The main forms of corrosion affecting building metals are diverse and can significantly impact the structural integrity and longevity of materials. Understanding these types is essential for selecting appropriate materials and protective measures.
1. Uniform Corrosion: This occurs when the entire surface of a metal corrodes evenly, leading to a consistent thinning of the material. The annual average thickness loss is commonly used to measure the corrosion rate. Steel, for example, typically experiences uniform corrosion in atmospheric conditions, making it a key factor in assessing long-term durability.
2. Pitting Corrosion: This type of corrosion appears as small, localized holes or pits on the metal surface. It often develops due to the specific properties of the metal and the environment it's exposed to. Chloride-containing environments, such as coastal areas or those with de-icing salts, are particularly prone to pitting. The depth of the pits is an important indicator, especially in critical applications like pipeline systems where even minor damage can lead to major failures.
3. Galvanic Corrosion: This happens when two different metals are in contact in the presence of an electrolyte. The difference in their electrochemical potentials causes one metal to corrode more rapidly than the other. Proper material selection and isolation techniques are crucial to prevent this form of corrosion in construction projects.
4. Crevice Corrosion: This occurs in tight spaces or gaps where the medium (like water or air) cannot circulate freely. Differences in oxygen concentration and chemical composition within these areas can accelerate corrosion. Common in joints, seams, and under gaskets, this type of corrosion is often difficult to detect until significant damage has occurred.
5. Stress Corrosion Cracking: This involves the formation of cracks on the metal surface under the combined influence of a corrosive environment and tensile stress. It is particularly dangerous because it can lead to sudden failure without much visible warning. High-strength steel bars and wires in concrete structures are vulnerable to this type of damage, which can compromise the safety and stability of buildings over time.
Shandong Zeen Decoration Material Co., Ltd. , https://www.zeendecor.com