Correlation between laser spectroscopic studies and mechanical characterization of zirconia-based multiwall carbon nanotube ceramic composites

The hardness of zirconium oxide-based ceramic nanocomposites was correlated with the laser spectroscopic studies by analyzing the samples through nanosecond and femtosecond laser to see the viability of this technique as a fast and in situ for assessment of mechanical properties in nuclear industry. Zirconia incorporated with different vol% of multiwall carbon nanotubes were processed by the high frequency induction heated sintering. The composites were characterized by the nanosecond laser-induced breakdown spectroscopy (LIBS) with optimized delay time of 1, 2, and 3 µs and 200 and 300 mJ energies generated by laser Nd:YAG (λ = 1064 nm). The plasma temperature resulted by the ablation of different samples was estimated through intensity of selected zirconium lines using the Boltzmann plot method. The samples were mechanically characterized by the Vickers hardness test. The estimated plasma temperature and the ratio of Zr(II) with different intensities of Zr(I) emission lines show rather weak dependency and increase with surface hardness. The samples were scrutinized by the femtosecond laser micromachining through variation in depth and surface morphology of machined areas. It is found that deeper circular groove and enhanced erosion of disk shape by femtosecond laser machining are achieved for less hard materials and are in agreement with the LIBS analysis.