Papers by Keyword: TiO₂ Coatings

Abstract: Common glass for architecture had only one function, i.e., transparency and the requirement for indoor health made “environmental protection type” novel glass necessary. In the present study, a novel self-cleaning glass was prepared by sol-gel method. To form self-cleaning glass, common glass was adopted as the foundation base and TiO2 coatings were cover its outside surfaces. The novel glass had little change in shape but alteration to slightly white compared to common glass, thanks to white TiO2. The self-cleaning glass could reduce formaldehyde concentration of air from more than 160 mg•m3 to 0.4 mg•m3 within 60 h, while the common glass could cut down to ca. 30 mg•m3 and reaching equilibrium before 24 h. The removal of formaldehyde by common glass could be owing to adsorption action and slightly gradation by ultraviolet light, and the removal by self-cleaning glass could be mostly assigned to photodegradation by TiO2 when ultraviolet light irradiation. Besides, the self-cleaning glass exhibit 74.99% and 91.60% anti-bacteria rate to Escherichia coli and Staphylococcus aureus, respectively, when common glass was chosen as control. In brief, the self-cleaning glass was proved excellent to remove formaldehyde and inhibit bacteria. As a result of the non-preference of the photodegradtion and anti-bacteria by TiO2, it was believed the self-cleaning glass could remove almost all the kinds of indoor organic gases and inhibit almost all the kinds of bacteria, including some pathogens. The self-cleaning glass had great potential in interior finish application meeting the challenge for environmental protection.

Abstract: A series of lanthanum ion-doped titanium dioxide coatings have been prepared on the surface of 304 stainless steel by using sol-gel and dip-coating technology. The corrosion protection properties of the coatings were investigated by electrochemical measurements. It is found that the photogenerated cathodic protection property of the TiO₂ coating is enhanced under illumination by doping with an appropriate amount of lanthanum ions. The results also indicate that the presence of lanthanum ions improves the corrosion protection property of the TiO₂ coating without the photo effect attributed to the self-healing properties of lanthanum ions.

Abstract: The sliding wear property of plasma sprayed TiO2 coatings with porosity of 4.2% and 5.4% mating against silicon nitride ball were comparatively investigated with a reciprocating tribometer under dry conditions. The results indicate that the wear resistance of the TiO2 coating with lower porosity is superior, which is attributed to its homogeneous microstructure and improved microhardness. The morphologies of the wear tracks of the two TiO2 coatings, as well as wear debris reveal the pore is the main location wear occur. The coefficients of friction of the two TiO2 coatings decrease with the increase of applied load, while the wear rates increase, which is attributed to the difference of the dependence of microhardness on load between the coating and the Si3N4 ball. No apparent dependence of wear resistance on sliding speed was found on these two coatings.

Abstract: A TiO2 coating when directly applied on copper plate showed an instantaneous ptype behavior, i.e. ennoblement of electrode potential on ultraviolet (UV) illumination though a copper plate when galvanically coupled to an ITO glass coated with TiO2 showed immediate lowering of electrode potential (‘n’-type effect) on illumination under deaerated conditions. The instantaneous p-type effect in the former case was attributed to the presence of a copper oxide layer present between the copper plate and the TiO2 coating. However, a prolonged exposure of the TiO2 coated copper plate showed an n-type effect under illumination after nearly 24 h, following which the electrode potential appeared stable and highly negative. This observation indicated that the photogenerated electrons in TiO2 are capable of reducing the copper oxide layer to ultimately realize the n-type effect of TiO2. The n-type effect could not be observed in aerated electrolyte solutions. The effect of different conditions in the ambience on the photoeffect of copper coated TiO2 will be discussed.