Abstract
Aluminum-oxidation-energy powered engine has attracted our interest in replacing conventional engine powered by liquid fuel. This attraction is due to the high energy density and the reduction of carbon dioxide emission in the combustion of aluminum wires. During this process, we find that the arc-evaporation method can produce alumina nanopowder. Besides, the arc-evaporation method can reduce the production cost in comparison with traditional process. We design a new equipment to produce alumina nanopowder by the arc-evaporation method. First, it uses the heat which is produced by the arc-evaporation method to evaporate aluminum wire. And the aluminum gas reacts with oxygen to form alumina powder. Then, we analyze the collected powder, finding that the spherical particles produced from the combustion of aluminum wires are several hundreds of nanometers in diameters. Most of the powder is gamma-alumina. We use a two-stroke-cycle engine and an argon arc welder with the arc welding mode to stimulate the arc operation by touching and separating. Aluminum wires are feed through the spitfire nozzle and the graphite funnel which is designed to increase the vaporization rate of aluminum wires by reducing the heat loss of arcing. The arc is generated between negative electrode and aluminum wire by touching and separating when the piston is away from the top dead center. The results show that the efficiencies of the vaporization and the oxidation of aluminum wires are enhanced with the appropriate design of the spitfire nozzle. However, there are still some problems which require further works to be solved. First, the wires near the arc root might be thermally-expanded to seize the transport channel, resulting in no feed of Al wire. Second, the melting aluminum would be flowed back to the transport channel by the force of aluminum-oxidation and solidified due to cooling, resulting in seizing the transport channel.