Measuring Heat Production from Burning Al/Zr and Al/Mg/Zr Composite Particles in a Custom Micro-Bomb Calorimeter

Area of Science:

• Materials Science
• Combustion Chemistry
• Nanotechnology

Background:

• Nanocomposite materials offer unique properties due to their high surface area to volume ratio.
• Understanding combustion behavior is crucial for developing advanced energetic materials.

Purpose of the Study:

• To investigate the combustion efficiency of Al:Zr, Al-8Mg:Zr, and Al-38Mg:Zr nanocomposite particles.
• To determine the influence of particle size, composition, and dispersion on combustion performance.
• To explore the vaporization dynamics and flame characteristics during combustion.

Main Methods:

• Fabrication of nanocomposite particles using physical vapor deposition (PVD) and ball milling.
• Combustion experiments conducted in a custom micro-bomb calorimeter under 1 atm O2.
• Analysis of combustion heat, particle sintering, and oxide formation.

Main Results:

• All particles achieved 60-70% of theoretical maximum heat of combustion, exceeding thin films due to higher surface area.
• Particle sintering mitigated size and geometry effects, highlighting the importance of dispersion.
• Increased Mg content led to lower temperature vaporization and additional sintering stages.
• Formation of mixed Al and Mg nano-oxides suggests high vapor-flame temperatures (>2700 K).

Conclusions:

• Al-Mg-Zr nanocomposites exhibit significant combustion efficiency, influenced by surface area and Mg content.
• Particle dispersion is critical for maximizing performance by preventing sintering.
• The observed high combustion temperatures indicate potential for agent defeat applications.