Analyze the corrosion resistance of titanium pipes!
Generally speaking, titanium tubes are the preferred metal material for nitric acid solution heating equipment. Baoji titanium tube has good corrosion resistance in oxidizing media (such as nitric acid, chromic acid, Hypochlorous acid and Perchloric acid). In reducing acids, the addition of heavy metal salts can have a significant corrosion inhibition effect. Titanium palladium alloy and titanium nickel molybdenum alloy have significantly improved corrosion resistance compared to industrial pure titanium.
In reducing acids (such as dilute sulfuric acid solution, hydrochloric acid solution, etc.), due to the destruction of the passivation of the oxide film, the corrosion rate is relatively fast, and increases with the increase of temperature and concentration. The titanium heat exchanger withstands 60% nitric acid at around 193 ℃ and has not been found to corrode for many years of use. In boiling 40% and 68% nitric acid, there was some corrosion at the beginning. After a short period of time, the passivity of titanium recovered and the corrosion rate significantly decreased. It may be related to the corrosion inhibition effect of titanium ions.
If the temperature is high enough for the solution to boil, even if the sulfuric acid temperature drops to 0.5%, it will still corrode. At the same temperature, when nitrogen is introduced into a sulfuric acid solution, the corrosion rate of titanium is significantly faster than when air is introduced. This corrosion law is basically the same in other reducing Mineral acid. In room temperature sulfuric acid with air flow, industrial pure titanium can only withstand sulfuric acid solutions below 5%; If the temperature drops to around 0 ℃, the sulfuric acid concentration can be increased to 20%.
Titanium alloy is mainly used for making aircraft engine compressor components, followed by structural components for rockets, missiles, and high-speed aircraft. In the mid-1960s, titanium and its alloys were used in general industry, such as making electrodes for electrolysis industry, condensers for power stations, heaters for petroleum refining and seawater desalination, and Waste minimisation devices. Titanium and its alloys have become a corrosion-resistant structural material. In addition, it is also used for the production of hydrogen storage materials and shape memory alloys.
