W-Cu Thermal, Electrical Conductivity Comparison of Different Process (2/2)

While for tungsten copper (W-Cu) two phases heat sink material, it has lower coefficient of thermal expansion, which thermal expansion behavior is much more complex than a single-phase material. The experiment shows that t lower temperatures, tungsten-copper composite material showed a negative thermal expansion, but only when the temperature exceeds a certain value showed positive expansion. Tungsten copper sample coefficient of thermal expansion of injection molding and compression molding process under more stable than copper infiltration sample, the magnitude of change is smaller.

This is due to the phase change, as well as the internal organization of the reasons magnetic stretch, thermal expansion of the material will show some special law. By increasing the degree of constraint W phase at elevated temperatures in the expansion phase of Cu, thereby reducing the thermal expansion coefficient of tungsten copper composite material. In addition, since the difference of the coefficient of thermal expansion of the materials, tungsten copper composite material will produce complex stress inside, whose distribution will restrain the thermal expansion behavior.

As for the electrical conductivity, it was detected by eddy current method. When an alternating current is cut coil (also called probes) near the surface of a conductive material, since the coil alternating magnetic field, it has an effect on the material surface and near surface induced swirling current, which called the vortex. Materials and eddy currents generate their own magnetic field coil reacts, which is related to the size of the surface conductivity near the surface. Non-ferromagnetic conductive material can be directly detected by eddy current sensor. After testing found that the sample injection molded tungsten copper has the highest conductivity, reaches 37.43%IACS, which is higher than molding sample (29.85%IACS) and infiltrated sample (33.18%IACS).

• < Prev
• Next >