Using magnesium to maximize heat generated by reactive Al/Zr nanolaminates

作者：Overdeep Kyle R^*; Livi Kenneth J T; Allen David J; Glumac Nick G; Weihs Timothy P

来源：Combustion and Flame, 2015, 162(7): 2855-2864.

DOI：10.1016/j.combustflame.2015.03.023

• Reactive nanocomposites
• Bomb calorimetry
• Aluminum
• Zirconium
• Magnesium

In this study, we explore the effect of magnesium content on the ability of reactive nanocomposite foils to generate heat, by comparing three chemistries: Al:Zr, Al-8Mg:Zr, and Al-38Mg:Zr. These correspond to foils with alternating aluminum and zirconium layers where the Al is either pure, an 8 at%Mg alloy, or a 38 at.%Mg alloy, respectively. Measurements performed in a specially designed bomb calorimeter show that Al-8Mg:Zr foils perform the best, generating the greatest gravimetric heat in air, oxygen, and nitrogen environments. Both Mg-containing foils release a visible plume of particles and vapor upon reacting, which was recorded with a high speed camera. This ejected mass includes Mg vapor and particles of all three metals. Both the vapor and particles oxidize rapidly in air, resulting in single metal-oxide particles. The reacted foils, particularly the Al-8Mg:Zr samples, contain voids and higher levels of oxygen and nitrogen throughout their thicknesses than reacted Al:Zr foils. To explain the higher heats of reaction for the Al-8Mg:Zr foils, we suggest that the out-diffusion and evaporation of Mg generates a high concentration of vacancies that enhance oxygen and nitrogen diffusion throughout the foil, thereby increasing the degree of oxidation and nitridation.

• 出版日期2015-7