What is the difference between red copper, brass, bronze and cupronickel? What are the characteristics of each?

White copper, brass, red copper (also known as "red copper"), and bronze (blue-gray or gray-yellow) are distinguished by color, among which white copper and brass are very easy to distinguish; red copper (pure copper, impurities <1%) , Bronze (other alloy composition is about 5%) is slightly difficult to distinguish. When it is not oxidized, the color of red copper is brighter than that of bronze, and the bronze is slightly cyan or yellow. After oxidation, the copper becomes black, and the bronze is turquoise (harmful oxidation of water) or chocolate. Bronze originally refers to copper-tin alloys, and later copper alloys other than brass and cupronickel are called bronzes, and are often given the name of the first main added element before the name of bronze. Tin bronze has good casting performance, anti-friction performance and good mechanical performance, and is suitable for manufacturing bearings, worm gears, gears, etc. Lead bronze is a widely used bearing material for modern engines and grinders. Aluminum bronze has high strength, good wear resistance and corrosion resistance, and is used for casting high-load gears, bushings, marine propellers, etc. Beryllium bronze and phosphor bronze have high elastic limit and good electrical conductivity, and are suitable for the manufacture of precision springs and electrical contact elements. Beryllium bronze is also used to make non-sparking tools used in coal mines and oil depots.

Cupronickel is a copper alloy with nickel as the main additive element. The copper-nickel binary alloy is called ordinary cupronickel; the cupronickel alloy with manganese, iron, zinc, aluminum and other elements is called complex cupronickel. Industrial cupronickel is divided into two categories: structural cupronickel and electrical cupronickel. The characteristics of structural cupronickel are good mechanical properties and corrosion resistance, and beautiful color. This cupronickel is widely used in the manufacture of precision machinery, chemical machinery and ship components. Electrical cupronickel generally has good thermoelectric properties. Manganin, constantan and test copper are manganese cupronickel with different manganese content, which are used in the manufacture of precision electrical instruments, varistors, precision resistors, strain gauges, thermocouples, etc. Compared with other copper alloys, cupronickel has excellent mechanical and physical properties, good ductility, high hardness, beautiful color, corrosion resistance, and deep drawing performance; the disadvantage is that the main added element - nickel is a scarce strategic material, and the price is relatively expensive . First, let's understand pure copper. Red copper is a type of copper with the highest copper content, and the copper content reaches 99.5%-99.95%, so it can also be called pure copper. Pure copper is elemental copper with high purity. Because pure copper is oxidized to form a purple oxide film on the surface, it is also called red copper or red copper, which has a rose red color. Copper is generally refined by electrolysis, and the purity of copper obtained by refining can reach 99.99%. At the same time, copper has good plasticity and softness, which is convenient for shaping and installation. Copper is malleable, and pure copper the size of a drop of water can be stretched into filaments up to two kilometers long, or rolled into almost transparent foils larger than a bed. In terms of performance, red copper has good plasticity and electrical and thermal conductivity, so it is often used in cables, wires, and heat-dissipating components.

Brass is a kind of copper containing other alloy components. Its conductivity and plasticity are slightly worse than that of red copper, but its strength and hardness are higher. From the appearance, the color of the brass surface is yellow, so it is called brass.

Brass is an alloy of copper and zinc. The simplest brass is a copper-zinc binary alloy, called simple brass or ordinary brass, and brass with different mechanical properties can be obtained by changing the zinc content in brass. The higher the zinc content in brass, the higher the strength and the lower the plasticity. The zinc content of brass used in the industry does not exceed 45%. No matter how high the zinc content is, it will cause brittleness and deteriorate the alloy properties.

Adding 1% tin to brass can significantly improve the resistance of brass to seawater and marine atmospheric corrosion, so it is called "navy brass", and tin can improve the machinability of brass. Lead brass is what we usually call easy-cutting national standard copper. The main purpose of adding lead is to improve machinability and wear resistance, and lead has little effect on the strength of brass. Engraved copper is also a type of lead brass. Most brasses have good color, workability, ductility, and are easy to electroplate or paint.

In industry and civil use, different materials are selected according to different use characteristics. Such as wire, the requirement is softer, copper is better. If it is used as a connecting piece, the place where the screw is attached is mostly made of brass.

Bronze is the earliest alloy in the history of metal smelting. The addition of tin or lead to pure copper (red copper) has special importance and historical significance. Compared with pure copper (red copper), bronze has high strength and low melting point (25%). The tin smelting bronze, the melting point will be reduced to 800 ° C. The melting point of pure copper (red copper) is 1083 ° C). Bronze has good castability, wear resistance and chemical stability.