What is metal spraying?

• A. The surface application of molten metal on any ferrous solid base material.
• B. The deposition of plastic coatings on copper.
• C. The conversion coating of aluminum.
• D. The chemical cleaning of steel.

Answer: (A)

Metal spraying is the surface application of molten or semi-molten metal onto a base material to form a protective or functional coating. The sprayed metal is heated and propelled toward the surface, where it impacts, spreads, and rapidly cools to form a coherent layer that adheres mainly by mechanical interlocking (and, in some processes, metallurgical bonding). This technique is commonly used to protect ferrous substrates from corrosion and wear, and to restore dimensions or add surface properties. The other described processes—depositing plastics, applying conversion coatings, or cleaning—are different types of surface treatments and not what metal spraying entails.