Mechanical And Thermal Properties Of The Coaxial Carbon Nanotube@Boron Nitride Nanotube Composite

With the deepening of scientific research,scientists have creatively grown a composite structure of carbon nanotube coated with boron nitride nanotube,which is called coaxial carbon nanotube@boron nitride nanotube composite(CNT@BNNT).The novel structure of CNT@BNNT combines the advantages of both sides and shows excellent properties such as high strength and toughness,good thermal stability,strong oxidation resistance and high temperature resistance.At the same time,it overcomes the shortcomings of carbon nanotubes that are easy to be oxidized at high temperature and that the thermal conductivity of boron nitride is lower than that of carbon nanotubes.In this paper,molecular dynamics simulation is used to calculate the thermodynamic properties of CNT@BNNT and its interface thermal conductance with substrate copper(Cu)or substrate silicon(Si).Firstly,simulations are carried to explore the mechanical and thermal properties of CNT-(10,0)@BNNT(19,0).The stress of CNT(10,0)@BNNT(19,0)increases linearly then decrease with the increase of compressive strain,and the compressive Young's modulus is 0.856TP.The critical strain and Young's modulus of CNT(10,0)@BNNT(19,0)increase with the increase of the interaction force between the inner tube and outer tube.The thermal conductivity of CNT(10,0)@BNNT(19,0)decreases sharply at first and then tends to moderate with the increase of temperature in the range of 100 K to 1200 K.The specific value decreases from318.52 W/m/K to 65.62 W/m/K.In the range of compression strain 0 to 0.1,the thermal conductivity of CNT(10,0)@BNNT(19,0)obviously decreases with the increase of compression strain,and the specific value decreases from 196.57 W/m/K to 27.73 W/m/K.Secondly,simulations are carried to explore the interfacial thermal conductance of CNT-(10,0)@BNNT(19,0)and substrate Cu.The interfacial thermal conductance of CNT(10,0)-@BNNT(19,0)and Cu increases with the increase of temperature in the range from 100K to1000K.The specific value increases from 6.876×10~8 W/m~2/K to 9.393×10~8 W/m~2/K.There is a thermal rectification effect on the interface thermal conductance of CNT(10,0)@BNNT(19,0)and Cu.When CNT(10,0)@BNNT(19,0)is the hot end,the interface conductance is higher than that of Cu as the hot end at all temperatures.In the range of compression strain from 0 to0.1,the thermal conductance of CNT(10,0)@BNNT(19,0)and Cu increases with the increase of compression strain,and the specific value increases from 7.329×10~8 W/m~2/K to 13.463×10~8W/m~2/K.Furtherly,simulations are carried to explore the interfacial thermal conductance of CNT-(10,0)@BNNT(19,0)and substrate Si.The interfacial thermal conductance of CNT(10,0)-@BNNT(19,0)and Si increases with the increase of temperature in the range from 100K to1000K.The specific value increases from 4.537×10~8 W/m~2/K to 9.666×10~8 W/m~2/K.There is a thermal rectification effect on the interface thermal conductance of CNT(10,0)@BNNT(19,0)and Si.When CNT(10,0)@BNNT(19,0)is the hot end,the interface conductance is higher than that of Si as the hot end at all temperatures.In the range of compression strain from 0 to 0.1,the thermal conductance of CNT(10,0)@BNNT(19,0)and Si increases with the increase of compression strain,and the specific value increases from 4.798×10~8 W/m~2/K to 7.940×10~8W/m~2/K.The results of this paper can provide some references for the research and application of CNT@BNNT.