Silver plated copper wire is a kind of thin wires which is silver plated low oxygen or oxygen free copper wire stretched by wire drawing machines.
The low oxygen copper rod and oxygen free copper rod have special characteristics due to different manufacturing methods.
The oxygen content of cathode copper for producing copper rod 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 in commonly 200 (175) to 400 (450)ppm, therefore Oxygen enters copper when copper is liquid,but the oxygen free copper rod made by up-cast method is opposite. After the oxygen was holding in liquid copper for some time, it was reduced and removed. Generally, the oxygen content of such rods is below 10-50ppm, and the lowest is 1-2ppm. Organizationally, in low oxygen copper, the oxygen exists in the form of copper oxide near the grain boundary.This is common for low oxygen copper rods but rare for oxygen free copper rods. The presence of copper oxide at grain boundaries in the form of entrained impurities has a negative effect on the toughness of the material. The oxygen content of free oxygen copper is very low, so the structure of such copper is uniform and the single-phase structure is favorable for toughness. Porosity in oxygen free copper rods is uncommon, while in low oxygen copper rods is a common defect.
The difference between the hot rolling structure and the casting structure.
The structure of the low-oxygen copper rod belongs to the hot-processed structure due to the hot rolling process. The original casting structure has been broken, and there has been the form of recrystallization when the diameter of the rod reaches 8mm. While the oxygen-free copper rod belongs to the casting structure, and its grain size is coarse, which is the inherent reason for the higher temperature of the recrystallization of the oxygen-free copper and the need for higher annealing temperature. Because the recrystallization occurs near the grain boundary, the grain structure of the oxygen-free copper rod is coarse, and the grain size can even reach several millimeters, so the grain boundary is less. Even if it is deformed by pulling, the grain boundary is still less than that of the low-oxygen copper rod, therefore, higher annealing power is required. The requirement for successful annealing of oxygen-free copper is: the annealing power of the first annealing when the rod is pulled, but the line of the structure has not yet been cast should be 10-15% higher than that of low-oxygen copper in the same situation. After continuous drawing, there should be enough allowance for the annealing power in the later stage and different annealing processes should be implemented for the actual difference between low-oxygen copper and oxygen-free copper, so as to ensure the softness of the wires in articles being processed and finished products wire.
Post time: Apr-03-2020