ZrB2 matrix composites with Cr3+/Nd3+ doped Al2O3 luminescent nanoparticles for non-contact temperature sensing

The effect of the addition of Cr3+/Nd3+ doped Al2O3 nanoparticles (Al2O3 co-doped with 1% Cr3+ and 1% Nd3+ ions) on the mechanical and luminescent properties of ZrB2 ceramic composites was investigated. ZrB2 based composites with addition of 8, 16 and 32 wt.% of alumina nanoparticles were prepared by spark plasma sintering (SPS). Microstructure characteristics were studied by scanning electron microscopy (SEM), elastic modulus by ultrasonic wave transition method, hardness and fracture toughness by the Vickers indentation methods. The addition of alumina nanoparticles had positive effect on the mechanical properties of the composites. Thus, the hardness increased from 14.5 to 16.2 GPa and the fracture toughness from 3.91 to 5.89 MPa.m(1/2) in comparison to the values of the monolithic ZrB2 system. The composite with the highest additive content showed evident luminescent character and the increase of the temperature caused a reduction of luminescent intensity. This is the first report which shows luminescent properties of ZrB2 composites. Moreover, for the first time, luminescent properties of Cr3+ ions were used to develop ZrB2 matrix composites with Cr3+/Nd3+ doped Al2O3 particles with the self-temperature readout functionality via luminescent thermometry.