Olha P. Khlopyk

Композиційний протикорозійний пігмент отримано методом твердофазного модифікування у високоенергетичному планетарному млині шляхом механохімічної взаємодії природного силікату (воластоніту) із цинку монофосфатом. Морфологію та фазовий склад пігменту досліджено методами сканувальної електронної мікроскопії та Х-променевого фазового аналізу, які підтвердили утворення аморфної фосфатної фази на поверхні воластоніту. Методом електрохімічної імпедансної спектроскопії встановлено, що композиційний пігмент ефективно інгібує корозію алюмінієвого сплаву Д16Т у хлоридному середовищі, що виявляється у підвищенні модуля імпедансу приблизно у 15 разів порівняно з неінгібованим середовищем та у 5 разів порівняно з простою сумішшю вихідних компонентів, а також супроводжується збільшенням опору перенесення заряду і формуванням щільної захисної плівки. Захисна дія зумовлена формуванням на поверхні сплаву щільної та рівномірної плівки, що містить фосфати кальцію, цинку та алюмінію.

The inhibitory effect of a composition based on dextrin and zinc gluconate on the corrosion of D16T (AA2024) aluminium alloy in a 3% NaCl solution following mechanical surface activation was investigated using polarization and impedance spectroscopy. Repassivation of the fresh surface was observed, and an increase in the alloy corrosion resistance in the inhibited environment was established. An increase in charge transfer resistance, a decrease in corrosion current density and a high degree of protection were recorded as a result of formation of a dense protective film with pronounced barrier properties on the metal surface and enhanced repassivation following mechanical fracture of the passive layer. An inhibition mechanism was proposed, associated with the formation of a complex structure “dextrin–zinc gluconate–Al3+ which blocked active sites and inhibited the penetration of chloride ions. The investigated composition may be promising for the protection of aluminium alloys against tribocorrosion in high-salt environments.

The protective efficiency of an environmentally safe composition based on sodium alginate and zinc acetate was investigated during the repassivation stage of the mechanically activated surface of D16T aluminum alloy. It was established that the use of the composition in a 0.1% NaCl solution promoted restoration of the electrode potential and reduced the corrosion current density of the alloy within the first minute by a factor of 2 compared to the uninhibited solution. Micro-X-ray spectral analysis and FTIR spectro­scopy confirmed the formation of a protective film containing alginate complexes with Al3+ and Zn2+ cations.The obtained results indicate the prespective use of this composition for protecting aluminum alloy structures operating under conditions of corrosion-mechanical loading.

The results of a study on the anticorrosion properties of a composite pigment based on calcium silicate and zinc orthophosphate, obtained by solid-phase modification in a high-energy planetary ball mill are presented. X-ray energy-dispersive analysis confirmed the presence of silicon, phosphorus, calcium, and zinc in the pigment composition. Electrochemical impedance spectroscopy revealed that introduction of the composite pigment into an epoxy coating on an aluminum alloy significantly enhances its protective properties, particularly under conditions of localized coating damage. The synergistic interaction between the pigment components promotes the formation of a stable protective layer in defect zones, effectively inhibiting the corrosion process. The highest anticorrosion efficiency was observed for the pigment with a wollastonite-to-zinc orthophosphate mass ratio of 2:3, which provided reliable protection for both damaged and intact epoxy coatings during exposure to a 0.1% NaCl solution. The results indicate that the composite pigment stabilizes the barrier properties of the coating and reduces the degradation of the paint system.

The inhibitory effect of compositions based on sodium alginate and zinc salts on the alu­minum alloy corrosion in a chloride-containing environment was studied. It was found that the protective effectiveness largely depends on the nature of the anion in the zinc salt composition. The mechanisms of the formation of protective films on the alloy surface were characterized based on the results of electrochemical measurements, electron microscopy and energy-dispersive X-ray microanalysis. The highest corrosion resistance (96%) was demonstrated by the composition with zinc acetate, which is due to the formation of a homogeneous film with high charge transfer resistance. The composition based on zinc nitrate provided protection at the level of 93% due to surface passivation and the formation of an oxide layer. The lowest efficiency (82–83%) was shown by the composition with zinc sulfate, which is associated with the formation of less stable sorption structures.

A composite inhibiting pigment based on natural calcium silicateand zinc monophosphate was obtained by mechanochemical modification. Pigment extracts reduce the corrosion current density and increase the resistance to charge transfer of carbon steel in the slightly acidic atmospheric precipitations due to the formation of a protective film on its surface. The presence of phosphorus, zinc, and calcium was found in the composition of this film, which indicates the formation of phosphates. Adding a composite pigment to the priming layer of the alkyd coating significantly increases its corrosion resistance compared to the uninhibited sample. The obtained composite pigment has increased protective properties in the slightly acidic atmospheric precipitations and is promising for use in paint coatings on carbon steels.