Effects of nano-TiO2 particles addition on fluidization of flaky fluorophlogopite powder for the CVD preparation of pearlescent pigments

The fluidization quality significantly affects the mass transfer and the deposition reaction, which determine the uniformity of deposited TiO2 thin films on fluorophlogopite particles. It was found that the effective addition ratio of nano-TiO2 particles is above 0.2 wt% to realize fluidization of fluorophlogopite particles. The addition of nano-TiO2 particles leads to competitive deposition between free TiO2 particles and fluorophlogopite particles, which decreased the coating rate of TiO2 on fluorophlogopite particle. Besides, the existence of free TiO2 particles on pearlescent pigment particles decreases the glossiness. The gas-solid ratio primarily determines the number of the free TiO2 particles on pearlescent pigment particles. It was summarized that the optimal value of addition ratio of nano-TiO2 is 0.4 wt% with the gas-solid ratio of ∼0.05 m3kg−1 h−1 to enhance the fluidization quality on the one hand, and to reduce the free TiO2 particles on the other hand.