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|EINECS No.:||237-714-9||Molecular weight:||311.8989|
Anti-rust effect of aluminum tripolyphosphate in solution with different pH values
Aluminum tripolyphosphate can release tripolyphosphate ions (P3O105-) with strong chelating ability. It has a high chelating ability for divalent and trivalent iron ions, forming the main body of iron tripolyphosphate. Complex protective film. This phosphate protective film is difficult to dissolve in water, has high hardness, and has strong adhesion to the substrate metal. It can provide excellent corrosion protection even in the most rusty metal cutting parts; on the other hand, coating The aluminum tripolyphosphate in the membrane reacts with the penetrating water to depolymerize and transform into low-molecular compounds and orthophosphate. The active phosphate ions generated during the depolymerization process can also phosphatize and passivate the surface of the steel metal again. Produce the same excellent passivation protective film. The response is as follows:
Aluminum tripolyphosphate has different application effects in different pH solutions. Under acidic conditions, it is beneficial to the stability of P3O105-, but at the same time there is also the corrosion reaction of H+ on the iron base, and the corrosion reaction speed is greater than the film formation rate of P3O105- on the iron base, so the iron base cannot be effective for a long time. protection. Alkaline conditions are conducive to the stability of PO43-, and the formed ferrous phosphate (ferrous) passivation film is far less powerful than that of ferrous tripolyphosphate (ferrous), and the effective (covered) area is also smaller. At the same time, there is a competitive reaction of OH-corrosion to iron, so the iron base cannot be effectively protected for a long time.
3.Aluminium tripolyphosphate dihydrogen Quality standard:
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