Application of Laser-Ultrasound for Characterization of Plasma-Sprayed Ceramics

Laser-based resonant ultrasound spectroscopy (RUS) method was applied to measure elastic constants of a porous calcium titanate coating manufactured by water-stabilized plasma-spraying (WSP). To enhance the reflectivity of the polished surface of this material for the lasers applied at RUS measurements, a thin coating of sodium metasilicate (waterglass) was used. It is discussed how the metasilicate affects the acoustic properties of the underlying porous material and experimentally shown that such a surface treatment enables the characterization of the structural processes in these materials at elevated temperatures.