Strategy to boost hydrolysis resistance and stabilize low infrared emissivity of ZrB 2 via nanoscale LaF 3 surface modification

Owing to its excellent high-temperature resistance and high conductivity, zirconium diboride (ZrB 2 ) has been applied as an infrared suppression coating. However, ZrB 2 is susceptible to hydrolysis under high-moisture conditions and even under mild working temperatures. The improvement in the hydrophobicity of the ZrB 2 surface effectively reduces wetting by water and suppresses hydrolysis reaction, particularly under high-temperature and high-moisture conditions. Herein, we report a novel, easy, and highly reproducible method for producing a fully coated ZrB 2 surface by developing a nanoscale hydrophobic layer of glassy LaF 3 on the surface of ZrB 2 powder particles in situ (i.e., during the carbothermal synthesis of ZrB 2 ). Through the tests carried out at 200 °C for 100–300 h in a hydrothermal reactor, the produced powders displayed remarkably high long-term hydrolysis resistance and pronounced chemical stability. Compared with treated ZrB 2 , ZrB 2 @LaF 3 remained lower infrared emissivity when continuously intensifying hydrolyzation process. The results suggest that a nanoscale surface modification strategy can be applied to stabilize the infrared emissivity of ZrB 2 in a water-oxygen coupling environment. Graphical abstract