Investigation On Popcorn-like Morphology Evolution Mechanism And Properties Of Al-(Bi,Sn)Based Water Vapor Hydrogen Production Powders

Al-based hydrolysis H2 production materials own advantages of low cost,low toxicity,easy preparation and high H2 production performance.However,there are shortcomings in H2 production by using liquid water to react with Al-based hydrolysis H2 production materials such as the reaction process is difficult to control so that the stable H2 flow for the fuel cell is difficult to gain,and the hydrolysis byproduct is not easy to recover.The technology of water vapor H2 production can solve the above problems.However,due to the passivation phenomenon of Al-based materials in air,the reaction temperature of traditional water vapor H2 production Al-based materials is more than 200?,which is not benefical for the application.In this study,a series of actived Al-based powders,which can react with water vapor with high Al/H2 conversion rate at normol temperature,were successfully prepared based on CALPHAD method and microstructure design.The mechanism of popcorm-like morphology evolution and the water vapor H2 production properties were studied in detail.The main results of this study are as follows:(1)A series of Al-(Bi,Sn)based water vapor H2 production powders are designed by CALPHAD method and microstructure design.These alloy powders are prepared by gas atomization method.And they show the popcorn-like morphology evolution phenomenon when they react with water vapor in ambient air.(2)The water vapor H2 production properties of Al-(Bi,Sn)base water vapor H2 production powders are studied.The results show that the Al-(Bi,Sn)based water vapor H2 production powders have good water vapor H2 production properties.The Al/H2 conversion of 85A1-Bi-Sn wt.%alloy powder with saturated water vapor at 50? can reach to 92.1%with a maximum H2 production rate of 80 ml/min·g.(3)The popcorn-like morphology evolution mechanism of Al-(Bi,Sn)based alloy powders is studied.It is found that the dispersed Bi-rich/Sn-rich/(Bi,Sn)eutectic/(Pb.Sn)eutectic particles could effectively activate aluminum letting the hydration layer lose the protective effect to aluminum,which leads the occurrence of sustainable hydrolysis reaction of aluminum.According to the experimental results,a special mechanism leading to the popcorn-like morphology evolution is proposed and verified by finite element simulation method.