Reserch On Synthesis Of Carbon Nanotubes And Nanospheres Prepared By Gaseous Detonation(Deflagration) Method

Carbon nanotubes and carbon nanospheres have a wide range of applications in the 21 st century due to their excellent properties.Gas phase detonation is a new method to synthesize carbon nanotubes and carbon nanospheres,which has the advantages of simple equipment,easy realization,and large amount of products.In this paper,the multi-walled carbon nanotubes were successfully synthesized by gas-phase detonation for the first time,and the related changes and growth mechanism were explored.The main contents are as follows:1.In this paper,the feasibility of synthesis of carbon nanotubes and carbon nanotubes by gas detonation is analyzed theoretically.The classical detonation theory is used to calculate the detonation pressure,detonation temperature,detonation velocity and detonation velocity.The detonation velocity of CH4 was 2240 m / s,acetylene was 2900 m / s and benzene was 2160 m / s.The detonation velocity of methane,acetylene and benzene was measured by high speed photography experiment.The propagation process of mixed gas explosion was also observed.2.In this paper,the explosion process of the mixed gas in a closed detonation tube is numerically simulated.When the methane / oxygen = 1: 1,the maximum pressure in the detonation tube reaches 2.6 MPa,which is close to the calculated value of 2.1 MPa.By simulating the operating conditions of different ratio of acetylene and oxygen,it was found that when the oxygen content increased,the reaction rate accelerated and the velocity of flame front propagated to the right was accelerated.By simulating different operating conditions of benzene and oxygen,when benzene / oxygen = 1: 2,a large amount of carbon is generated and the calculated detonation temperature is 3400 K,which is close to the simulation.3.Carbon nanotubes were successfully synthesized by using methane and oxygen as exploding sources,ferrocene as precursor and cha nging the initial temperature and ferrocene mass respectively.In addition,acetylene was used as a carbon source to investigate the synthesis of carbon nanotubes.The synthesized products were analyzed by XRD,TEM,RAMAN and TGA.The results show that the synthesized multi-walled carbon nanotubes are bamboo-like and have high degree of graphitization under the high temperature and high pressure of detonation.The graphitization degree of carbon nanotubes increases with the increase of precursor mass,and the defects of carbon nanotubes decrease.When the carbon nanotubes were prepared at different initial temperatures,the amount of carbon nanotubes produced decreased and the degree of graphitization decreased with the increase of the initial temperature,but the wall of the carbon nanotubes became smooth.So that the temperature of the synthesis between 110 ~ 130 ° C is more appropriate.When acetylene gas is used instead of methane,the carbon nanotubes are not formed in the synthesized products,but similar carbon nanobelt is formed and the products are highly graphitized.4.The detonation of benzene and oxygen by gas phase detonation was used to investigate the effect of initial concentration of reactants on gas phase detonation synthesis of nanomaterials.It was found that the size of the synthesized carbon nanospheres was between 30 and 50 nm.With the increase of the oxygen concentration ratio,the grain size of the product decreased and the degree of agglomeration decreased.And when the oxygen-to-benzene ratio is lower than 1.25,an explosion-proof phenomenon occurs.Finally,the mechanism of gas-phase detonation synthesis of carbon nanospheres is explored.The process of detonation undergoes four processes,with rapid collisions and cohesion,which make the carbon particles gradually bond and grow up to form nanoparticle carbon sphere.