ELECTRICAL CONTACTS FOR STRONG CURRENTS
MADE BY POWDER METALLURGY
It was tested to be produced electrical contacts for strong currents by
infiltration after sintering, because the final density is much higher (11.100
kg/m3) and porosity is much lower (10.85 %). The infiltration after sintering
variant contains the steps: powder mixture preparation (W – 52 mass % – 520 g,
Ni – 2 mass % – 20 g, Cu – 46 mass % – 460 g, zinc stearate – 0,7 mass % – 7
g), homogenization, pressing (4.5 MPa), sintering (730 and 780 oC) and
infiltration (the green part is layed down on an electrocorindon EC 120 bed,
then the Cu green is on top of it, 1100 oC). In this variant the green part density
is almost constant (s = 0.062), with an identical porosity of the first after the end
of the process (14,28 %). By infiltration the density increased drastically (at
10,832 kg/m3), but its variations were increased also (s = 0.174) and porosity
decreased (at 10.85 %). The attained density is not sufficient for electrical
contacts work (11,100 kg/m3), but it is closer. The final composition of the
electrical contact was: W – 48.69 mass %, Ni – 1. 87 mass % and Cu – 49.44
mass %.
Keywords: sintered electrical contacts, W-Cu
Cuvinte cheie: contacte electrice sinterizate, W-Cu
