Fortification performance of polyurethane coating in outdoor historical ironworks

Abstract

Abstract Background Ironworks in the tomb of Suleiman Pasha Al-Faransawi (located in the old Cairo, Egypt) were exposed in the open-air are susceptible to various corrosion factors, which be contingent on the environmental conditions wherein the artifacts are displayed and the existence of a protective layer or not. Examinations and analysis were conducted to identify the structure and type of the alloys used in making the decorative ironworks, to identify the manufacturing technique and decoration, and to study the nature of rust compounds. This has been achieved by using metallographic microscopy, X-ray diffraction, and a carbon–sulfur analyzer. Many protection approaches have been worked such as varnishes, waxes, and oils, but they have had many disadvantages. The aim of this paper is to assess the competence of polyurethane coating by using electrochemical measurements (electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization) in the fortification of ironworks exposed in the outdoor environment. Results The results confirmed that the decorative ironworks were manufactured from wrought and gray cast iron. The main corrosion products identified by XRD are goethite, akageneite, and maghemite. Lead oxide hydrate refers to old lead paints (red primer) which have been applied to protect the ironworks. Quartz and calcite are the products of heavy dust particles that covered the surface. Conclusion The data proved that the polyurethane is acting as a good protective coating for the decorative ironworks exposed in an uncontrolled environment. The 2% is considered as the recommended dose for this polymer for the minimum corrosion rate of the ironworks.