Oxidation
Technical reasons: In the past, most domestic manufacturers used general-purpose copper rods, and the copper content could reach 99.95. However, even today, there are still such problems in copper. O. The reason is that copper itself is not oxygen-free copper. During the processing process, the surface of copper will inevitably come into contact with air and oxidize. Nowadays, the country has introduced advanced oxygen-free copper production technology, as well as domestically developed oxygen-free copper production technology, so that the entire copper wire industry uses oxygen-free copper. This has undoubtedly greatly improved the blackening of copper wires. question. However, due to the processing of the copper rod, especially the application of the toughening process and the poor storage conditions of the finished copper wire core, the copper wire itself will still be slightly oxidized.
Material issues of the insulation layer: Insulating paint can be divided into five categories: impregnating paint, enameled wire paint, covering paint, silicon steel sheet paint, and anti-corona paint. Among them, impregnating paint is used to impregnate motors and electrical coils. Impregnating paint can fill the gaps and micropores in the insulation system, form a continuous paint film on the surface of the impregnated object, and bond the coils into a strong whole, effectively improving the integrity, thermal conductivity, and moisture resistance of the insulation system. properties, dielectric strength and mechanical strength.
Secondly, it also plays a role in heat dissipation. If the insulating paint is soaked, the dried coil can be regarded as a whole, and the heat of the inner and outer layers can be easily conducted, thereby dissipating heat. At present, my country's impregnating varnish and insulating oil production technology, preparation methods, and patented formula technical data are still relatively backward. The impregnating varnish produced and processed basically only has a short-term effect, and will fall off and fail over time. .
Usage problems: In the process of using coil copper wires, we often encounter such problems - collision and friction, slow flushing, a large amount of moisture in contact with the coil, and the use of waste engine oil for lubrication, resulting in scratches on the conductor surface. Residues and damage to the insulation layer cause oxidation of the conductor during subsequent processing.
Copper wire annealing process: Copper wire annealing refers to a metal heat treatment in which the copper wire is slowly heated to a certain high temperature, maintained for a period of time, and then cooled at a corresponding speed. Copper wire annealing can reduce the hardness, improve machinability, eliminate residual stress, stabilize dimensions, reduce deformation and crack tendencies, refine grains, adjust the structure, and eliminate structural defects. However, once the temperature is higher than 50°C during the production process, the stipulated pumping time is insufficient, the SO2 content is high, and the impure protective gas will cause insufficient annealing, and the copper wire will easily turn black after a period of time.
The reason for the blackening of the coil copper wire is caused by many factors, not only the above four factors, but also the state of the copper wire itself, the coil processing technology, the vulcanization process, and the coil's There are many factors such as structure, formula, coil production environment, etc.
Some metals are easily oxidized when left in the air for a long time. It is recommended to place pure copper in a dry and sunny place.