Here's everything you need to know about copper
Copper is a transition element, with the chemical symbol Cu, and the English name copper. Pure copper is a soft metal. When the surface is just cut, it is red-orange with a metallic luster, and the single substance is purple-red. It has good ductility, high thermal conductivity and electrical conductivity, so it is the most commonly used material in cables and electrical and electronic components. It can also be used as a building material and can form many kinds of alloys. Copper alloys have excellent mechanical properties and very low resistivity, among which bronze and brass are the most important. In addition, copper is also a durable metal that can be recycled many times without damaging its mechanical properties.
Material properties and characteristics
Copper is a metal that exists in the earth's crust and oceans. The content of copper in the earth's crust is about 0.01%, and in some copper deposits, the content of copper can reach 3% to 5%. Most of the copper in nature exists as compounds, namely copper ores.
Copper has good physical and chemical properties such as electrical conductivity, thermal conductivity, non-magnetic, corrosion resistance and ductility. The electrical conductivity and thermal conductivity are second only to silver. Pure copper can be drawn into very fine copper wires and made into very thin copper foil. The fresh cross section of pure copper is rose red, but after the copper oxide film is formed on the surface, the appearance is purple-red, so it is often called red copper.
1. Electrical conductivity and thermal conductivity: Copper's electrical conductivity and thermal conductivity are second only to silver. And the price is much lower than gold and silver. Pure copper can be drawn into very fine copper wire and made into very thin copper foil.
2. Corrosion resistance: Generally speaking, copper's corrosion resistance is lower than that of gold, platinum, silver and titanium, while gold, platinum and silver are precious metals and their actual application scale is very small; compared with metals such as iron, zinc and magnesium, copper has strong corrosion resistance. Compared with aluminum, copper is more resistant to corrosion by non-oxidizing acids, alkalis and seawater, but aluminum is more resistant to corrosion than copper in the atmosphere, weak acid and other media.
3. Easy processing and forming: Copper has moderate strength (200 ~ 360MPa), and its deformation resistance is greater than that of aluminum but much smaller than that of steel and titanium. Copper has good plasticity and can withstand large deformation of hot and cold pressure processing, such as rolling, extrusion, forging, stretching, stamping, bending, etc. The deformation degree of rolling and stretching can reach more than 95% without intermediate annealing and other heat treatment.
4. Color: Pure copper is simple and elegant purple (also known as bronze), copper alloys have various beautiful colors, such as golden yellow (H65 brass), silver white (nickel silver, zinc nickel silver), blue (aluminum bronze, tin bronze), etc., which are gorgeous or dignified and are very popular.
5. Antibacterial property: Copper can inhibit the growth of bacteria and other microorganisms. 99% of bacteria in water will be killed in a copper environment for 5 hours. This is very important for drinking water transmission, food utensils, marine engineering, etc.
6. Weldability: Copper is easy to weld by soft soldering, brazing, gas shielded arc welding and other methods. Phosphorus deoxidized copper containing a small amount of phosphorus has better weldability. Since copper has good thermal conductivity, copper welding requires high-power, high-energy beam welding facilities, and it is best to use gas protection. Spot welding is generally not recommended.
7. Plating: Copper has good plating properties. It can be electroplated with high-melting point metals such as nickel and chromium, or hot-dip plated with low-melting point metals such as tin and zinc.
Product Process and Classification
Copper-containing minerals are relatively common, and most of them have bright and eye-catching colors. These ores are roasted in air to form copper oxide CuO, and then reduced with carbon to obtain metallic copper. Objects made of pure copper are too soft and easy to bend. People have found that adding tin to copper can make a copper-tin alloy - bronze. The alloy of copper and gold can be made into various ornaments and utensils. Adding zinc makes brass; adding tin makes bronze.
1. Brass - copper-zinc alloy. The color changes from yellow-red to pale yellow as the zinc content increases. Brass has higher mechanical properties than pure copper. It will not rust or corrode under normal circumstances. It has good plasticity and is widely used in the machinery manufacturing industry to make various structural parts.
2. Bronze - copper-tin alloy (except zinc and nickel, all alloys with other elements are called bronze). It has good wear resistance, mechanical properties, casting properties and corrosion resistance. The tin content in the alloy generally does not exceed 10 %, too high will reduce its plasticity.
3. Cupronickel - copper-nickel alloy. It is divided into structural copper-nickel alloy and electrical copper-nickel alloy. Structural copper-nickel alloy has high mechanical properties and good corrosion resistance. Electrical copper-nickel alloy generally has special thermoelectric properties. The famous industrial manganese copper, constantan and copper are manganese cupronickel with different manganese contents. They are indispensable electrical materials for manufacturing precision electrical measuring instruments, rheostats, thermocouples, electric heaters, etc.
Construction and installation nodes
The processing and use of copper has a history of thousands of years. The application of copper in architecture can be summarized into two major systems: copper art and curtain wall products.
Copper art is a decorative copper art investment, including copper doors, screen murals, handrails, etc. in buildings. These decorative works are mainly made by professional copper art makers. It can be said that each piece has extremely high artistic value.
The use of copper curtain walls and roofs is similar to some metals such as stainless steel. There are also products such as copper-plastic composite panels and wind honeycomb panels on the market. If the project requirements are not high, a simpler method of using back reinforcement ribs or galvanized steel plate supports can be used to improve the flatness.
