The Preparation And Performance Of Core-shell Al@PDA@MOFs Composites

In order to maintain the reactivity of nano-Al,and modify the reaction performance of nanothermites,polydopamine(PDA)was coated on the surface of nano-Al as a protective layer.Then two kinds of core-shell Al@PDA@MOFs composites ware constructed by self-assembly method.The micromorphology,reaction performance and growth mechanism ware investigated by XRD,FTIR,SEM,TEM,EDS and DSC.The core-shell Al@PDA@Cu(NTZ)(N₃)composites has better micromorphology and reaction performance,compared to Al@PDA@Cu₃(BTC)₂.Besides,the combustion performance was furtherly studied via ignition test,combustion flame propagation test and P-t test.The main conclusions and results were as follows:(1)The morphology of PDA coating on the nano-Al surface is shallow groove-like.The relationship between thickness e of PDA layer and coating time t is e=1.96t^0.21,and when t is 5h,the PDA coating layer shows the best performance.Besides,compared with pure nano-Al,the presence of the PDA coating layer can effectively maintain the activity of the nano-Al particles.(2)The Al@PDA@Cu₃(BTC)₂ is an irregular bulk core-shell structure composite with spherical Al@PDA as the core and Cu₃(BTC)₂ as the shell.Its size is about several hundred nanometers.Compared with the Al@Cu₃(BTC)₂ composites,the presence of the PDA coating layer can effectively inhibit the self-nucleation of Cu₃(BTC)₂,significantly promoting mass and heat transfer during the solid-solid aluminothermic reaction.In addition,compared with the Al@PDA-Cu₃(BTC)₂ prepared by ultrasonic mixing,the antistatic of core-shell Al@PDA@Cu₃(BTC)₂ composites significantly decreases by 0.26k V.(3)The Al@PDA@Cu(NTZ)(N₃)is a"pomegranate-like"core-shell structure composite formed by Al@PDA particles dispersing in Cu(NTZ)(N₃).Its diameter is2?5?m.Compared with Al@Cu(NTZ)(N₃),the presence of PDA coating layer can promote obviously mass and heat transfer during the solid-solid aluminothermic reaction.In addition,compared with the Al@PDA-Cu(NTZ)(N₃)prepared by ultrasonic mixing,the antistatic of the core-shell Al@PDA@Cu(NTZ)(N₃)composites significantly decreases by 0.62k V.(4)Compared with Al@PDA-Cu(NTZ)(N₃)prepared by ultrasonic mixing,the ignition test indicates that the maximum flame height of the core-shell Al@PDA@Cu(NTZ)(N₃)increases by 0.25cm.The flame propagation test shows that the linear relationship between L and t was L=1.61t-1.41(R²=0.99175).The average burning rate of the latter reduces by 1.40m/s with more stable combustion performance The P-t test demonstrates that P_max of the core-shell Al@PDA@Cu(NTZ)(N₃)increases by 0.27MPa.