Investigation of corrosion causes and failures in the interior metal components of an automobile

The extent of corrosion and the underlying causes of damage to the interior metal components of a one-year-old automobile from a known brand, owned by a rental car company in Serbia, were investigated. The vehicle?s interior, including upholstery and carpeting, showed no chemical spills or other damage. The solution obtained after rinsing a carpet sample from the car floor exhibited neutral pH. The corrosion behavior of the analyzed samples was determined using electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) and linear sweep voltammetry (LSV, Tafel method). X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) analyses showed that corrosion products taken from corroded steel parts contain akaganeite ?-FeO(OH) and iron (II) chloride. FTIR analysis of the organic coating revealed that the applied epoxy layer was insufficiently crosslinked, making it permeable to moisture and chloride ions. Electrochemical corrosion measurements on steel with a similar chemical composition demonstrated an increased corrosion rate in a solution containing dissolved corrosion products compared to a reference solution. This accelerated corrosion was attributed to the acidity of akaganeite and iron (II) chloride, formed due to the vehicle?s exposure to a humid and chloride-rich environment.