Fiber-structure Tungsten Copper Contact (2/2)

Copper in the molten state infiltrated in pores of tungsten skeleton by capillary forces, thereby connected to each other and form a dense material integrally. The advantage of using this method is that tungsten wire can distribute uniformly and copper wire can effectively induce. Since the most difficult to achieve tungsten copper contact with fiber-structure is how to make the fibers uniformly distribute in the matrix, whose distribution will affect the final properties directly. The weaving process can control tungsten wire to adjust the spacing between fibers. In addition, the distribution of copper wire at a high temperature infiltration, which presents the liquid copper supplement, under the action of surface tension, integration can reduce the surface area, prompting tungsten copper contact materials densification.

Tungsten wire diameter, infiltrated temperature and time all have an effect on the process. It uses tungsten fiber to take place of tungsten powder of conventional PM. Too large granularity of tungsten powder will have segregation and appear large area Cu-rich region, the binding force between the tungsten particles is also poor; too small granularity will prone to accumulate, leading to difficult to form a passage between the capillary and even hinder the formation of closed-cell infiltration were, so that the anti-arc erosion capacity decreases dramatically.

Fiber-structure has straight route so its density is higher after infiltration. But with the decreasing fiber diameter, it easily to form when copper was infiltrated pointed or wedge-shaped space, and solidification resistance is also large so that the defect forms. In addition, infiltration temperature has an optimum range, below the temperature which the sintered skeleton strength decreases, and the extension of sintering time, decrease the efficiency and increase energy consumption; the high temperature which the copper was in favor of lowering the viscosity of infiltration, but on the other hand the surface tension of liquid copper is reduced, and has an adverse effect on infiltration.

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