Preparation And Properties Of Aluminum- Based Hydro-reactive Materials

A series of activated aluminum-based materials were prepared by high-energy ball milling in argon atmosphere. Scanning electron microscopy(SEM), particle size distribution test, specific surface test(BET) and thermal gravimetric(TG) were used to characterize the properties of activated aluminum-based materials. The experimental results show that the high-energy milling is an effective way to improve the hydro-reactivity of aluminum-based materials. Addition of the bismuth with a low melting point in the process of ball mill can further enhance the reaction activity of Al-based hydro-reactive materials. The hydrogen generation reaction rate in the fast stage is 210.7 mL?min-1?g-1. The total yield of reaction can reach 71.2%.Hydrolysis rate and efficiency of aluminum-based materials are influenced by multiple factors. Since ball-milled aluminum-bismuth material can hydrolyze fast with seawater, a series experiments were conducted to study the hydrolysis of activated aluminum-bismuth material with seawater. Several parameters influenced the hydrolysis reaction of activated aluminum-bismuth materials were investigated in the experiments, including content of bismuth, aluminum/water mass ratio, initial water temperature and different kinds of water. The experimental results show that the higher the initial water temperature was, the more complete the hydrolysis reaction was. With the increase of the content of bismuth, the hydrolysis reaction rate and efficiency are increased,when the content of bismuth reached 5wt%, the hydrolysis reaction wouldn't get an obvious promotion when more bismuth added in. For the aluminum-5wt% bismuth composite, the optimum aluminum/water mass ratio was obtained to be 1:60. For aluminum-bismuth materials, the initial reaction rate in 4% of the NaCl solution is greater than the initial reaction rate in seawater, the initial reaction rate is minimal in pure water, and concerned of the hydrogen production, the hydrogen production in seawater is greater than that in 4% of the NaCl solution, the hydrogen production is minimal in pure water.The addition of low melting point metal bismuth can greatly improve the reaction activity of aluminum-based materials. The SEM, XPS and XRD are used to characterize the aluminum-bismuth material and its hydrolysis products in different reaction stages with seawater. The results showed that the process of ball milling can peel off the oxide layer on the surface of aluminum powder and form a lamellar structure, which increases the contact area of the water. That is beneficial to the hydrolysis reaction of aluminum; Bismuth is uniformly embedded in the aluminum powder in the surface, on the one hand, The reaction between bismuth and seawater, which is converted into(BiO)2OHCl, destroyed the surface oxide layer of aluminum; In the other hand, the open potential of aluminum-bismuth is less than that of pure Al, so less energy is needed to form a large number of micro cell reaction by ion exchange.They are beneficial to the reaction of aluminum with seawater.And then, the high activity aluminum-bismuth powders?the ball milling of aluminum powders and raw aluminum powders were applied to hydro-reactive metal fuel propellants to study their combustion performance. The results show that the aluminum powder prepared by high energy ball milling has higher combustion efficiency in the combustion of hydro-reactive metal fuel propellants. The reaction efficiencies of propellants of aluminum milled with the low melting point bismuth are further improved. They have high burning rate and combustion heat.