The corrosion resistance of cast iron is markedly enhanced by incorporating 12–15% of___________________?
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Answer: C. Silicon
Explanation
The correct answer is silicon because incorporating 12 to 15 percent silicon forms protective silica films on the iron. This high silicon concentration creates a continuous surface barrier that resists severe acid attack and chemical oxidation. It transforms standard cast iron into a specialized high-silicon corrosion-resistant alloy suitable for aggressive chemical service. High-silicon cast irons are specialized ferrous alloys designed specifically for handling highly corrosive industrial chemicals. Silicon forms a tenacious silicon dioxide film on the metal surface that protects the iron matrix from acid dissolution. However, increasing the silicon content also makes the alloy extremely hard and brittle, requiring careful mechanical handling.
Option A is incorrect because tungsten is used to improve high-temperature tool hardness rather than acid corrosion resistance. Option B is incorrect because vanadium is a grain refiner used in structural steels rather than a corrosion inhibitor for cast iron. Option D is incorrect because only silicon among the listed elements provides the necessary high-percentage corrosion resistance.
- Subject
- Engineering
- Category
- Chemical Engineering
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- —
- Difficulty
- medium
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