The electrochemical catalytic properties of titanium screw coatings mentioned earlier, this is an important application area of ​​titanium screw surface coatings. Titanium itself has excellent corrosion resistance, relatively low price, and high specific strength. A layer of activated metal, usually noble metal or noble metal oxide, is coated on the surface of the titanium screw to become the anode of the titanium activation coating. Titanium screw anodes are widely used in chemical industries such as chlor-alkali, cathodic protection projects, etc., and are used as insoluble anodes.
Platinum-plated titanium screw anodes have been used for many years. Methods for plating platinum on titanium screws include electroplating (molten salt plating) and thermal decomposition, and can also be directly coated, such as explosive recombination. Platinum electroplating is usually carried out in a cyanide molten salt tank. The ratio of cyanide added in the tank is 53% sodium cyanide and 47% potassium cyanide, and the temperature is 520°C. The platinum sheet acts as a soluble anode. The maximum thickness of the coating is 1500um, and the deposition rate is 20-25um/h. The platinum solution is plated with a low deposition rate and a thick coating cannot be obtained.
Aqueous solution silver plating process is simple and easy to operate, but the thickness of the coating-generally not more than 2.5um. If you use extra-pulse plating process, you can get 3-6um thick bright platinum coating. The aqueous solution uses H2Pt(NO2)z2S04, each liter of solution contains platinum 5-10g, the pH value is adjusted to 1.2-2 with sulfuric acid, the temperature is 50℃, the current waveform is cloud wave, the cut-off ratio is 5-9, the average current The density is 50-100A/m2, and the anode is pure platinum. Iridium and platinum coatings on titanium have a very low chloride evolution electricity price in chlorides, and more attention has been paid to the research and application of this titanium screw anode. The Ding Yi method of preparing this kind of Qin electrode by thermal decomposition method is similar to that of the rust-oxide electrode: dissolving the chloride of platinum and iridium in a mixture of butanol and anisole in a volume ratio of 3:1, tI, which is small The precious metal content is 2.13mg/cm3, of which the mass ratio of platinum and iridium is 6:4; this mixed solution is brush-coated on the titanium sample, dried and heated to form a film at 500°C. This needs to be repeated many times until the required thickness is reached. The thickness is usually controlled at about 20g/m2.
The most common application of titanium screw anodes is Ru02-T102 and Ru02-IrO2-TiO2 coatings. The electrode life depends on the use environment and current density. The general trend is that the life is constantly increasing. The research on the activated oxide deposit of titanium screws is still evolving. Continue to change the composition of the Xu layer. The thermal oxidation process can further improve the electrochemical performance and service life of the Xu layer.