What are the classification and characteristics of copper?

1. Red copper: refers to pure copper, the main varieties are oxygen-free copper, red copper, phosphorus deoxidized copper, silver copper;

2. Brass: refers to an alloy based on copper and zinc, which can be subdivided into simple brass and complex brass. In complex brass, the third component is named nickel brass, silicon brass, etc.;

3. Bronze: refers to copper-based alloys other than copper-nickel and copper-zinc alloys. The main varieties are tin bronze, aluminum bronze, and special bronze (also known as high copper alloy);

4. Cupronickel: refers to copper-nickel alloy.

Copper can be used to make a variety of alloys. The important copper alloys are as follows:
1. Brass: Brass is an alloy of copper and zinc, named after its yellow color. Brass has good mechanical properties and wear resistance, and can be used to manufacture precision instruments, ship parts, and gun shells. Brass sounds good when knocked, so gongs, cymbals, bells, and horns are all made of brass.

2. Nautical brass: an alloy of copper, zinc and tin, resistant to seawater erosion, and can be used to make ship parts and balancers.

3. Bronze: The alloy of copper and tin is called bronze, which is named for its blue color. In ancient times, it was a common alloy (such as the Bronze Age in China). Bronze generally has good corrosion resistance, wear resistance, castability and excellent mechanical properties.

4. Phosphor bronze: an alloy of copper, tin and phosphorus, hard, and can be used to make springs.

5. Cupronickel: Cupronickel is an alloy of copper and nickel. Its color is the same as that of silver. It is shiny and not easy to rust. Commonly used in the manufacture of coins, electrical appliances, meters and decorations.

6. Eighteen carat gold (18K gold or rose gold): an alloy of 6/24 copper and 18/24 gold. Red and yellow, with high hardness, it can be used to make jewelry and decorations.