Temporal Evolution of Pressure Generated by a Nanosecond Laser Pulse Used for Assessment of Adhesive Strength of the Tungsten-Zirconium-Borides Coatings

The article presents theoretical and experimental study of shock waves induced by a nanosecond laser pulse. Generation of surface plasma pressure by ablation of the graphite absorption layer in water medium and shock wave formation were analyzed theoretically and experimentally. The amplitude and temporal variation of the shock wave pressure was determined basing on a proposed hydrodynamic model of nanosecond laser ablation and experimentally verified with use of a polyvinylidene fluoride (PVDF) piezoelectric-film sensor. The determined pressure wave was used for examination of adhesive strength of tungsten-zirconium-boride coatings on steel substrate. The magnetron sputtered (MS) W-Zr-B coatings show good adhesion to the steel substrate. The obtained experimental results prove the correctness of the proposed model as well as the suitability of the procedure for assessment of adhesive strength.