What is purple copper?
Purple copper, also known as red copper, is named after its purple red color. Generally, we call purple copper pure copper, but this is not accurate because strictly speaking, pure copper should theoretically have a copper content close to 100%. Purple copper is a relatively pure copper, but it cannot be completely equivalent to pure copper.
Purple copper is oxygen-containing, also known as oxygen-containing copper. The copper content of purple copper ranges from 99.5% to 99.99%. Purple copper has good conductivity and thermal conductivity, excellent plasticity, and is easy to process by hot pressing and cold pressing. It is widely used in the manufacturing of products such as wires, cables, electric brushes, and special copper for electrical discharge that require good conductivity.
The main grades of purple copper are T1, T2, and T3.
T1: Copper content above 99.95%, total impurities not exceeding 0.05%.
T2: The copper content is above 99.90%, and the total impurity content does not exceed 0.1%.
T3: The copper content is above 99.7%, and the total impurity content does not exceed 0.3%.
In addition, there are also grades such as C11000 in international standards. C11000 also has a high copper content, with a general copper+silver content of ≥ 99.90%.
What is oxygen free copper?
It is generally believed that oxygen free copper is pure copper that does not contain oxygen or any deoxidizers or residues; But in reality, it still contains very trace amounts of oxygen and some impurities, just very trace amounts! According to the standard regulations, the oxygen content should not exceed 0.003%, the total impurity content should not exceed 0.05%, and the purity of copper should be greater than 99.95%.
Therefore, oxygen free copper has higher conductivity and thermal conductivity, as well as better corrosion resistance and processing performance due to its extremely low oxygen content. Oxygen free copper is mainly used for components of electric vacuum instruments, such as busbars, conductive strips, waveguides, coaxial cables, vacuum seals, vacuum tubes, and components of transistors. Oxygen free copper has excellent processing performance and is suitable for fine processing. Oxygen free copper can be considered a special type of purple copper.
The main grades of oxygen free copper are: TU1 TU2,C10100,C10200.
TU1: Purity reaches 99.97%, oxygen content is not greater than 0.003%, and total impurity content is not greater than 0.03%. This oxygen free copper has a very high purity, excellent conductivity, thermal conductivity, corrosion resistance, and processing performance, without hydrogen embrittlement phenomenon. It is a high-quality copper material commonly used in applications that require high material purity and performance, such as electronics, electrical and other fields.
TU2: The copper content is greater than 99.95%, the oxygen content is not greater than 0.003%, and the total impurity content is not greater than 0.05%. TU2 oxygen free copper also has good conductivity, cold and hot processing performance, and welding performance. It has excellent malleability and is often used in the production and processing of environmental components and equipment with conductivity and ductility requirements, such as conductive bars, waveguides, electrode materials, etc.
C10100: Typically with a copper content exceeding 99.99% and an oxygen content below 0.001%. This is a high-purity oxygen free copper material with excellent conductivity and thermal conductivity, corrosion resistance, low porosity, and excellent formability. It is widely used in industries such as electronics, aerospace, automotive manufacturing, and transmission machinery.
C10200: Copper content ≥ 99.95%, total impurities ≤ 0.05%. Can be used for electric vacuum devices and instruments, meters, etc.
The difference in appearance between the two:
In terms of color
Purple copper: usually presents a purple red color, which is the reason for its name. The color is relatively bright and has a certain glossiness. Due to its easy oxidation in the air, a dark red or dark black copper oxide film may gradually form on its surface, but the overall purple red background can still be seen.
Oxygen free copper: Its appearance is generally a relatively pure copper color, close to silver white or light yellow. Due to its extremely low oxygen content, it is relatively stable in air and has a much slower oxidation rate than copper. Therefore, the surface color changes less and can maintain a bright metallic color for a longer period of time.
On the surface smoothness
Purple copper: Due to its relatively soft nature, scratches and abrasions are prone to occur during processing and use, which may affect the surface smoothness to some extent. The surface of oxidized copper may appear rough and lose some of its metallic luster.
Oxygen free copper: usually has a high surface finish, appearing smooth and delicate. Because oxygen free copper has high purity and relatively uniform material, it is easier to obtain better surface quality during processing.
Note: Distinguishing between oxygen free copper and purple copper by appearance is not an absolutely accurate method, as the appearance of copper materials may be affected by various factors such as processing technology, surface treatment, and degree of oxidation. In practical applications, to accurately distinguish, other methods such as chemical analysis and physical property testing can also be combined.
Difference in strength and hardness:
Purple copper: relatively low strength, low hardness, and soft texture. This makes copper prone to deformation during processing and use. For example, when making some thin-walled parts, it is necessary to consider the strength and hardness of the copper to avoid deformation or damage during use.
Oxygen free copper: After special treatment, it has relatively high strength and greater hardness than copper. This makes oxygen free copper more advantageous in situations where it needs to withstand certain pressure and wear. In the aerospace field, the high strength and hardness of oxygen free copper can meet the strict requirements of materials for aircraft.
In terms of corrosion resistance, oxygen free copper has better corrosion resistance than copper.
Difference in resistivity:
Copper: The resistivity at 20 ℃ is approximately 0.01851 Ω· mm ²/m (or 1.851 × 10 Ω· m).
Copper has good conductivity, second only to silver among all metals, and is an important conductive material. But its conductivity is slightly lower than that of oxygen free copper. For example, in the electrical field, copper wires can transmit current well, but in some situations where high conductivity is required, they may not be able to meet the demand.
Oxygen free copper: The resistivity at 20 ℃ is approximately 0.0171 μ Ω· m (or 0.0171 × 10 ⁻⁶Ω· m).
Oxygen free copper has a higher conductivity, generally reaching over 100% IACS (International Annealed Copper Standard), much higher than copper. This gives oxygen free copper unique advantages in fields such as electronics and electrical engineering. In high fidelity audio cables, oxygen free copper can ensure high-quality transmission of audio signals and reduce signal loss.
The difference in thermal conductivity:
Purple copper: It has good thermal conductivity and is commonly used in the production of heat exchangers, radiators, and other thermal conductivity equipment. For example, in some industrial equipment, the thermal conductivity of copper can effectively transfer heat and improve the efficiency of the equipment.
Oxygen free copper: Its thermal conductivity is slightly higher than that of copper, and it performs better in some situations where high thermal conductivity is required. For example, in high-end electronic devices, the high thermal conductivity of oxygen free copper can help dissipate heat and ensure stable operation of the equipment.
Differences in usage and price:
Copper is widely used in general electrical, electronic, and industrial fields.
Oxygen free copper performs well in high-frequency signal transmission. Oxygen free copper can be used to make high-end wires and cables, high-end electronic products, vacuum tubes, and other products that require high conductivity and signal transmission, as well as applications in communication, aerospace, and other fields that require strict material performance.
Oxygen free copper is indeed superior to ordinary purple copper in certain performance aspects, but it cannot be generalized that oxygen free copper is more high-end than purple copper. Depending on the usage scenario and requirements, each has its own advantages in different applications.
In a broad sense, oxygen free copper can be classified as a copper material with specific properties and applications within the broad category of purple copper. So, in terms of production costs, the production process of oxygen free copper is relatively complex, and the cost is usually higher than that of purple copper. Generally, oxygen free copper can be thousands of yuan more expensive than purple copper per ton.
