What Is Copper:Types, Uses And Applications

Copper is such an element that has so much to amaze people with facts and has such a huge role in day-to-day life, from electrical circuits to household items. No other material can match this versatility. This article covers what copper means, its properties, and why it is of paramount importance across industries.

What Is Copper?

Copper is a highly ductile and malleable metal renowned for its excellent conductivity of heat and electricity. It also exhibits remarkable resistance to both chemical and microbiological corrosion. Found in various forms within the Earth’s crust, copper occurs in sulfide deposits like chalcopyrite, bornite, pentlandite, and cobaltite; carbonate deposits such as azurite and malachite; silicate deposits like chrysocolla and dioptase; and as natural “native” copper in its pure form. In addition, copper naturally occurs in humans, animals, as well as plants. All organic life forms have been evolving in copper-containing environments. As a nutritionally essential element, copper plays an imperative role in health sustenance. The continued performance of life is based upon copper.

History Of Copper

Archaeological evidence reveals that copper was among the earliest metals utilized by humans, with its use dating back over 10,000 years for making coins and ornaments in the Near East. During the Chalcolithic Period, a prehistoric era named from the Greek word chalkos (meaning copper), humans learned to extract and work copper into tools and decorative objects. By the 4th to 3rd millennium BCE, copper mining was underway in Spain’s Huelva region. The innovation of alloying copper with tin to produce bronze, around 2500 BCE, ushered in the Bronze Age.

In Israel’s Timna Valley, copper was supplied to Pharaohs, as recorded in an Egyptian papyrus detailing copper’s use for treating infections and purifying water. Cyprus became a major supplier of copper for the Phoenicians, Greeks, and Romans, and the Latin word “Cyprium,” meaning “metal of Cyprus,” eventually evolved into “copper.” In Aristotle’s era, Greeks were familiar with brass as a valuable copper alloy.

Pre-Columbian cultures of South America also used copper, as did the cultures of the Maya, the Aztecs, and the Incas in their work together with gold and silver; during the Middle Ages the art of copper and bronze was well developed in China, India, and Japan.

The late 18th and early 19th centuries saw transformative discoveries and inventions in electricity and magnetism by scientists like Ampere, Faraday, and Ohm, driving the Industrial Revolution and ushering copper into a new era of innovation. Today, copper continues to meet societal needs, with its applications evolving over time. One modern example is the development of copper chips in the semiconductor industry, showcasing its ongoing technological relevance even after 10,000 years of use.

Physical Properties Of Copper

Copper is one of the oldest metals known to mankind, sharing Group 11 of the periodic table with silver and gold-the so-called “shining family.” It has high ductility and an excellent conductivity; hence, it is highly valuable in industries and day-to-day life. Now, let’s enter the wonderful world of copper.

Attractive Color And Malleability

Copper bears a reddish-orange color, which is unique from most metals. This is because the energy gap between its 3d and 4s electron orbitals corresponds to the wavelength of orange light. It is also highly ductile, which allows it to easily be drawn into fine wires used in a wide range of industrial and household applications. The low hardness of single-crystal copper has been attributed to weak metallic bonds with little covalent character, which confer exceptional softness and high ductility. However, when a fine-grained polycrystalline structure is formed in copper, defects such as grain boundaries restrict material flow under pressure and hence increase its hardness. This explains why copper products are generally harder and more practical for use.

Superior Conductivity And Thermal Properties

Copper features superior electrical and thermal conductivity. It has an electrical conductivity of 59.6×10⁶ S/m, the second highest of all metals, after only silver. At ordinary temperatures, the motion of electrons in metals is practically impeded by scattering through lattice vibrations, and the softness of copper reduces such scattering, giving it remarkable conductivity. Its thermal conductivity is equally impressive at 401 W/(m·K), making it quite suitable for wires, cables, and heat sinks. Most importantly, copper’s maximum permissible current density in open circuits is 3.1×10⁶ A/m² beyond which the overheating of copper takes place. Besides, the galvanic corrosion in copper in contact with other metals must be cautiously handled by the engineers for good serviceability.

Unique Appearance And Decorative Appeal

Copper is among the few colored metals that occur in nature, in company with yellow gold, golden cesium, and blue osmium. Its distinctive color combines with its other attributes in making it a very popular commodity in decorative uses. An oxide layer forms on its surface in contact with the air, which obscures any brilliance and imparts the characteristic reddish patina to ancient copper pieces of work.

Varied Importance To Industry And Life

Copper is indispensable in industry due to its incomparable conductivity, thermal properties, and toughness; it forms the very base of electrical and mechanical manufacture. Its distinctive color and softness also make it highly valued in art and decoration. Even though copper has been used for over 10,000 years, its uses are still developing further, with copper chips being developed in the modern semiconductor industry, showing how relevant and innovative it still is.

Chemical Properties Of Copper

Copper is not only a pretty metal, but it has some very interesting chemical properties, too. Ever wondered why copper pipes turn green with time? That’s because of its reaction with oxygen, forming a protective layer. These chemical properties make copper strong and dependable in all kinds of uses.

Reaction With Oxygen

Copper does not react with oxygen in dry air. However, in moist conditions, it slowly forms a black layer of copper(II) oxide, CuO. This is a protective layer that can prevent further corrosion, under certain conditions.

Reaction With Acids

With Nitric Acid:

Copper reacts with concentrated nitric acid to form copper(II) nitrate, Cu(NO₃)₂, water, and nitrogen dioxide, NO₂. When reacting with dilute nitric acid, copper yields copper(II) nitrate, water, and nitrogen monoxide, NO.

With Sulfuric and Hydrochloric Acids:

Copper does not react with dilute sulphuric acid or hydrochloric acid under normal conditions since it is below hydrogen in the reactivity series and hence cannot displace hydrogen ions from these acids.

Reaction With Salt Solutions

Copper undergoes displacement reactions with some of the soluble salt solutions. Such as solution of silver nitrate or ferric chloride.

These reactions occur in this manner because copper, while more reactive than silver but less than iron, displaces some metal ions that might be present in a solution.

Reaction With Alkaline Solutions

Because the reactivity of copper with hydroxide ion is comparatively low, its reaction with alkaline solutions – such as sodium hydroxide or potassium hydroxide – is zero.

The chemical behavior of copper proves its position as a moderately reactive metal. It does not oxidize in dry air but does so in moist conditions. It reacts with nitric acid to form nitrates but is unreactive with weaker acids and alkaline solutions. The fact that copper can undergo displacement reactions with some salts corroborates its middle position in the reactivity series. This makes copper versatile for many uses in both chemical and industrial processes.

What Is The Process Of Producing Copper?

Geologists are specially trained to find traces of mineral deposits, like nature’s detectives, in pursuit of any geological anomaly that might indicate underground treasures. For these treasures to turn into copper mines, all conditions-geological, economic, environmental, and legal-must be just right for mining to take place without hitches.

Do you know the three “magic” methods of copper mining? Once a deposit is discovered, copper ore extraction begins. The main mining methods include:

• Surface Mining: This is the most common method in the world, whereby digging into the ground is done to disclose copper ore.
• Underground Mining: This involves tunneling beneath the surface, suitable for deposits buried deep underground.
• Leaching: This technique resembles chemical magic, extracting copper from ore by “washing” it out.

The journey from ore to “shiny copper” is a fairly simple one. After extraction, the ore undergoes crushing and grinding, followed by a flotation process to isolate the copper concentrate. This method resembles sifting gold from sand, resulting in a concentrate that generally contains around 30% copper, though it can sometimes exceed 40%.

The smelting process typically begins with a roasting stage, transforming copper ore into “matte” with a copper content of 50-70%. The molten matte is then treated in a converter, resulting in blister copper with a purity of 98.5-99.5%.

Next comes fire refining of blister copper or its melting and casting into anodes for electrolytic refining. This process yields refined cathode copper with a purity of at least 99.99%, essentially making it pure copper.

Different Types Of Copper

Many believe that copper exists in only one form, but in fact, there are various types. For example, alloyed copper includes several variations: brass, a blend of copper and zinc; white copper, an alloy of copper and nickel; and bronze, which combines copper with elements other than zinc or nickel, such as tin (tin bronze) or aluminum (aluminum bronze). Additionally, red copper, distinguished by its extremely high copper content, has less than 1% of other impurities.

Pure Copper

Pure copper is a rose-red metal. After the formation of a copper oxide film on the surface, it becomes purple; therefore, industrial pure copper is generally called red copper or electrolytic copper. The density is 8~9g/cm?, and the melting point is 1083℃. Pure copper has excellent electrical conductivity and is widely used for making wires, cables, brushes, etc. Besides that, it has excellent thermal conductivity and is normally used for the production of magnetic instruments and meters which need protection from magnetic interference, such as compasses and aircraft instruments. In addition, the plasticity is very great and it is easy to hot-press and cold-process, can be manufactured in tube, rod, line, strip, plate, foil and other copper materials.

Pure copper products can be produced through smelting or processing. Based on composition, Chinese copper processing materials are categorized into ordinary copper (T1, T2, T3, T4), oxygen-free copper (TU1, TU2, and high-purity vacuum oxygen-free copper), deoxidized copper (TUP, TUMn), and special copper containing trace alloy elements such as arsenic copper, tellurium copper, and silver copper. With electrical and thermal conductivity second only to silver, pure copper is extensively used in manufacturing conductive and heat-dissipating equipment. Copper also exhibits excellent corrosion resistance in environments such as the atmosphere, seawater, non-oxidizing acids like hydrochloric and dilute sulfuric acid, alkalis, salt solutions, and organic acids like acetic and citric acid, making it a key material in the chemical industry. Furthermore, copper boasts good weldability and can undergo cold and hot plastic processing to create various semi-finished and finished products.

Brass

Brass, an alloy of copper and zinc, is one of the most versatile materials. The simplest form, a binary combination of these metals, is known as simple or ordinary brass. By varying the zinc content, brass can be engineered to exhibit different mechanical properties. Higher zinc levels enhance the alloy’s strength but reduce its plasticity. In industrial settings, the zinc content in brass is usually kept below 45%, as exceeding this threshold can cause brittleness and compromise performance. Brass is broadly categorized into two primary types: casting brass and brass designed for pressure processing.Brass is divided into:

Common brass is an alloy of copper and zinc. When the zinc content is less than 39%, it fully dissolves into copper, forming a single-phase α structure, also known as single-phase brass. This type of brass exhibits good plasticity and can withstand both hot and cold pressure processing. However, when the zinc content exceeds 39%, the alloy develops two phases: α and a copper-zinc-based β solid solution, referred to as duplex brass. The presence of the β phase reduces plasticity but enhances tensile strength, making duplex brass primarily suitable for hot pressure processing.

Brass is represented by the code “H+number,” where “H” stands for brass, and the number indicates the copper mass fraction. For instance, H68 signifies brass containing 68% copper and 32% zinc. Cast brass is prefixed with a “Z,” such as ZH62. Alloys like H90 and H80, which are single-phase and golden yellow, are often referred to as “gold brass” and are commonly used for plating, decorations, and medals. H68 and H59 are duplex brass alloys, widely applied in the structural components of electrical equipment, including bolts, nuts, washers, and springs. Typically, single-phase brass is used for cold deformation processing, while duplex brass is better suited for hot deformation processing.

Superconductivity And Cryogenics

In all materials except semiconductors, electrical resistance is lowered with decreasing temperature. In a few materials, at very low temperatures, the electrical resistance becomes zero. This is called superconductivity. The temperature at which this occurs is called the critical temperature for the material in question, and the critical temperature is different for different materials. The discovery of superconductivity has opened completely new avenues for the applications of electricity.

In the case of zero resistance, even a very small applied voltage can produce extremely large, theoretically infinite currents, which in turn can yield incredibly huge magnetic fields and forces. Besides, no voltage drop and no loss of energy occur when the current passes through a superconductor. The practical applications of superconductivity have great potential to revolutionize industries and everyday life, and for this reason, it is of great interest. But in the case of most conventional metals, superconductivity is only attained at temperatures close to absolute zero (-273°C), which is very hard to achieve in engineering applications.

Recently, superconducting alloys have been fabricated with comparatively higher critical temperature than that of their parent pure metals. For example, the alloy Nb₃Sn has a critical temperature of 18.1 K. However, these applications heavily depend on copper.

Superconducting alloys must work at ultra-low temperatures achieved by the liquefaction of gases. The liquefaction temperatures of helium, hydrogen, and nitrogen are 4 K (-269°C), 20 K (-253°C), and 77 K (-196°C), respectively. Copper retains excellent ductility and plasticity even at such low temperatures, becoming an indispensable material for structural components and pipeline systems in cryogenic engineering.

Moreover, superconducting alloys such as Nb₃Sn and NbTi are brittle and difficult to work into useful shapes. Copper is used as a cladding material to hold and support these alloys. Currently, superconducting materials are being used to fabricate high-powered magnets, including those in medical diagnostic MRI machines and in high-field-strength magnetic separators used in mining.

Aerospace Technology

Copper and its alloys are used in many of the vital parts of rockets, satellites, and spacecraft outside of the microelectronic controls, instruments, and equipment.

For example, the combustion chamber and thrust chamber linings in rocket engines are made from copper alloys because of their high thermal conductivity for cooling to maintain the temperature within allowable limits. The lining of the combustion chamber in Ariane 5 rockets is fabricated from a copper-silver alloy that is engineered with 360 cooling channels inside the liner. During rocket launches, liquid hydrogen circulates through these channels for cooling.

Copper alloys are the most common materials in satellites for load-carrying structures. Added element copper alloys are also widely used in satellites’ solar wing panels.

High-Energy Physics

Unveiling the mysteries of matter’s structure is a fundamental scientific pursuit with profound implications for humanity. A prime example of such breakthroughs is the utilization of atomic energy. Modern physics has revealed that the fundamental building blocks of matter are not molecules or atoms but much smaller particles—quarks and leptons, which are billions of times smaller.

Research into these subatomic particles very often requires enormously high reaction energies, several hundreds of times higher than those created in a nuclear explosion-a field of study commonly referred to as high-energy physics. Such high energies are achieved in one of two ways:

accelerating charged particles over long distances using powerful magnetic fields to collide with a fixed target (high-energy accelerators),

colliding two streams of particles moving in opposite directions (colliders).

Such strong magnetic fields must be generated at long distances, and the magnetic channels are made using steel windings. In the case of controlled thermonuclear fusion devices, such similar structures are also required.

To avoid such high heat generation and temperature rise caused by the high currents passing through these magnetic channels, the structure is made from hollow, specially shaped copper rods. This allows the cooling media to pass through the structure and effectively dissipate the heat generated.

What Are The Different Forms Of Copper?

Copper is ductile and thus can be cast into many forms for innumerable uses. Sheets, wires, pipes-the list goes on and on, with each form important in industries and homes. Let’s look at the versatility of copper material and its many forms.

Copper Tubes

Copper tubes are widely used in plumbing, heating, and refrigeration system installations. They are highly favored because they resist corrosion and assure durability for long performance in a wide range of applications.

Copper Rods

It comes in two major types: brass rods and pure copper rods. It is known for its good machinability and high conductivity. These are in huge application, ranging from electrical and mechanical to industrial applications.

Copper Wires

Copper wires are mainly used in making electrical wires and cables. The excellent electrical conductivity of this material makes it one of the most usable materials in electrical engineering and transmission systems.

Copper Sheets

These are preferred for roofing and façade cladding because of their stability and low maintenance. Other usages include the manufacture of various electrical components.

Copper Strips

The copper strips mainly find their application in the electrical components, connectors, and other precision applications manufacturing. The strips ensure very good conductivity, thermal performance, and corrosion resistance, thus satisfying the exacting requirements of modern electronic and industrial systems.

Copper Materials In CNC Machining

Copper and its alloys are widely used in CNC machining for their excellent electrical and thermal conductivity, corrosion resistance, and machinability. Common copper materials include pure copper (C11000), brass (copper-zinc alloys), bronze (copper-tin alloys), and copper-nickel alloys (CuNi). Pure copper is valued for its high conductivity and is thus perfect for electrical components, but it is soft and can work-hardened in a very short time, requiring special care. Brass is noted for good machinability and is thus widely used in precision parts, such as gears and fittings. Bronze, being tough and resistant to wear, finds application in bushings and bearings, while copper-nickel alloys are chosen because of their corrosion resistance in marine and chemical applications.

The major problem with copper when machining is work hardening, which makes the material hard to cut, thus resulting in heavy tool wear. Work hardening may be reduced by use of slower speeds, lubrication, and cooling. In general, brass alloys give good machinability, requiring less effort and giving better finishes. However, harder alloys like bronze and copper-nickel require special tooling with slower speeds and increased cooling to avoid overheating, which would also lead to clean cuts. Free-cutting brasses containing lead are more machinable and suitable for large-volume applications.

One major problem while machining copper is work hardening, that prevents one from getting clean cuts, and leads to tool wear. To offset this, the machinist should use slower speeds and cool and lubricate the part properly. Copper-nickel alloys are much harder and may well require carbide tools and slower speeds due to severe tool wear. Alloys that include zinc or lead, like brass, also show excessive tool wear, and so appropriate tools, such as carbide or coated ones, must be chosen. These can be minimized by adjusting the machining parameters and choosing the proper alloy.

Conclusion

Copper is one of the most conductive and versatile materials, having vital Cu chemistry. Its uses range from electrical wiring to decorative items, just about everything. The knowledge of types of copper, pure copper, and copper alloys helps industries in making better choices. With the advancement of technology, the role of copper in sustainable and innovative applications will keep on increasing, making it an indispensable copper metal.

Final Thoughts

As a professional with 15 years in the CNC machining service industry, I’ve seen firsthand how copper and its alloys are integral to a wide range of applications. Copper, known for its excellent conductivity, is commonly used in electrical components, heat exchangers, and mechanical parts. For example, in one of our recent projects, we worked on producing custom copper connectors for a power distribution system, where we had to ensure minimal work hardening during machining. Pure copper was ideal for conductivity but required slower cutting speeds and specialized cooling to maintain precision.

Brass, a more machinable copper alloy, is used in components like valves and gears. In another case, we produced brass parts for the automotive industry, ensuring smooth finishes with high machinability and minimal tool wear.At Ultirapid, we specialize in machining copper and its alloys to exacting standards. With years of experience, we offer efficient, high-quality solutions for various copper-based applications, ensuring precision, durability, and optimal performance.

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