Wear resistance of laser-sintered gold-nickel composite film for electrical contacts

Materials for electrical contacts not only require good electrical properties but must also satisfy requirements for wear resistance, low-friction coefficient, and corrosion resistance. To improve wear resistance, composite plating with dispersed nanoparticles on a metal matrix has been developed. The noble metal processes of dispensing gold nanoparticle paste with dispersed nickel nanoparticles on a phosphor-bronze substrate followed by sintering with an infrared laser to form a laser-sintered gold-nickel composite film are described. Tests for adhesion, wear resistance, and electrical property of the laser-sintered film lead to the following conclusions: (1) an infrared laser enables the formation of a gold film containing dispersed nickel nanoparticles in an air atmosphere; (2) the laser-sintered film possesses an equally good adhesion to the substrate, wear resistance and electrical property as an electroplated one; (3) as nickel content increases, the distribution of nickel nanoparticles deposited on the gold composite film becomes uneven. The use of nickel nanoparticles with 0.5 mass% dispersion results in a relatively uniform distribution; (4) although contact resistance of the 0.5 mass% nickel-content film is slightly greater than that of a pure gold one, a low contact resistance of less than 100 mΩ is maintained, as shown by a reciprocated-sliding test consisting of 3000 repetitions; (5) the proposed on-demand method has considerable advantages as it takes just over 1 min to form a 0.3μm-thick film, and material consumption is reduced by a factor of ten in making a contact area with a diameter of 0.8 mm.