Corrosion in industries Automotive.pptx

Corrosion in industries
Automotive

1. Corrosion in the Automotive Industry

2. AUTOMOTIVE Corrosion in industries Factors Mechanism Prevention and control 1️⃣Temperature 2️⃣ Humidity and chemicals 1️⃣Galvanic Corrosion 2️⃣Chemical Corrosion 1️⃣Material Advances 2️⃣Coating Applications

3. Factors Temperature Rise in temperature increases the rate of corrosion due to increase in the rate of diffusion of ions. Humidity The rate of corrosion will be more when the relative humidity of the environment is high. The moisture acts as a solvent for oxygen, CO2, SO2 etc in the air to produce the electrolyte which is required for setting up of an electrochemical cell.

4. Chemicals -Acid Rain: Acid rain contains weak acids, such as sulfuric acid and nitric acid, which can react with the car body and cause corrosion.
-Road Salt: Road salt is used on roads during winter to prevent freezing, but it can react with the car body and cause corrosion.
-Car Wash Chemicals: Some car wash chemicals contain harsh chemicals that can react with the car body and cause corrosion.
-Gasoline and Fuel: Spills or leaks of gasoline or fuel from the fuel tank or fuel lines can react with the car body and cause corrosion.
-Glass Cleaners: Some glass cleaners contain harsh chemicals that can react with the car body and cause corrosion .

5. Mechanism 1️⃣Galvanic corrosion 1. Car body (steel) and copper mounting screws:
-Visual: You might see rust forming around the screw holes on the car body, with the area closest to the screw showing the most significant deterioration.
-Explanation: Steel (anode) is less noble than copper (cathode), so the steel corrodes faster where it touches the copper screw in the presence of moisture (electrolyte ). 2. Aluminum car paint and exposed steel:
-Visual: You might see bubbles or cracks in the paint near exposed steel areas, with the steel underneath showing rust.
-Explanation: Aluminum (cathode) is more noble than steel (anode), so the exposed steel corrodes faster where it touches the aluminum paint in the presence of moisture .

6. Prevention and Control 1️⃣Material Advances -Protective Coatings: Applying waxes, sealants, or specialized anti-corrosion coatings provides a physical barrier between the metal and corrosive elements in the environment.
-Cathodic Protection: In some cases, applying electrical currents can suppress corrosion on specific structures like car frames. However, this method is typically used for large-scale applications.
-Design Considerations: Designing cars with improved drainage and minimizing areas where water can accumulate helps prevent moisture-induced corrosion.
-Galvanic Compatibility: Selecting materials with similar corrosion potential when they come in contact (e.g., using aluminum screws with aluminum body panels) minimizes the risk of galvanic corrosion, which occurs when dissimilar metals are in close contact .

7. -Powder Coatings: These dry coatings are electrostatically applied and then cured with heat. They offer excellent corrosion resistance, durability, and chip resistance. Powder coatings are often used for car frames and undercarriage components.
-Zinc Coatings (Galvanization): A common and effective method, galvanization involves coating steel with zinc, which acts as a sacrificial anode. When exposed, the zinc corrodes first, protecting the underlying steel. This is why you see a white, flaky substance on older cars – it’s the zinc sacrificing itself.
-Conversion Coatings: These chemical treatments convert the metal surface into a corrosion-resistant phosphate layer. Conversion coatings often serve as a pre-treatment for other coatings, enhancing their adhesion and effectiveness. Coating Applications