Will the Impurities Cause Titanium Dioxide Discoloration by Heat?
If the titanium dioxide contains iron oxide, nickel oxide, chromium oxide and other such impurities, after the sunlight will become brown, after leaving the sun can return to the original color; in the process of oxygen, titanium dioxide heated to 200 ℃ -600 ℃, titanium dioxide will become flower brown, after cooling will return to the original color, this phenomenon is known as the phenomenon of photochromic interchange.
The main reason for this phenomenon is the photochemical nature of titanium dioxide. Titanium white in the light of daylight love, will absorb the oxygen released by the ultraviolet light below 400nm, will make these impurities, the formation of oxides, stop irradiation after the titanium white will return to its original color.
The performance of titanium white is closely related to photochemistry, and titanium white is a specific expression of optics, titanium white as the * basic pigment properties such as whiteness, hiding power, achromatic power, weatherability, are the result of the role of optics. Titanium white * outstanding pigment properties is to have a relatively strong covering power, he is a pigment can cover the surface of the object to be painted the ability to achieve complete coverage, unit weight of paint can cover the substrate area, can achieve complete coverage of the amount of paint required.
The main factors affecting its covering power are the refractive index of the pigment crystal itself, its particle size and its particle size distribution and its dispersion performance, of which the optical nature is caused by the difference of refractive index of the surrounding medium.
