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Activated Anode Coating for Titanium Screws

The electrochemical catalytic performance of titanium screw coatings was mentioned earlier, which is an important application field of titanium screw surface coatings. Titanium itself has excellent corrosion resistance, relatively low price, and high specific strength. A layer of activated metal, usually precious metal or precious metal oxide, is coated on the surface of titanium screws to become the anode of the titanium activation coating. Titanium screw anodes are widely used in chemical industries such as chlor alkali and cathodic protection engineering, as insoluble anodes.
Platinum plated titanium screw anodes have a long history of use. The methods for plating platinum on titanium screws include electroplating (molten salt plating) and thermal decomposition, as well as direct coating, such as explosive bonding. Platinum plating is usually carried out in a cyanide molten salt bath, with a cyanide ratio of 53% sodium cyanide and 47% potassium cyanide added to the bath at a temperature of 520 ℃. Platinum sheets serve as soluble anodes. The maximum thickness of the coating is 1500um, and the deposition rate is 20-25um/h. Platinum plating in aqueous solution has a low deposition rate and cannot obtain a thicker coating.
The silver plating process in aqueous solution is simple and easy to operate, but the coating thickness generally cannot exceed 2.5um. If an out of pulse electroplating process is used, a bright platinum coating with a thickness of 3-6um can be obtained. The aqueous solution uses H2Pt (NO2) z2S04, with a platinum content of 5-10g per liter. The pH value is adjusted to 1.2-2 with sulfuric acid, the temperature is 50 ℃, the current waveform is cloud wave, the break to break ratio is 5-9, the average current density is 50-100A/m2, and the anode is pure platinum. Iridium and platinum coatings on titanium have a low chlorine evolution electricity price in chlorides, and the research and application of this titanium screw anode have received more attention. The process of preparing this type of Qin electrode using thermal decomposition method is similar to that of preparing rust oxide electrode: the chloride of platinum and iridium is dissolved in a mixture of butanol and benzyl ether with a volume ratio of 3:1, with a small noble metal content of 2.13mg/cm3. The mass ratio of platinum and iridium is 6:4; Brush this mixture onto the titanium sample, dry it, and heat it to form a film at 500 ℃. This process needs to be repeated multiple times until the required thickness is achieved, usually controlled at around 20g/m2.
The most commonly used titanium screw anodes are Ru02-T102 and Ru02-IrO2-TiO2 coatings. The electrode lifespan depends on the usage environment and current density, and the overall trend is that the lifespan is constantly increasing. The research on the activation and oxidation of titanium screws is still evolving, and changing the composition of the oxide layer and the thermal oxidation process can further improve the electrochemical performance and service life of the oxide layer.

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