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Corrosion Resistance & Coatings Flashcards

7 cards from real CFS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. Mechanical galvanizing differs from hot-dip galvanizing primarily because it:

    Answer: Uses tumbling with zinc powder at room temperature instead of a molten bath

    Mechanical galvanizing cold-welds zinc powder onto fasteners via tumbling with glass beads and does not involve a molten zinc bath, avoiding hydrogen embrittlement.

  2. What does ASTM F1941 govern regarding fastener coatings?

    Answer: Electrodeposited coatings on threaded fasteners

    ASTM F1941 specifies requirements for electrodeposited coatings on threaded fasteners including dimensional and performance requirements.

  3. Which environmental condition accelerates corrosion most significantly on bare carbon steel fasteners?

    Answer: High humidity combined with chloride ions

    The combination of high humidity and chloride ions is particularly aggressive, as chlorides break down passive films and water acts as the electrolyte for corrosion reactions.

  4. The minimum zinc coating weight for hot-dip galvanized structural bolts per ASTM A563 nut standards is closest to:

    Answer: 1.7 oz/ft²

    ASTM A153 requires approximately 1.7 oz/ft² (Class C) for threaded fasteners in hot-dip galvanizing applications.

  5. Grade 5 fasteners electroplated with cadmium were historically popular in aerospace primarily because cadmium:

    Answer: Provides excellent corrosion protection and is compatible with aluminum

    Cadmium plating provides excellent corrosion resistance, low contact resistance, and is galvanically compatible with aluminum airframes, making it historically popular in aerospace.

  6. Which term describes the ability of a coating to heal small scratches or damage through migration of protective ions?

    Answer: Self-healing or galvanic sacrificing

    Zinc coatings self-heal minor damage through galvanic sacrificing, where zinc ions from the intact coating migrate to protect the exposed base metal.

  7. Thread fit after hot-dip galvanizing typically requires nuts to be:

    Answer: Tapped oversize to accommodate the thicker zinc coating

    Hot-dip galvanized bolts have significantly thicker coatings than electroplated fasteners, requiring nuts to be tapped oversize per ASTM A563 to achieve proper thread engagement.