Thermal stability and optical properties of single-layer nano-composite TiN/TiC-Ni/Mo solar-selective-absorbing coatings by laser cladding

Currently, the most important challenge for solar energy photo-thermal utilization is the thermal stability of solar absorber coatings at high temperature. The new one-layer nano-composite TiN/TiC-based cermet coatings were designed and fabricated with laser-cladding method in the air. The result indicated the laser cladding could be used to obtain 30 wt.%, TiN-30 wt.%, TiC-20 wt.%, and Ni-20 wt.% Mo cermet coatings with the desired optical properties. In particular, an absorptance (α) of ~80.1% and a thermal emissivity (ε) of ~2% at 300 K were calculated when the weight rate of nano-particles/micro-particles is 1:1. In addition, the thermal stability of the coating was outstanding after heat treatment at 650 °C for 6 h. The absorptance and emissivity of cermet coating were, respectively, 80.8% and 1.9% at 650 °C. The results indicated that nano-composite TiN/TiC-Ni/Mo cermets are suitable for spectrally selective materials. Moreover, the laser cladding was found to be an improved and novel preparation method in the field of solar-selective-absorbing coatings.