Cupronickel

Cupronickel is an alloy made primarily of copper and nickel, sometimes with small additions of other elements. Its resistance to corrosion, especially in seawater, suits it to coins, marine equipment, and heat exchangers.

Copper: Copper is a ductile, conductive metal with atomic number 29. It forms the majority of most cupronickel alloys and contributes conductivity and formability.
Passivation: Passivation is the formation of a thin surface layer that slows a material’s corrosion. A protective surface film helps cupronickel withstand prolonged exposure to seawater.
United States nickel: The United States five-cent coin, commonly called the nickel, made of a copper–nickel alloy. The coin’s cupronickel composition is a familiar use of the alloy outside marine engineering.
Brass: Brass is a copper alloy whose principal additional element is zinc. Brass is another copper alloy, but its zinc-based composition gives it different marine performance.
Nickel: Nickel is a corrosion-resistant transition metal with atomic number 28. Adding nickel strengthens copper and improves its resistance to seawater corrosion.
Galvanic corrosion: Galvanic corrosion is accelerated metal deterioration caused by electrical contact with a dissimilar metal in an electrolyte. Marine installations can undermine cupronickel when it is electrically coupled to less noble metals.
Copper-nickel coinage: Coinage made from alloys containing copper and nickel, used by many countries for circulating coins. Cupronickel’s durability and distinctive appearance suit coins handled and circulated repeatedly.
Bronze: Bronze is a copper alloy, traditionally made with tin as its principal addition. Bronze contrasts with cupronickel in alloying element and typical mechanical and corrosion properties.
Copper–nickel phase diagram: A phase diagram showing the phases formed by copper–nickel alloys at different compositions and temperatures. It explains why copper and nickel form a continuous family of solid solutions.
Erosion corrosion: Erosion corrosion is material loss caused by the combined action of fluid flow and corrosion. Fast seawater flow can damage cupronickel surfaces despite their general corrosion resistance.

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List of copper alloysBroader topic: It is a copper-alloy family defined by nickel rather than zinc or tin.