Pulsed laser modification of plasma-sprayed coatings: Experimental processing of hydroxyapatite and numerical simulation

A pulsed CO2 laser was used to treat plasma-sprayed hydroxyapatite coatings. Pulses of 0.74 ms duration and powers equal to 41.6 and 45.3 W were focused onto a 300 μm spot of the coatings surface. The laser beam was scanned with speeds of 6.4 and 9.6 mm/s. The morphology of laser-treated deposits was observed by scanning electron microscopy (SEM) and the crystal phases identified using X-ray diffraction (XRD). This technique enabled also the determination of quantitative phase composition. The laser treatment process was modeled using the Fusion-2D, software and the temperature fields and depth of molten material were predicted. The latter were compared with the experimental ones found in metallographically prepared cross-sections. A reasonable convergence between the model and experiment was achieved after careful optimisation of initial material parameters as such coefficient of optical absorption and emissivity.