Chemical Durability of Synthesized Sphene

The chemical durability of synthesized sphene, using CaCO₃, TiO₂ and H₂SiO₃ as raw materials by solid-state reaction, was researched by means of X-ray diffraction (XRD), scanning electron microscope (SEM） and atom absorbing spectrum (AAS). The results indicate that the synthesized sphene has a good chemical durability in the aqueous solution whose pH value is 5-9, the temperature and pH of the solution have important influences to its chemical durability in 1-21 days. The nominalized leach rate of Ca²⁺ (42 d) is higher than Ti⁴⁺ about 2 orders of magnitude. When the pH is 7 at 90 ℃, the nominalized leaching rate of Ca²⁺(42 d) and Ti⁴⁺ (42 d) are 3.33×10^-3 and 1.33×10^-5 g•m^-2 •d^-1, respectively. When the pH is 7 at 25 ℃, the nominalized leach rate of Ca²⁺(42 d) and Ti⁴⁺ (42 d) are 1.52×10^-3 and 3.05×10^-5 g•m^-2 •d^-1, respectively. The nominalized leach rate of Ca²⁺ (42 d) is 7.71×10^-2g•m^-2•d^-1, when the pH is 3 at 25 ℃.