Pure copper is a purple-red metal, commonly known as "red copper", "red copper" or "red copper". Pure copper is malleable. Pure copper, the size of a drop of water, can be drawn into filaments up to two kilometers long, or rolled into almost transparent foil larger than the bed. The most valuable property of pure copper is its very good electrical conductivity, second only to silver among all metals, so it has become the "protagonist" of the electrical industry.
The use of pure copper is much more extensive than pure iron. Every year, 50% of copper is electrolytically purified into pure copper for use in the electrical industry. The pure copper mentioned here must be very blunt, with a copper content of over 99.95%. Very small amounts of impurities, especially phosphorus, arsenic, aluminum, etc., will greatly reduce the conductivity of copper. Oxygen in copper (a small amount of oxygen is easily mixed during copper smelting) has a great influence on conductivity, and copper used in the electrical industry must generally be oxygen-free copper. In addition, impurities such as lead, antimony, and bismuth will make the copper crystals unable to bond together, causing hot embrittlement, and also affect the processing of pure copper. This kind of pure copper with high purity is generally refined by electrolysis: impure copper (that is, blister copper) is used as anode, pure copper is used as cathode, and copper sulfate solution is used as electrolyte. When the current is passed, the impure copper on the anode gradually melts, and the pure copper gradually precipitates on the cathode. The copper refined in this way has a purity of 99.99%.
Red copper is a relatively pure type of copper, which can generally be approximated as pure copper. It has good electrical conductivity and plasticity, but its strength and hardness are relatively poor.
Properties and uses of brass:
Brass is a kind of copper that contains other alloy components. The price is cheaper than copper. Its conductivity and plasticity are a little bit worse than copper, but its strength and hardness are higher.
Brass is an alloy of copper and zinc. The simplest type of brass is a copper-zinc binary alloy, called simple brass or ordinary brass. Brass with different mechanical properties can be obtained by changing the zinc content in the brass. The higher the zinc content in brass, the higher its strength and lower plasticity. The zinc content of brass used in industry does not exceed 45%. No matter how high the zinc content is, it will produce brittleness and deteriorate the properties of the alloy. Adding 1% tin to brass can significantly improve the resistance of brass to corrosion by sea water and ocean atmosphere, so it is called "navy brass". Tin can improve the cutting performance of brass. Lead brass is what we usually call easy-cutting national standard copper. The main purpose of adding lead is to improve the machinability and wear resistance. Lead has little effect on the strength of brass. Engraved copper is also a type of lead brass. Most brass has good color, processability, ductility, and is easy to be electroplated or painted.
In industrial and civil applications, different materials are selected according to different usage characteristics. For wire, it requires softness, and copper is better. For connecting parts, brass is mostly used for screwing.
Properties and uses of bronze:
Originally refers to copper-tin alloy, later copper alloys other than brass and cupronickel are called bronze, and the name of the bronze is often named as the first main additive element. 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 bearing material widely used in modern engines and grinders. Aluminum bronze has high strength, good wear resistance and corrosion resistance, and is used for casting high-load gears, bushings, and marine propellers. Beryllium bronze and phosphor bronze have high elastic limit and good conductivity, and are suitable for manufacturing precision springs and electrical contact components. Beryllium bronze is also used to make non-sparking tools used in coal mines and oil depots.
Properties and uses of copper-nickel alloy:
A copper alloy with nickel as the main additive element. The copper-nickel binary alloy is called ordinary cupronickel; the cupronickel alloy with elements such as manganese, iron, zinc, and aluminum is called complex cupronickel. Industrial copper-nickel alloy is divided into two categories: structural copper-nickel alloy and electrical copper-nickel alloy. Structural white copper is characterized by good mechanical properties and corrosion resistance, and beautiful color. This copper-nickel alloy is widely used in the manufacture of precision machinery, chemical machinery and ship components. Electrical white copper generally has good thermoelectric properties. Manganese copper, constantan and test copper are manganese cupronickel with different manganese content, which are used to manufacture precision electrical instruments, varistors, precision resistors, strain gauges, thermocouples, etc.
How to distinguish between copper, brass, bronze and cupronickel:
Cupronickel, brass, copper (also known as "red copper"), bronze (green gray or grayish yellow) are distinguished by color. Among them, cupronickel and brass are easily distinguished; red copper is pure copper (impurity <1%) ), bronze (about 5% of other alloy components) is slightly difficult to distinguish. When it is not oxidized, the red copper is brighter than bronze, and the bronze is slightly cyan or yellowish darker; after oxidation, the red copper becomes black, and the bronze is cyan (harmful oxidation due to water) or chocolate.
