Effect of powders and heat treatments on electrical conductivity of HPCS and LPCS Cu coatings

Cold spraying is a suitable method of producing pure and dense copper coatings, e.g., for applications where good electrical conductivity plays an essential role. Basically, copper as a material is known for its excellent thermal and electrical conductivity. Cold-sprayed copper coatings can also possess high electrical conductivities due to oxide-free and porosity-free structures. Such microstructures are formed by particle impacts in a solid state with high velocities (high kinetic energy) and coating structures are built up due to a high degree of plastic deformation. The present study shows the electrical conductivity data of various high-pressure cold-sprayed (HPCS) Cu and low-pressure cold-sprayed (LPCS) Cu and Cu+Al2O3 coatings. In addition, the effect of powder characteristics, i.e., particle size and particle morphology, and compositions, i.e., pure Cu and Cu with Al2O3 additions, and heat treatments (400ºC, 2 h) on electrical conductivity is investigated. Voltages were measured
with a four-point measuring system and thereafter, resistances and further electrical resistivities and electrical conductivities were calculated. In addition, electrical conductivities were measured using an eddy-current measuring system. The results are presented as IACS% (International Annealed Copper Standard) values. Generally, conductivity is essentially affected by the microstructural details of the coatings. Higher denseness led to the lower resistivity and thus, to higher electrical conductivity. Additionally, the manufacturing method of the coating had an influence on the electrical conductivity: HPCS coatings had a higher electrical conductivity than
LPCS coatings had. Furthermore, heat treatments significantly improved the electrical conductivity properties of the coatings.