| Type: | Copper Bars |
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| Application: | Air Condition or Refrigerator, Water Tube, Water Heater, Oil Cooler Pipe |
| Material: | Brass |
| Shape: | Round |
| Alloy: | Non-alloy |
| Color: | Golden |
| Samples: |
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| Customization: |
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c11000 Copper bar
c11000 copper pipe
c11000 copper plate
c11000 oxygen free copper
Pure copper without oxygen or any deoxidizer residue. But it actually contains very small amounts of oxygen and some impurities. According to the standard provisions, the oxygen content is not more than 0.003%, the total impurity content is not more than 0.05%, the purity of copper is greater than 99.95%.
Anaerobic copper products are mainly used in the electronics industry. Often made of oxygen free copper plate, oxygen free copper strip, oxygen free copper wire and other copper materials.
oxygen-free copper
According to oxygen content and impurity content, oxygen free copper is divided into one and two oxygen free copper. The purity of No. 1 oxygen-free copper is 99.97%, the oxygen content is no more than 0.003%, and the total impurity content is no more than 0.03%. The purity of No. 2 oxygen-free copper is 99.95%, the oxygen content is no more than 0.005%, and the total impurity content is no more than 0.05%.
Oxygen free copper has no hydrogen embrittlement phenomenon, high conductivity, good machining and welding properties, corrosion resistance and low temperature properties. The standard of oxygen content in different countries is not exactly the same, there are some differences.
OFC (oxygen free copper) : metallic copper with a purity of 99.995%. Generally used in audio equipment, vacuum electronic devices, cables and other electrical and electronic applications. Among them, there are LC-OFC (linear crystal oxygen free copper or crystal oxygen free copper) in the purity of more than 99.995% and OCC (single crystal oxygen free copper) : the highest purity, more than 99.996%, and is divided into PC-OCC and UP-OCC, etc.
Single-crystal oxygen-free Copper manufactured by UP-OCC technology (Ultra Pure Copper by Ohno Continuous Casting Process) has non-directional, high purity, corrosion resistance and extremely low electrical impedance, making the wire suitable for high-speed and high-quality signal transmission. [1]
The smelting of copper without oxygen
Strictly distinguish, anaerobic copper should be divided into ordinary anaerobic copper and high purity anaerobic copper. Ordinary oxygen-free copper can be smelted in power frequency induction furnace with iron core, while high purity oxygen-free copper should be smelted in vacuum induction furnace.
When the semicontinuous casting method is adopted, the refining process of melt in the melting furnace and the holding furnace can be free of time constraints. Continuous casting is different. The quality of liquid copper not only depends on the refining quality of melting furnace and holding furnace, but also depends on the stability of the whole system and the whole process.
In order not to pollute the melt, anaerobic copper smelting generally does not use any additives in the way of smelting and refining, the surface of the molten pool covered with charcoal and the resulting reducing atmosphere is the most commonly used melting atmosphere.
Induction furnace
The induction furnace for smelting copper without oxygen should be well sealed.
High quality cathode copper should be used as raw material for smelting anaerobic copper. High purity cathode copper should be used as raw material for smelting high purity oxygen free copper. If the cathode copper is dried and preheated before entering the furnace, it can remove the moisture or moist air that may be adsorbed on its surface.
The thickness of the charcoal layer covered on the surface of the molten pool in the furnace should be doubled than that of ordinary pure copper smelting, and the charcoal needs to be updated in time. Although charcoal mulching has many advantages, such as insulation, air isolation and reduction, it also has certain disadvantages. For example, charcoal is easy to absorb moist air, or even directly absorb water, which makes it possible to make a large amount of copper liquid absorption of hydrogen channels.
Charcoal or carbon monoxide can reduce cuprous oxide, but hydrogen is completely helpless. Therefore, charcoal should be carefully selected and calcined before being added to the furnace.
In the process of melting, transfer, heat preservation and the whole casting process, it is necessary to protect the melt completely. Many modern anaerobic copper smelting and casting production lines, not only melting, including the charge of drying preheating, transfer flow trough, pouring chamber and so on have taken a comprehensive protection.
Some modern large oxygen-free copper production lines take producer gas as the protective gas, and most of the gas producer takes natural gas as the raw material.
A method of manufacturing protective gas widely used abroad is: firstly, natural gas with relatively low sulfur content and 94% ~ 96% methane are burned with theoretical air, and hydrogen is removed by nickel oxide as the medium. The gas made is mainly composed of nitrogen and carbonate gas. Then, the carbonated gas is changed into carbon monoxide by heating charcoal, and an oxygen-free gas containing 20% ~ 30% carbon monoxide and the rest nitrogen is obtained.
In addition to producer gas, nitrogen, carbon monoxide or argon are also used as oxygen free copper melt protection or refining medium materials. [2]
Vacuum smelting
Vacuum smelting should be the best choice for high quality anaerobic copper smelting.
Vacuum melting can not only greatly reduce the oxygen content, but also the content of hydrogen and some other impurity elements.
Graphite crucible and high purity cathode copper or remelted copper which have been refined twice are used as raw materials for smelting in vacuum medium frequency coreless induction furnace. The furnace, along with the cathode copper, also includes flake graphite powder for deoxidation. In fact, the deoxidation is mainly through the graphite crucible material of the carbon. Carbon consumption, you can calculate, for example, 100 grams of carbon per kilogram of copper. Experience shows that the higher the oxygen content in molten copper at the beginning, the faster the initial deoxidation reaction.
Oxygen content and hydrogen content of anaerobic copper obtained by vacuum smelting can be lower than 0.0005% and 0.0001% ~ 0.0003%. In fact, only when copper is smelted and cast at a certain vacuum, it is possible to obtain castings completely free of oxygen and other gases, so the vacuum furnace used to produce copper in electronic pipes should have a vacuum degree of more than 10-6. [2]
Oxy-copper rod and anoxy-copper rod editing broadcast
Oxygen copper rod and oxygen - free copper rod have their own characteristics because of their different manufacturing methods.
1) About oxygen intake and removal and its presence
The oxygen content of cathode copper for copper rod production is generally 10 ~ 50ppm, and the solid solubility of oxygen in copper is about 2ppm at room temperature. Oxygen content of low oxygen copper rod is generally in 200 (175) ~ 400 (450) ppm, so oxygen into the liquid inhalation of copper, and on the contrary, oxygen in liquid copper to maintain a considerable time, is reduced and removed, usually the oxygen content of this rod are in 10 ~ 50ppm below, the lowest up to 1 ~ 2ppm, In terms of structure, the oxygen in hypoxic copper, in the form of copper oxide, exists near the grain boundary, which is common for hypoxic copper rods but rare for anaerobic copper rods. The appearance of copper oxide in the form of inclusion at grain boundaries has a negative effect on the toughness of the material. The oxygen in anaerobic copper is very low, so the structure of the copper is uniform and single-phase, which is good for toughness. Porosity is uncommon in anaerobic copper rods, but is a common defect in low oxygen copper rods.
2) The difference between hot rolling and casting structures
Low oxygen copper rod due to hot rolling, so its organization is a hot processing organization, the original casting organization has been broken, in the 8mm rod has recrystallization form, and anaerobic copper rod is a casting organization, grain coarse, this is why, anaerobic copper recrystallization temperature is higher, the inherent reason for higher annealing temperature. This is because, recrystallization occurs near the grain boundary, oxygen free copper rod grain coarse, grain size can even reach a few millimeters, so the grain boundary is less, even through the drawing deformation, but the grain boundary is relatively low oxygen copper rod or less, so the need for higher annealing power. The requirements for successful annealing of anaerobic copper are: the first annealing of the rod drawn, but not yet cast structure of the wire, the annealing power should be 10 ~ 15% higher than that of low oxygen copper in the same condition. After continuous drawing, in the later stage of annealing power should be left enough margin and low oxygen copper and oxygen free copper to effectively perform different annealing processes to ensure the softness of the product in process and the finished wire.
3) Inclusion, oxygen content fluctuation, surface oxide and possible differences in hot rolling defects
Compared with low-oxygen copper rod, the drawability of anaerobic copper rod is superior in all wired diameters. In addition to the above structural reasons, anaerobic copper rod has less inclusion, stable oxygen content, no defects that may be produced by hot rolling, and the thickness of surface oxide of the rod can reach 15A or less. In the process of continuous casting and rolling, if the process is not stable and the oxygen monitoring is not strict, the unstable oxygen content will directly affect the performance of the rod. If the surface oxide of the rod can be made up in the continuous cleaning of the post process, but the more troublesome is that there are quite a lot of oxides exist in the "subcutaneous", which has a more direct impact on the broken wire. Therefore, in the drawing of the micro-wire, ultra-fine wire, in order to reduce the broken wire, sometimes to take a forced way to the copper rod -- peeling, even the reason for the second peeling, The objective is to remove subcutaneous oxide.
4) The toughness of low oxygen copper rod and no oxygen copper rod is different
Both can be drawn up to 0.015mm, but the low-temperature oxygen-free copper in the low-temperature superconducting wire is only 0.001mm apart from each other.
5) From the raw material of the rod to the economic difference of the line.
High quality raw materials are required for the manufacture of anaerobic copper rods. Generally, drawing diameter > When the copper wire is 1mm, the advantage of low oxygen copper rod is more obvious, and the advantage of no oxygen copper rod is the drawing diameter < 0.5mm copper wire.
6) The wire making process of low-oxygen copper rod is different from that of anaerobic copper rod.
The wire making process of low oxygen copper rod can not be copied to the wire making process of no oxygen copper rod, at least the annealing process of the two is different. Because the softness of wire is deeply affected by the material composition, rod making, wire making and annealing process, it is not simple to say that the soft and hard of low oxygen copper or no oxygen copper. [3]
Related editorial broadcast
Copper has high electrical and thermal conductivity, good weldability, excellent plasticity and ductility, excellent cold working performance and non-magnetic properties. Dispersing oxygen-free copper overcomes the shortcomings of low yield strength after annealing and poor creep resistance at high temperature, and has the characteristics of high temperature, high strength and high thermal conductivity, which is highly valued by experts in electronic materials. Copper and its alloys have been widely used in the electronic industry. In vacuum electronic devices, oxygen free copper has been the first among the seven structural materials in this field.
Oxygen content is one of the most important properties of oxygen free copper. Because the amount of oxygen and copper is very small, oxygen in oxygen free copper actually exists in the form of Cu2O. At high temperatures, hydrogen diffuses through the copper at great speed, encounters Cu2O and reduces it, producing large amounts of water vapor. The amount of water vapor is proportional to the oxygen content of copper. For example, after annealing of 0.01% copper containing oxygen, 14cm3 water vapor will be formed in 100g copper. This water vapor cannot be dispersed through dense copper, so in the presence of Cu2O, there will be thousands of mpa of pressure, which will cause copper destruction, brittle cracking and loss of vacuum density. Therefore, oxygen content must be strictly limited.
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