Effect of Doping on Tungsten Copper Contacts (2/2)

Take W80-Cu20 tungsten copper contact as an example, were added 0.3% B, 2.0% Nb, 1.5% Ce, using high-speed photography to capture the arc without tungsten copper contact materials under high voltage and high-current interaction, and arc extinguishing process and calculation of the various stages of the amount of time, while taking advantage of the closure value oscilloscope recording discharging. It can be found that the arcing time of tungsten copper contacts added B and Nb is 1.5 times longer than the original contacts.

n addition, in the stable combustion, undoped tungsten copper contact has smaller arc root and the smallest volume of plasma cloud, which shows that higher density of arc plasma cloud increases the temperature of ionsphere; by comparison, doped tungsten copper contact has wider arc root, larger area of scatter and electron movements, which indicates the doping elements can play a role to split the arc. In summary, doped tungsten copper contact has longer arcing time, smaller chopping value, which can effectively disperse the arc and energy.

Next is anti-arc erosion test, which carried out under an inert gas welding, plasma cutting, select the same operating voltage and current, at regular intervals to contact the ablation mass loss were weighed, and observed by scanning electron microscopy of the surface morphology after ablation. By analyzing the experiment data, undoped tungsten copper contact has the maximum of ablation, the doping amount of contact the ablation of a certain percentage of the different constituent elements are significantly reduced. This is due to electrical breakdown occurs in the Cu-rich region, the arc aggregation and localized melting in the region and causing splashing liquid copper in undoped contacts; And after the addition of Nb and B to improve the distribution of the statue, so that small and uniform distribution of the copper phase in the process of arc arcing does not occur in the Cu-rich region, but evenly distributed over the surface, so as to effectively prevent the arc energy centralized, local ablation lead to failure of the contact material.

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