Identify the incorrect statement concerning metal electroplating or coating?
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Answer: D. Calorising is the process of coating steel with chromium
Explanation
Calorising is a high-temperature diffusion coating process used to alloy steel surfaces with aluminum. Coating steel surfaces with chromium is known as chromizing rather than calorising metal treatment. The incorrect statement misidentifies the specific alloying element applied during the calorising process. Phosphate conversion coatings create microcrystalline layers that provide excellent corrosion resistance and paint adhesion. Chromate coatings offer superior barrier corrosion resistance compared to standard phosphate conversion layers. Electroplating baths use the substrate metal as the negative cathode where dissolved metal ions deposit.
Automotive manufacturing relies on phosphate pretreatments before painting to prevent sub-film corrosion. Surface engineering techniques protect structural steels from oxidation and wear in aggressive environments. Selecting appropriate surface treatments extends the operational service life of engineered metal components. Phosphate coatings serve as exceptional base layers for paints, primers, and organic enamels. Phosphate conversion layers provide lower corrosion resistance than specialized chromate protective coatings. Electroplating setups require the component being coated to serve as the cathode in the electrolytic cell.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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