Dispersity of TiO2/SiO2 systems in aqueous suspensions

The dispersity of TiO2/SiO2 systems synthesized by pyrogenic and CVD proces ses was investigated. The dispersity of the TiO2/SiO2 system prepared by th e CVD process was shown to be higher than that of the system obtained by th e pyrogenic process. A bimodal particle size distribution is typical of bot h the systems. The total increase in dispersity of the pyrogenic system at TiO2 content C-TiO2 less than or equal to 20 wt % is caused by a decrease i n the average size of agglomerates only, and at 20 wt % less than or equal to C-TiO2 less than or equal to 36 wt % it results from a decrease in the a verage size of titania-silica (TS) particle aggregates only. The dispersity of the TiO2/SiO2 system obtained by the CVD process depends on the ratio b etween the numbers of TS particle aggregates and agglomerates in the suspen sion beginning with C-TiO2 greater than or equal to 2.8 wt %. Monomodal TS particle distribution for highly dispersed nonporous TiO2/SiO2 systems can be achieved only by the CVD process at C-TiO2 less than or equal to 30 wt % .