In reducing inorganic acid and some organic acids, the corrosion rate of titanium alloy plate is relatively fast because it cannot maintain the passive oxide film. Adding corrosion inhibitor is an effective measure to reduce corrosion. Candle inhibitors include precious metal ions, heavy metal ions, oxidizing inorganic foods, oxidizing organic compounds, complex organic corrosion inhibitors, etc. The price of precious metal ions is very high, and they are rarely used as corrosion inhibitors for reducing organic acids; to metal ions, copper ions and iron ions have very obvious corrosion inhibitors, but they need to reach a critical concentration before they can work; Oxidizing inorganic compounds include nitric acid, chlorine, potassium chlorate, potassium dichromate, potassium permanganate, hydrogen peroxide, etc.; oxidizing organic compounds include nitro or nitroso compounds, nitrogen compounds, etc.; complex organic retarders Corrosion agents are different from oxidizing organic compounds. They can inhibit corrosion at any concentration. There is no concept of critical concentration, but the effect is different.
The surface treatment is an effective way to improve the corrosion resistance of titanium alloy plates. Surface treatment methods include cathodic oxidation, thermal oxidation, nitriding and coating techniques. Anodizing, thermal oxidation and the influence of the Xu layer on the crevice corrosion time of the titanium alloy plate. The data shows that the effect of the coating on the corrosion resistance of the titanium alloy plate is the most obvious, even better than the corrosion resistance of Ti—0.15Pd.
The anodic oxidation of titanium alloy plate is usually carried out in 5%-10%(NH4)2sO solution and 25V direct current voltage is applied. The thickness of the anodic oxide film can reach 300-500nm. Anodizing treatment can effectively remove iron contamination on the surface, effectively prolong the passivation time of the titanium alloy plate, and prevent hydrogen absorption caused by ortho iron contamination. Therefore, foreign regulations require that all titanium equipment must be anodized. In order to improve the effect of anodizing, the anodizing solution uses sodium platinum to replace ammonium sulfate, so that the corrosion resistance is better.
The titanium alloy plate can be oxidized into a rutile-type thermal oxidation strand with a thicker and higher crystallinity than the anodized film in the air, and its corrosion resistance is better than that of the anodized film. The thermally oxidized strands of the titanium alloy plate are made at a temperature of 600-700°C and a time of 10-30 minutes. If the temperature is too high or the time is too long, the effect is not good.
Among the coating layers of the titanium alloy plate, the coating removal effect is the best. The coating containing palladium is usually an oxidation coating or a lead alloy coating. The typical preparation method of palladium oxide coating PdO-T102 is to apply PdCL4 and TiCL3 solution to the surface of the titanium alloy plate and heat it at 500-600℃ for 10-50 min. Repeat the operation several times to make the coating thickness reach 1g /M2 or more. The riveting alloying layer is first deposited by electroplating or vacuum deposition of a very thin layer, and surface alloying treatment techniques such as laser remelting surface or ion implantation are carried out, and its adhesion and corrosion resistance is better than that of the oxide coating.
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