Synthesis and coating of copper oxide nanoparticles using atmospheric pressure plasmas

Metals and metal oxides are well-known catalysts in many applications. TNO investigates metal and metal oxide nanoparticles as catalysts in rocket and gun propellants. Using nanosize particles allows to tune the curing, mechanical or ballistic properties of the propellant, but to avoid undesired chemical side-reactions a coating of these nanoparticles is sometimes desirable. As a model compound copper oxide was selected. Two atmospheric plasma techniques are presented for synthesis of nanoparticles with suitable coating layers. The first technique is based on injection of existing copper particles (30 nm) in a dielectric barrier discharge. The second technique is based on the combination of a thermal wire arc technique and a non-thermal dielectric barrier discharge. Copper nanoparticles are synthesised via evaporation of copper wire followed by nucleation. Coating takes place in the dielectric barrier discharge zone. The thermal plasma synthesised nanoparticles have been characterised by a narrow size distribution and a main size around 50 nm. For both techniques evaporation of liquid acetone and methyl methacrylate have been used to provide gas phase coating precursors. The coated particles are collected on polycarbonate membranes and TEM grids to be characterised by SEM and TEM. The results show nanoparticles coated with a 5 to 10 nm thick carbon layer.