This report gives an outline of corrosion and anticorrosion issues in relation to building and building equipment. There are two types of corrosion. One spoils the beauty of the building, and the other spoils function of the building. Corrosion, which spoils the beauty, is usually induced by the atmospheric phenomena. Economical and easy-maintenance anticorrosion system should be developed such as combination of ACM (atmospheric corrosion measuring) sensor and washer. The causes of corrosion, which spoils function, are mainly classified into macro-galvanic-cell corrosion, and unintended environmental condition such as condensation, oxidizing agent (e.g. chlorine gas), and pH (e.g. carbon dioxide and hydrogen sulfide). The building is composed of the materials of wide-use so that defect of materials (e.g. welded area of stainless steel and carbon membrane of soft copper tube) is less likely to be the cause of corrosion. Therefore, effective anticorrosion can be planned during design phase of the building. Unfortunately, few architects and engineers have proper understandings about anticorrosion method. It is not tolerated that the materials which can survive several decades, are abandoned within few years. Total amount of building materials is so enormous that small loss ends up to the incredibly huge loss. Global and nation-wide actions should be considered.
Corrosion behaviors and its countermeasures of copper used for building materials such as roofs and water supply systems in detached houses, apartments and buildings have been reviewed. The corrosion phenomena of pitting corrosion, erosion corrosion and cuprosolvency troubles are discussed based on both empirical data and experimental data. Especially, pitting corrosion of copper tubes are classified into five kinds of types in terms of the nature of the corrosion products, the structure of the corrosion pits and possible causes: Type I′, Type I″-A, Type I″-B, Type II and Moundless. The countermeasures for each corrosion problems also are discussed.
We have past the 50-year landmark of aluminum anodizing industrialization for architecture in Japan. The evolution, resent developments, and current-status of aluminum surface finishing technology, and industry will be reviewed along the various application segments.
Much attention has been devoted to titanium as a new architectural material. This is because that titanium has its advantages of combining light weight with high strength and excellent corrosion resistance especially in chloride environments. This paper reviews the various characteristics such as corrosion and mechanical properties of titanium as an architectural material. Surface treatment technologies such as vacuum annealing process, continuous annealing pickling process, anodic oxidation process for coloring, etc, and their application to architectural field are also described. Furthermore, the market trends and use experiences of titanium in the building and construction field are surveyed. More than 20 years have passed since titanium was first used and about 150 to 200 tons per year are recently used as an architectural material in Japan.
The polymer-polymer complexes [(PMAAN/PAAmM)c], composed of polymethacrylic acid [PMAAN, N=1(Mn=1.0×104), 2(Mn=5.0×103) and 3(Mn=2.5×103)] and polyacrylamide [PAAmM, M=1 (Mn=5.0×103) and 2(Mn=2.5×103)] were investigated as inhibitors for corrosion of mild steel in cooling water systems. The inhibition abilities of (PMAAN/PAAmM)c against corrosion and scale deposition were evaluated by corrosion tests and physicochemical methods. In a solution with low concentration of ionic species (LC solution), the corrosion inhibition abilities of (PMAAN/PAAmM)c improved at an addition of the polymer higher than 50ppm. This effect is due to the control of adsorption of the polymers on steel surfaces based on the formation of polymer-polymer complexes. In a solution with high concentration of ionic species (HC solution), the corrosion inhibition abilities of (PMAAN/PAAmM)c were also favorable at an addition of the polymer higher than 20ppm. This effect is attributed to control of the adsorption of the polymers on steel surfaces and the scale dispersion based on the formation of polymer-polymer complexes.
The effect of galvanized corrosion steel sheets and zinc-rich primer coated steel sheets on the perforation corrosion of actual automobiles and the relevant corrosion mechanism was studied. Perforation occurred in 6-7 years for zinc-rich primer coated steel panels inside of door hems and after more than 14 years for galvanized steel sheets with 120g/m2 zinc coating mass in the lapped side-sill. Perforation corrosion of galvanized steel panels can be divided into 4 corrosion processes on the basis of measured perforation depth and analysis of iron rust for North American automobile bodies. The period in which zinc corrosion controls the corrosion of the steel substrate played a very important role in determining the period until perforation occurs in road salting regions.
Corrosion mechanism of organic-composite-coated steel sheets (OCS) in iron rust containing environments was investigated. Cathodic current density of OCS increased and its corrosion potential changed to noble when iron rust was added to NaCl solution. Magnetite changed the corrosion potential of OCS to noble and accelerated its corrosion. It has been speculated that the degradation of corrosion resistance in iron rust containing environments is caused by the high cathodic current density on the surface of magnetite that has the higher electro-conductivity.