Corrosion and Materials Degradation

This paper presents comprehensive studies of pitting corrosion, which precedes the appearance of fistulas in galvanized steel pipelines of hot and cold water supply systems. Corroded galvanized pipes taken out from water supply systems within their operation and scale samples were the subject of this research. The current work continues the research on one of the four structural elements of tubercles—the dense layer. The corrosion of the zinc coating and the steel base of pipes inside the tubercles led to a gradual increase in the concentration of a solution containing components of the corroding metal (zinc and iron cations) and anions in water (mainly chlorides and sulfates). To explain the corrosion under the tubercles, their dense layer was compared with an anion exchange membrane with selective properties, which provided the primary concentration of the salt solution in the structure of the tubercles with a significant increase in the concentration of aggressive anions compared to the source water. The formation of fistulas in the cavity leads to a secondary concentration of solution inside the tubercle, mainly consisting of iron chloride. At the same time, due to the hydrolysis of the formed iron salts and a decrease in pH, the corrosion rate increases and becomes independent of external conditions. This article summarizes ten years of experience in examining corrosion of steel pipes from external and internal water supply systems.

This paper reviews results published by the International Co-operative Programme on Effects on Materials including Historic and Cultural Monuments (ICP Materials) with emphasis on those obtained after the turn of the century. Data from ICP Materials come from two main sources. The first is through exposures of materials and collection of environmental data in a network of atmospheric exposure test sites mainly distributed across Europe. Corrosion of carbon steel has continued to decrease during the period 2000–2020 but corrosion of zinc only up until 2014, and the trend in zinc corrosion is only visible when examining four-year data. Surface recession of limestone as well as soiling of modern glass show no decreasing trend during 2000–2020. The second is through case studies performed at heritage sites across Europe. Risk analysis of corrosion and soiling for twenty-six sites indicate that currently soiling is a more significant maintenance trigger than corrosion. Costs for maintaining heritage sites are substantial and costs attributable to air pollution is estimated from 40% to as much as 80% of the total cost. Future directions of the program are work on effects of particulate matter, improving the scientific basis for the work, and making the monitoring data publicly available.

Atmospheric corrosion in sand dust environments is driven by deposits that bear chloride, which sustain thin electrolyte layers on metal surfaces. We established a laboratory protocol to replicate this by extracting, formulating, and depositing a preliminary layer of mixed salts from natural dust onto samples, with humidity precisely set using the salt’s deliquescence behavior. Degradation was tracked with SEM/EDS, 3D profilometry, XRD, and electrochemical analysis. Bare steel showed progressive yet decelerating attack as rust evolved from discrete islands to a lamellar network; while this densification limited transport, its internal cracks and interfacial gaps trapped chlorides, sustaining activity beneath the rust. In contrast, QPQ-treated steel remained largely protected, with damage localized at coating defects as raised rust nodules, while intact regions maintained low electrochemical activity. By coupling salt chemistries derived from the field with humidity control guided by deliquescence and diagnostics across multiple scales, this study provides a reproducible laboratory pathway to predict atmospheric corrosion.