaction time.When the reaction time was 60 min,the yield of CNTs increased greatly,and the reaction time continued to prolong.The yield of CNTs remained basically unchanged.Different carbon source gases have a great influence on the yield of CNTs.When C2H2 is used as carbon source gas,the yield of CNTs is the highest.The ratio of carrier gas to carbon source gas also affects the yield of CNTs.The ratio of N2 to CH4 is At 8:1,the deposited CNTs were the most.the different types of carrier gases also affected the yield of CNTs.When N2 was used as the carrier gas,the yield of CNTs was the highest.（CNTs-Al）/Zn matrix composites were prepared by powder metallurgy technology.The effects of milling time,ball milling speed,molding pressure and sintering process on the dispersion of CNTs,density and hardness of composites were studied.On this basis,The effects of CNTs content on the microstructure and properties of composites were further explored,and the strengthening mechanism of CNTs in Zn matrix composites was discussed.The results show that after ball milling for 120 min at 300 rpm,the particle size distribution of（CNTs-Al）/Zn composite powder is uniform and the CNTs are well dispersed.During the pressing process,the density of the billet increases with the increase of pressing pressure and holding time.When sintered at 580℃for 6h and the content of CNTs is 2.0wt%,the composite mechanical properties are optimal.This is because the sintering process is too slow,the sintering process is slow,the material pores are too high,and the sintering temperature is too high,resulting in coarse grains.And the pores are large;if the sintering time is too short,the sintering is incomplete,the sintering time is too long,and the grains are excessively coarse.The strengthening mechanism of CNTs in composites is discussed.CNTs bear the load transmitted from the interface when the composite is deformed,and the dislocation is dense due to the difference of thermal expansion coefficient,which can also play the role of fine grain strengthening.The main strengthening mechanism of CNTs on the matrix mainly comes from the synergistic effect of load strengthening,dislocation strengthening and fine grain strengthening. |
