‘Thermal spraying’ is a generic term used for processes wherein the sprayed layer is built up by partially melting or deforming the powder material to be coated in a high temperature (e.g. flame, plasma, detonation spray) or cold temperature zone (e.g. cold spray) and propelling the molten droplets onto the substrate in the form of splats.

Thermal spray processes are used to produce thick-film coatings to combat surface degradation of engineering components.

These processes can be relatively simply for single elastic impacts, but the situation is more complicated in spraying where the particles undergo significant plastic deformation and fragmentation (Fig. 5), there are many, perhaps overlapping events and a number of secondary processes (such as the collapse of particle agglomerations and phase changes) going on.

Dr Nadimul Haque Faisal is currently working in collaboration with Dr Saurav Goel at Queen’s University of Belfast investigating through LAMMPS molecular dynamics (MD) simulations applied to material property evaluations of atomistic scale mechanism of powder particles impact during thermal spray coating formation.

FMR Figure 5A  FMR Figure 5B

Figure 5: LAMMPS molecular dynamics simulation of thermally sprayed particle impact: (a) before impact, and (b) after impact behaviour of particle and substrate, and particle flattens and substrate surface atoms plastically deforms.