Deposition mechanism of dry sprayed ceramic particles at room temperature using a nano-particle deposition system

The nano-particle deposition system (NPDS) is a new dry spray process used to deposit metal and ceramic particles at room temperature. Low temperature deposition techniques for metals and ceramics that involve particle spraying include the NPDS, cold spray, and aerosol deposition methods. These are widely used to minimize thermal damage to the substrate when fabricating metal or ceramic layers. To optimize the process conditions for the intended applications and improve the deposition quality one must understand the mechanism of particle deposition at room temperature. The bonding mechanism in metal particle deposition by the cold spray method has already been researched. Adiabatic shear instability near the particle/substrate interface due to plastic deformation was reported to be the bonding mechanism for metal particles below the melting temperature. However, the bonding mechanism of ceramic particles has not been fully determined. This study assessed the bonding of ceramic particles by NPDS using numerical analysis and experimental results. A bonding mechanism is suggested after considering the experimental results for shock compaction, which is a process similar to that of the NPDS. The suggested deposition mechanism for ceramics involves the fragmentation of submicron ceramic particles into nanoparticles and the successive impact of submicron particles, which provides sufficient bonding energy, with heat and high pressure, to nanoparticles fragmented by the shock wave. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.