Experimental and theoretical modeling study on the infrared properties of ZrB2 thin film

Abstract Surface oxidation and deterioration of mechanical properties in high-temperature environment have hamperd application of low infrared emissivity materials. Zirconium diboride (ZrB2) exhibits excellent thermal stability and electrical conductivity due to the combination of properties of ceramics and metallic materials, which is promising for application as low infrared emissivity material in high-temperature environment. In this work, we demonstrate the deposition of ZrB2 thin films with different thicknesses, varying from 20 nm to 600 nm, on Si (111) and ZnS substrates by direct current magnetron sputtering method. Infrared emissivity characterization is carried out in the range of 3 to 14 μm, whereas thickness dependence is elaborated in terms of crystal structure, surface roughness and electrical conductivity. Experimental results reveal that normal infrared emissivity of ZrB2 films decreases with an increase in film thickness, from 100 nm to 400 nm, due to influence of substrate, surface roughness and electrical conductivity. The relationship among surface roughness, electrical conductivity and infrared emissivity is theoretically illustrated in detail.