"Documentary Express" Calcium phosphate can replace zinc phosphate for the preparation of water-based epoxy anti-corrosion coating, and the amount is greatly reduced

keywords:anti-corrosion coating water-based paintbackground:in the water-based epoxy anti-corrosion coating, the contribution of facial fillers to anti-corrosion anti-rust performance is second only to membrane substances, water-based epoxy anti-corrosion anti-rust coating sand fillers should choose a good coverage, chemical inertness, neutral or alkaline, with low oil absorption and better chemical resistance to the face fillersFor example, iron oxide red is an inert pigment, with high chemical stability, used as a physical rust prevention can play a good shielding role, zinc phosphate is an important anti-rust pigment, its rust prevention mechanism is to form a solid complex on the metal surface, at the same time can be with the anti-rust paint hydroxhesy, pyridine, so that the coating and substrate between the formation of chemical binding and improve the coating's adhesion and immunity, SolNRoselli of La Plata National University, and others have studied and prepared a new zinc-free, low phosphate-type water-based epoxy anti-corrosion coating, which is characterized by the addition of calcium phosphate and molybdenum as anti-corrosion anti-rust fillersThe results were published in Progressin Organic Coatings in 2017research content:paint formulation
the author prepared 8 coating formulations, as follows:table 1 water-based anti-corrosion coating formulation
mainly to adjust the amount of calcium phosphate and radon acid addedresults and discussion
1, after adding filler corrosion potential and appearance characterization
The corrosion potential of steel under different fillerscan be seen, adding calcium phosphate, argon can change the corrosion potential of steel, calcium phosphate suspension steel corrosion potential is transferred to negative value due to the formation of phosphate layer, and molybdenum replaced steel corrosion potential as positive value, the corrosion potential of the steel in the two pigment mixtures is the same as the corrosion potential changeFigure 2 is an electro-mirror photo of calcium phosphate and vanadium addedFigure 2 steel surface electric mirror photo(a, add calcium phosphate, b, add molybdenum, c, add calcium phosphate and molybdenum)2, coating anti-corrosion effect
the author of the preparation of 7 coatings for artificial acceleration anti-corrosion test, the results are as follows:table 2 water-based anti-corrosion coating salt Fog performance test
Figure 3 water-based anti-corrosion coating salt spray photocan be seen by Table 2, in addition to 3 s paint, 4300h after other paint salt spray performance is good, 5350h after the salt spray performance of 1, 2, 5 and 7 s paint is still goodThe results show that even if the content of calcium phosphate and molybdenum acid is low, the good effect can be obtained, which shows that the anti-corrosion pigment content can be reduced, and the ideal anti-corrosion and rust-proof effect can be achievedIn terms of coating foaming, it can be seen that 2570h began to foam, but after the comparison, it was found that the coating added to calcium phosphate, molybdenum is less than the unused coating foaming degree, of which 5 and 7 of the paint 5350h before foaming3, the coating of the constant temperature and humidity test
table 3 water-based anti-corrosion coating constant temperature and humidity test
can be seen by table 3, after 1180, 3, 4, 5, 6 and 7 , the anti-rust effect is good, but after 216h began to foam4, other testthe author also through the ion impedance test, paint panel soaked in 0.5M NaCl solution 39 days after the noise test, coating corrosion potential test and so on to prove calcium phosphate and argon acid into the water-based epoxy coating has a good anti-corrosion anti-rust effect, the same anti-corrosion anti-rust effect, the filler use is 1/3 of zinc phosphateconclusion
SolN Roselli et al replaced zinc phosphate with calcium phosphate in water-based epoxy coatings to achieve anti-corrosion and rust protection, and added molybdenum to further improve the anti-corrosion and rust resistance of water-based epoxy coatings In addition, the coating was tested for salt spray, and it was found that calcium phosphate and molybdenum acid were replaced with zinc phosphate as anti-corrosion anti-rust pigments, which not only had excellent anti-corrosion and rust resistance, but also reduced the amount by 2/3 The recommended amount of calcium phosphate is not less than 10% of the amount of facial fillers references: Sol N.Roselli, Gabriela Lendvay-Gy-#246; Gabor M?sz?ros, Cecilia Derik?, Roberto Romagnoli.Antibowabowles freeandandwithsyn.co.g Progressin OrganicCoatings.112 (2017): 27-36.
Writer: Liu Hangong