Enhanced high temperature oxidization resistance of silica coated γ-Ce2S3 red pigments

Silica layer coated gamma-Ce2S3 red pigments were successfully prepared based on a Stober method followed by a hydrogen-argon atmosphere heat treatment at 700 C. The effect of water/ethanol volume ratio and tetraethoxysilane concentration on the microstructure of the coating layer and its high temperature oxidizing protection to pigments was investigated. A transparent silica coating layer with dense microstructure and about 60 nm thickness can provide a favorable protection for the red hue of the gamma Ce2S3 pigments. The oxidization resistant temperature was enhanced to 550 C for the dense silica layer coated gamma-Ce2S3 pigments as compared to <350 C for the uncoated ones. A red color (L* = 29.59, a* = 27.53 and b*= 27.66) was still remained for such silica coated gamma-Ce2S3 pigments after heated treated at 550 C in air, indicating its potential for high temperature industrial applications. (C) 2016 Elsevier B.V. All rights reserved.