Mechanical Grinding Preparation and Characterization of TiO2-Coated Wollastonite Composite Pigments

TiO₂-coated wollastonite composite pigments were prepared by the mechano-chemical grinding of wollastonite and TiO₂ powder together in a wet ultrafine stirred mill. X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and infrared spectra were used to investigate the microstructures and morphologies of the composite and the reaction mechanism. The results indicate that the TiO₂-coated wollastonite composite pigments have similar properties to titanium dioxide pigment, showing much better properties than dry and wet mixing of wollastonite and TiO₂. The hiding power of TiO₂-coated wollastonite composite pigments (45% TiO₂) is 17.97 g/m², reaching 81.08% of titanium dioxide. A firm combination between wollastonite and TiO₂ is obtained through a surface dehydroxylation reaction during the mechano-chemical method.