Types and characteristics of Cu

Cu is a metal widely used in industry and life, with excellent electrical conductivity, thermal conductivity, corrosion resistance and processing performance. The following are the main types and characteristics of Cu:

Red copper refers to pure copper, the main varieties are oxygen-free copper, red copper, phosphorus-deoxidized copper, and silver copper; pure copper is a purple-red metal, commonly known as "red copper", "red copper" or "red copper". Pure copper is ductile. A drop of pure copper, the size of a drop of water, can be drawn into a filament up to two kilometers long, or rolled into an almost transparent foil larger than a bed. The most valuable property of pure copper is its excellent 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 that of 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 dull, with a copper content of more than 99.95%. A very small amount of impurities, especially phosphorus, arsenic, aluminum, etc., will greatly reduce the conductivity of copper. The oxygen content in copper (a small amount of oxygen is easily mixed in during copper smelting) has a great influence on the conductivity. Copper used in the electrical industry generally must be oxygen-free copper. In addition, impurities such as lead, antimony, and bismuth will prevent the crystals of copper from combining together, causing hot brittleness and affecting the processing of pure copper. This kind of pure copper with high purity is generally refined by electrolysis: impure copper (i.e. crude copper) is used as the anode, pure copper is used as the cathode, and copper sulfate solution is used as the electrolyte. When the current passes through, the impure copper on the anode gradually melts, and the pure copper gradually precipitates on the cathode. The copper refined in this way can reach a purity of 99.99%. Red copper is a relatively pure type of copper, which can generally be considered as pure copper. It has good conductivity and plasticity, but poor strength and hardness.

Brass is a type of copper containing other alloy components. It is cheaper than red copper, and its conductivity and plasticity are slightly worse than red copper, but its strength and hardness are higher. It can also be subdivided into simple brass and complex brass. Complex brass is named nickel brass, silicon brass, etc. with the third component; Brass is an alloy of copper and zinc. The simplest brass is a copper-zinc binary alloy, called simple brass or ordinary brass. Changing the zinc content in brass can produce brass with different mechanical properties. The higher the zinc content in brass, the higher its strength and slightly lower plasticity. The zinc content of brass used in industry does not exceed 45%. Higher zinc content will produce brittleness and deteriorate the alloy performance. Adding 1% tin to brass can significantly improve the brass's ability to resist seawater and marine atmospheric corrosion, so it is called "naval brass". Tin can improve the cutting performance of brass. Lead brass is what we usually call easy-to-cut national standard copper. The main purpose of adding lead is to improve cutting processability and wear resistance. Lead has little effect on the strength of brass. Engraving copper is also a kind of lead brass. Most brasses have good color, processability, ductility, and are easy to electroplate or paint. In industry and civil use, different materials are selected according to different usage characteristics. For example, for making wires, it is required to be softer, so red copper is better. For example, for bearings and connectors, brass is often used for screws.

Bronze originally refers to copper-tin alloy. Later, copper alloys other than brass and nickel silver are called bronze, and the name of the first main added element is often added before the name of bronze. Tin bronze has good casting performance, anti-friction performance and mechanical properties, 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 to cast high-load gears, bushings, marine propellers, etc. Beryllium bronze and phosphor bronze have high elastic limits and good conductivity, and are suitable for manufacturing precision springs and electrical contact elements. Beryllium bronze is also used to manufacture spark-free tools used in coal mines, oil depots, etc.

Nickel silver is a copper alloy with nickel as the main added element. Copper-nickel binary alloy is called ordinary nickel silver; nickel silver alloys with manganese, iron, zinc, aluminum and other elements are called complex nickel silver. Industrial nickel silver is divided into two categories: structural nickel silver and electrical nickel silver. Structural nickel silver is characterized by good mechanical properties and corrosion resistance, and beautiful color. This type of white copper 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 copper are manganese white coppers with different manganese contents. They are materials used to manufacture precision electrical instruments, varistors, precision resistors, strain gauges, thermocouples, etc.