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 TiO 2 thin films on fluorophlogopite particles. It was found that the effective addition ratio of nano-TiO 2 particles is above 0.2 wt% to realize fluidization of fluorophlogopite particles. The addition of nano-TiO 2 particles leads to competitive deposition between free TiO 2 particles and fluorophlogopite particles, which decreased the coating rate of TiO 2 on fluorophlogopite particle. Besides, the existence of free TiO 2 particles on pearlescent pigment particles decreases the glossiness. The gas-solid ratio primarily determines the number of the free TiO 2 particles on pearlescent pigment particles. It was summarized that the optimal value of addition ratio of nano-TiO 2 is 0.4 wt% with the gas-solid ratio of ∼0.05 m 3 kg −1  h −1 to enhance the fluidization quality on the one hand, and to reduce the free TiO 2 particles on the other hand.