Evaluation of particle release during cleaning of coated surfaces with pulsed Nd:YAG laser

The released particles during laser-based surface ablation of an epoxy resin coating were investigated for their number, size, mass and chemical composition. The laser used was a pulsed Nd: YAG laser with a maximum average power of 91 W. During the experiments, the applied laser power was investigated as a varying parameter. With the highest power, a maximum particle count of 4.3*108 particles/cm3 was measured, which corresponds to a mass of approximately 55 mg/m3. With decreasing laser power, the particle loading of the aerosol decreases. The particle sizes are bimodal distributed between 10 nm and approximately 3 & mu;m. The first peak is at 34 nm and the second peak is at 630 nm. In terms of number, the nanoparticles dominate the distribution. During the analysis of the particles, fractal and spherical particles were determined, whereby the fractal particles are mainly in the nanometre range and the spherical particles mostly in the & mu;m range. The chemical analysis of the particles showed that they consist of carbon and hydrogen.