Synthesis of Al-B system nanostructures by interaction of disperse aluminium with boron and diborane in arc discharge plasma

Experimental studies of aluminium boride synthesis as a result of interaction of disperse aluminum with diborane B2H6 and disperse boron in a flow of thermal plasma of different composition generated in electric arc plasma torch have been carried out. Experimental work on the synthesis of aluminium boride nanoparticles from elements (a mixture of disperse aluminum and boron) has shown the possibility of obtaining in thermal plasma arc discharge of such phases of the boride as AlB12 and AlB31. The specific surface of the powders obtained is from 3 to 27 m2/g. According to X-ray phase analysis, the powders obtained, except for aluminum boride phases, also contain boron, aluminum, aluminum nitride and boric acid phases. The greatest yield of aluminum boride phases is provided by using the nitrogen plasma with hydrogen and enthalpy 4.5 kWt∙h/m3 in the reactor with increased high-temperature zone. The use of gaseous diborane made it possible to eliminate restrictions on the evaporation of boron particles but did not provide an opportunity to obtain aluminum borides in the plasma-chemical process. It was concluded that it is necessary to perform quenching of high-temperature gas flow containing boron and aluminum vapor to form aluminum borides from the gas phase in plasma-chemical synthesis. Such an approach should ensure that the temperature is reduced to the values at which aluminum borides are stable and that the formation of aluminum boride nanoparticles will occur as a result of condensation from the gas phase under these conditions.