Nickel processing

Copper-nickel

The addition of copper to nickel provides a series of useful alloys. Monel metal, 67 percent nickel and the balance essentially copper, is stronger than nickel and has broad corrosion-resisting applications. Extremely resistant to rapidly flowing seawater, it has many marine uses. The addition of a small percentage of aluminum and titanium renders it precipitation-hardenable; this high-strength version is widely used for propeller shafts. Increasing copper to 55 percent produces the electrical resistance alloy known as constantan, which is used as a thermocouple in conjunction with pure copper.

The 30 percent and 10 percent nickel-copper alloys, usually containing 0.5 percent and 1.5 percent iron, are widely used in the form of tubes for heat interchangers and condensers. Their resistance to seawater corrosion makes them important in desalination plants. Copper-based alloys containing a small percentage of nickel become precipitation-hardenable if 5–8 percent tin or a smaller amount of silicon or phosphorus is added. These have special uses.

The ancient Chinese alloy pai-t’ung, now known as nickel-silver, contains 10–30 percent nickel with the balance copper plus zinc. This alloy continues as a favoured base for silver-plated ware. It also is used as a spring material for relays and ... (200 of 3,364 words)