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Electropolymerization of polypyrrole coatings in the presence and absence of sodium nitrate was applied on rheo-cast Al-4.5% Si alloy and pure aluminum. The results showed that the eutectic silicon phase and intermetallic particles in the alloy's microstructure increase the electrodeposition rate in comparison to the pure aluminum substrate. The electrochemical and microstructural studies show that the polypyrrole coatings are able to protect the surface due to the barrier properties and the passivation protection provided by the reduction of the conductive polymer. The coating electrodeposited from sodium nitrate-containing electrolyte presented improved protection for longer immersion time. Localized formation of a thick oxide layer as a result of the drastic galvanic coupling at the polypyrrole/aluminum interface leads to blister formation and failure of the coating. It was revealed that the coating could be deposited into the porosities produced by the casting related defects, but in most cases, this affects the corrosion protection leading to imminent failure.

Electropolymerization of polypyrrole coatings in the presence and absence of sodium nitrate was applied on rheo-cast Al-4.5% Si alloy and pure aluminum. The results showed that the eutectic silicon phase and intermetallic particles in the alloy's microstructure increase the electrodeposition rate in comparison to the pure aluminum substrate. The electrochemical and microstructural studies show that the polypyrrole coatings are able to protect the surface due to the barrier properties and the passivation protection provided by the reduction of the conductive polymer. The coating electrodeposited from sodium nitrate-containing electrolyte presented improved protection for longer immersion time. Localized formation of a thick oxide layer as a result of the drastic galvanic coupling at the polypyrrole/aluminum interface leads to blister formation and failure of the coating. It was revealed that the coating could be deposited into the porosities produced by the casting related defects, but in most cases, this affects the corrosion protection leading to imminent failure.

Electropolymerization of polypyrrole coatings in the presence and absence of sodium nitrate was applied on rheo-cast Al-4.5% Si alloy and pure aluminum. The results showed that the eutectic silicon phase and intermetallic particles in the alloy's microstructure increase the electrodeposition rate in comparison to the pure aluminum substrate. The electrochemical and microstructural studies show that the polypyrrole coatings are able to protect the surface due to the barrier properties and the passivation protection provided by the reduction of the conductive polymer. The coating electrodeposited from sodium nitrate-containing electrolyte presented improved protection for longer immersion time. Localized formation of a thick oxide layer as a result of the drastic galvanic coupling at the polypyrrole/aluminum interface leads to blister formation and failure of the coating. It was revealed that the coating could be deposited into the porosities produced by the casting related defects, but in most cases, this affects the corrosion protection leading to imminent failure.

Electropolymerization of polypyrrole coatings in the presence and absence of sodium nitrate was applied on rheo-cast Al-4.5% Si alloy and pure aluminum. The results showed that the eutectic silicon phase and intermetallic particles in the alloy's microstructure increase the electrodeposition rate in comparison to the pure aluminum substrate. The electrochemical and microstructural studies show that the polypyrrole coatings are able to protect the surface due to the barrier properties and the passivation protection provided by the reduction of the conductive polymer. The coating electrodeposited from sodium nitrate-containing electrolyte presented improved protection for longer immersion time. Localized formation of a thick oxide layer as a result of the drastic galvanic coupling at the polypyrrole/aluminum interface leads to blister formation and failure of the coating. It was revealed that the coating could be deposited into the porosities produced by the casting related defects, but in most cases, this affects the corrosion protection leading to imminent failure.

Effect of solution chemistry on the electropolymerization and the electrochemical properties of polypyrrole coatings on aluminum is studied by means of electrochemical techniques, scanning electron microscopy (SEM), and x-ray photoelectron spectroscopy. It is shown that the protection effect of the coating in long-term exposures and when exposed to more concentrated NaCl solutions depends on the chemistry of electropolymerization electrolyte. The results show that nitrate anions passivate the aluminum substrate during the electropolymerization process. The resulting coating is less prone to blistering in a NaCl solution and probably due to its higher electrochemical activity presents a higher anodic protection effect. The galvanic interaction of polypyrrole coating with aluminum in a NaCl solution is directly observed using focused ion beam-assisted SEM.

Electropolymerization of polypyrrole coatings in the presence and absence of sodium nitrate was applied on rheo-cast Al-4.5% Si alloy and pure aluminum. The results showed that the eutectic silicon phase and intermetallic particles in the alloy's microstructure increase the electrodeposition rate in comparison to the pure aluminum substrate. The electrochemical and microstructural studies show that the polypyrrole coatings are able to protect the surface due to the barrier properties and the passivation protection provided by the reduction of the conductive polymer. The coating electrodeposited from sodium nitrate-containing electrolyte presented improved protection for longer immersion time. Localized formation of a thick oxide layer as a result of the drastic galvanic coupling at the polypyrrole/aluminum interface leads to blister formation and failure of the coating. It was revealed that the coating could be deposited into the porosities produced by the casting related defects, but in most cases, this affects the corrosion protection leading to imminent failure.

Electropolymerization of polypyrrole coatings in the presence and absence of sodium nitrate was applied on rheo-cast Al-4.5% Si alloy and pure aluminum. The results showed that the eutectic silicon phase and intermetallic particles in the alloy's microstructure increase the electrodeposition rate in comparison to the pure aluminum substrate. The electrochemical and microstructural studies show that the polypyrrole coatings are able to protect the surface due to the barrier properties and the passivation protection provided by the reduction of the conductive polymer. The coating electrodeposited from sodium nitrate-containing electrolyte presented improved protection for longer immersion time. Localized formation of a thick oxide layer as a result of the drastic galvanic coupling at the polypyrrole/aluminum interface leads to blister formation and failure of the coating. It was revealed that the coating could be deposited into the porosities produced by the casting related defects, but in most cases, this affects the corrosion protection leading to imminent failure.