Multifunctional superhydrophobic and cool coating surfaces of the blue ceramic nanopigments based on the heulandite zeolite

Abstract

The heulandite zeolite was successfully used as the host structure for a new Co-based blue colorant ceramic pigment. The method was the ion exchange of Co and Zn cations with the host structure, which induced a heat-collapsed structure followed by a recrystallization process at 1200 °C/h. The synthesized blue pigment was coated by spraying on the surface of pre-sintered ceramic tile followed by firing at 980 °C/10min. For modification of its surface, ZnO nanoparticles (NPs) and commercial antifouling were used. The blue powder pigment and ceramic coated surface were characterized with XRD, Rietveld refinement, TGA-DTA, FE-SEM-EDS, BET-BJH, UV-VIS-NIR spectroscopy, CIEL*a*b* color measurement, water contact angle (WCA), and roughness analysis. The single-crystal Co-willemite has been achieved (b* = −45 and a* = −0.5). The blue pigment coated on the surface after being modified with ZnO NPs and antifouling revealed a superhydrophobic surface with WCA = 153.7°. Due to this, a low water sliding angle of less than 5° have achieved. The surface showed high thermal stability and adherence. The superhydrophobicity was mainly due to the micro-nanopatterned lotus leaf-like crystal structure and roughness of 3.15 μm on the surface. The surface showed 64% total reflectance from 700 to 2500 nm (UV and NIR), which resulted in a perfect candidate for a cool coating.