write the ways to prevent corossion
Answers
Answer:
Corrosion is a deterioration of a material caused by environmental interactions. It is a natural phenomenon, requiring three conditions: moisture, a metallic surface, and an oxidizing agent known as an electron acceptor. The process of corrosion converts the reactive metal surface into a more stable form, namely its oxide, hydroxide, or sulfide. A common form of corrosion is rust.
You can prevent corrosion by selecting the right:
Metal Type
Protective Coating
Environmental Measures
Sacrificial Coatings
Corrosion Inhibitors
Design Modification
Answer: 1. Barrier Coatings
One of the easiest and cheapest ways to prevent corrosion is to use barrier coatings like paint, plastic, or powder. Powders, including epoxy, nylon, and urethane, are heated to the metal surface to create a thin film. Plastic and waxes are often sprayed onto metal surfaces. Paint acts as a coating to protect the metal surface from the electrochemical charge that comes from corrosive compounds. Today’s paint systems are actually a combination of different paint layers that serve different functions. The primer coat acts as an inhibitor, the intermediate coat adds to the paint’s overall thickness, and the finish coat provides resistance to the environmental factors.
The biggest drawback with coatings is that they often need to be stripped and reapplied. Coatings that aren’t applied properly can quickly fail and lead to increased levels of corrosion. Coatings may also contain volatile organic compounds, which can make them vulnerable to corrosion.
2. Hot-Dip Galvanization
This corrosion prevention method involves dipping steel into molten zinc. The iron in the steel reacts with the zinc to create a tightly-bonded alloy coating which serves as protection. The process has been around for more than 250 years and has been used for corrosion protection of things like artistic sculptures and playground equipment. Compared to other corrosion prevention methods, galvanization is known for lower initial costs, sustainability, and versatility.
Unfortunately, galvanization can’t be done on-site, meaning companies have to pull equipment out of work to be treated. Some equipment may simply be too large for the process, forcing companies to abandon the idea altogether. In addition, if the process isn’t done properly, the zinc can chip or peel. And high exposure to environmental elements can speed up the process of zinc wear, leading to increased maintenance check-ups. Lastly, the zinc fumes that release from the galvanizing process are toxic.
3. Alloyed Steel (Stainless)
Alloyed steel is one of the most effective corrosion prevention methods around, combining the properties of various metals to provide added strength and resistance to the resulting product. Corrosion-resistant nickel, for example, combined with oxidation-resistant chromium results in an alloy that can be used in oxidized and reduced chemical environments. Different alloys provide resistance to different conditions, giving companies greater flexibility.
Despite its effectiveness, alloyed steel is very expensive. Companies with limited financial resources will likely have to turn to other methods. Monitoring surface conditions are critical, as cracks or scratches can result in an increase of corrosion. Companies also need to make sure the agents used in maintenance don’t include corrosion properties.
4. Cathodic Protection
Cathodic protection protects against galvanic corrosion, which occurs when two different metals are put together and exposed to a corrosive electrolyte. To prevent this, the active sites on the metal surface need to be converted to passive sites by providing electrons from another source, typically with galvanic anodes attached on or near the surface. Metals used for anodes include aluminum, magnesium, or zinc.
While cathodic protection is highly effective, anodes need to be checked often which can drive up costs of maintenance. They also increase the weight on the attached structure and aren’t always effective in high-resistivity environments. Finally, anodes lead to increased water flow on ships and other underwater equipment.
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