Influence of activation treatment with nickel acetate on the zinc phosphate coating formation and corrosion resistance

Abstract

Zinc phosphating is a chemical conversion process that has been widely used in industry for corrosion protection and primer for painting. In this investigation, the effect of activation treatment with nickel acetate on the microstructural evolution and corrosion resistance of the zinc phosphate coating on mild steel was studied. The chemical composition and morphology of the coatings were analyzed via scanning electron microscopy (SEM) and energy‐dispersive spectroscopy (EDS). The corrosion resistance of the coatings was evaluated using polarization curves and electrochemical impedance spectroscopy (EIS) in an aerated 3.5% NaCl solution. Surface morphology observations revealed that the activation treatment increased the population density and refined the grain size of the coating. The electrochemical results showed better barrier protection characteristics and corrosion resistance for activated phosphate coatings compared with inactivated coatings.

Ultrasonic Induced Rapid Formation and Crystal Refinement of Chemical Conversed Hopeite Coating on Titanium

“…XRD patterns (Figure ) show that the conversion coatings observed in Figure are hopeite, and it has been corroborated by FTIR spectra presented in Figure . The hopeite crystals are granular with different dimension sizes, and they assembled tightly (Figure e–h), which is different from loose aggregation of isolated crystals on Ti and mild steel. , …”

“…The hopeite crystals are granular with different dimension sizes, and they assembled tightly (Figure 3e−h), which is different from loose aggregation of isolated crystals on Ti and mild steel. 15,18 From Figure 3e−h, it can also be clearly seen that the coatings formed with UI have a crystal size of about 5−20 μm, which is obviously smaller than that in the coatings formed without UI, with a crystal size of about 50−100 μm. At the same time, plenty of crystallites are found on UI treated coatings.…”

Phosphate-doped polyaniline/Al2O3 nanocomposite coating for protection of stainless steel

“…The PANI nanocomposite generally displayed lower C coat values than PANI, which may be attributed to the physical and smart properties of the coatings, including physical prevention and protective layer formation because of iron phosphate complex formation on SS (Kouisni et al , 2005; Kalendová et al , 2014; Abdalla et al , 2014; da Silva et al , 2007), in addition to the blocking effect of adhesive Al 2 O 3 nanoparticles and passive oxide layer. The lower values of C dl for PANI-Al 2 O 3 -doped phosphate coating provided further support of the protection of SS provided by PANI coating in the presence of Al 2 O 3 nano particles.…”

Immersion Behavior of Carbon Steel, Phosphate Carbon Steel and Phosphate and Painted Carbon Steel in Saltwater

“…According to previous studies [ 15 , 16 , 17 , 18 ], phosphating is one of the most widely used methods of protection against corrosion in metals [ 19 ]. The phosphating process consists of, with the help of a phosphating solution, a layer of zinc, iron, or manganese phosphate (depending on the major constituent of the phosphating solution) on the surface of the metal [ 20 ].…”