Synthesis and chromatic properties of zircon encapsulated ceramic black pigment with carbon sphere as carbon source

The CSs@ZrSiO4 black inclusion pigments were prepared by calcining the precursor formed by the precipitation of Si4+ and Zr4+ on the surface of carbon spheres (CSs), which were synthesized from glucose by hydrothermal process. The as-prepared CSs were amorphous and had plenty of rich oxygen-containing functional groups on their surface with negative charges, which endows the CSs the ability to disperse well in the precursor solution. The amorphous carbon source was carbonized as colorant, which was coated by zircon phase at 1050 degrees C for 2 h in Ar. The results indicated that a dense zirconium silicate coating layer was formed with high encapsulation rate, which protects the inner CSs from oxidation, and enabling the pigment to achieve a deep black hue, as CIE coordination L* = 22.21, a* = 0.14, b* = 2.43 consequently. When the as-prepared inclusion pigment was applied to the transparent glaze at 1100 degrees C, it showed a good chromaticity.