Laser etching of Thoria pellets for microstructural investigations

Metallographic investigation of the microstructure of sintered Thoria pellets necessitates appropriate surface preparation of these pellets. Conventional etching methods involving either chemical or thermal etching techniques being unsuitable for surface etching of irradiated Thoria fuel, laser-based surface treatment was envisaged as a potential alternative technique. Thoria pellets were subjected to laser surface treatment using a pulsed Nd:YAG laser.Our preliminary studies have successfully demonstrated laser etching of sintered Thoria pellets with good reproducibility, clearly revealing grain structures and well-defined grain boundaries. Detailed parametric investigations determining optimum laser parameters for the process, are presented. Our results on ultra-short laser-based etching of sintered Thoria pellets are also discussed.