Titanium is a precious metal, and its relative density is small, high strength, and high specific strength. Next, I will introduce the corrosion resistance properties of titanium and titanium plate materials, I know the titanium pump, the occasion and function of the titanium plate pump can be used. It has excellent corrosion resistance in a specific environment. Titanium pump, titanium plate pump is a kind of strong corrosion-resistant pump, suitable for strong base and strong acid, so it is also called strong base and strong acid pump. The key to its strong corrosion resistance is titanium, a metal material.
After CNC machining, titanium can be alloyed to greatly increase its strength (TC4 is the most widely used).
Corrosion resistance of titanium and titanium plates Titanium has a high degree of stability in neutral or weakly acidic oxide solutions, for example, titanium and titanium plates in 100 ℃ FeCl100 ℃ CuC12, 100 ℃ HgC1: (all concentrations ), 60% AlCl2 and all concentrations of NaCl at 100 ° C are stable. The oxides of many other metals of titanium are also stable in 100% monooxyacetic acid and 100% dioxyacetic acid, thus making titanium and Titanium plate has been widely used in the above solution.
Titanium and titanium plates have high corrosion resistance in gasoline, toluene, phenol, formaldehyde, trichloroethane, acetic acid, citric acid, monochloroethane, etc. However, in the case of boiling point and no gas, titanium is Formic acid with a mass fraction of less than 25% will be severely corroded. In a solution containing acetic anhydride, titanium is not only severely corroded, but also will cause pitting corrosion. In the production of propylene oxide, phenol, acetone, chloroacetic acid and other chemical media, the corrosion resistance of titanium and titanium plates is better than that of stainless steel and other structural materials.
Titanium and titanium plates are also highly stable to ion-containing oxidant solutions, such as 100qC sodium hypochlorite solution, oxygen water, gas (up to 75 ℃), sodium oxide solution containing hydrogen peroxide, etc. The corrosion resistance of titanium and titanium plates in wet chlorine gas exceeds that of other commonly used metals. This is because chlorine has a strong oxidation effect. Titanium and titanium plates can be in a stable passive state in wet chlorine. In order to maintain the passiveness of titanium in chlorine gas Sexuality requires a certain amount of water. The critical water content is related to oxygen pressure, flow rate, temperature and other factors, as well as the shape and size of titanium equipment or parts and the degree of mechanical damage to the titanium surface. Therefore, the critical water content of titanium passivation in oxygen in the literature is inconsistent It is generally believed that a mass fraction of 0.01% to 0.05% can be used as the critical moisture content of titanium in oxygen, but practical experience points out that in order to ensure the safe use of titanium equipment in oxygen, sometimes the water mass fraction is 0.6% is not enough, it needs to be up to 1.5%. The critical water content also increases as the temperature of the chlorine gas increases and the gas flow rate decreases.
The actual operating experience also shows that after the surface oxide film of the titanium and titanium plate is damaged, a higher water content is required to re-passivate the titanium and titanium plate. Titanium and titanium plates in dry chlorine gas, even below 0 ℃, will react violently to generate titanium tetrachloride with fire hazard. Once the destruction of titanium and titanium plates in dry chlorine gas started, the reaction was collapsed, and the addition of water could not prevent the reaction from proceeding.
The behavior of titanium in the dry and wet boundary areas of chlorine has not been fully clarified. According to thermodynamic analysis, titanium and chlorine cannot exist in an equilibrium state at room temperature. According to thermodynamic free energy, it can be seen that the stable compound titanium tetrachloride is generated in this reaction system If it does not coexist with water, it will react further, namely
TiC14 + 4H20. Ti (OH) + 4HC1
Therefore, the reaction between chlorine and titanium can be explained simply: the reaction of titanium and chlorine will produce titanium tetrachloride: titanium tetrachloride is a liquid at room temperature, and its boiling point is 136. C, the reaction to generate titanium tetrachloride is accompanied by an exothermic process. If the chlorine gas is in a dry state, a large amount of heat is released to make the reaction reach a very high temperature. When the temperature reaches the melting point of titanium, titanium begins to burn. Thereafter, as long as there is enough chlorine, the reaction will proceed vigorously until the reactants are exhausted. However, if there is enough water in the chlorine gas, titanium tetrachloride will react with water to generate titanium hydroxide, which is a non-volatile substance, and becomes a film firmly attached to the surface of titanium, this reaction is extremely Stable reaction, and the surface film is extremely stable in wet chlorine. Therefore, titanium has excellent corrosion resistance in wet chlorine, and its stability is closely related to the water content in chlorine gas.
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