Abstract: An elongated substrate made of an electric insulating material carries an elongated conductive track made of aluminium which has a constriction in its centre part in order to increase the heating of the said centre part with a view to reducing as much as possible the volume of material to melt. The ends of the track each comprise an annular part which partially covers a nickel or aluminium pad. The connection and cooling of the ends is carried out by connection brackets. This fuse is calculated in such a way that for a rated current IN, a maximum temperature variation .DELTA.T and a length of the electric conductor designated 2b, thermal equilibrium is obtained when the relationship between the cross section S of the said conductor and that S' of the base material corresponds approximately to:S=.rho.'.sub.th..rho..sub.e.b.sup.2.IN.sup.2 /2S'..DELTA.Tmaxwhere .rho.'.sub.th is the thermal resistivity of the substrate and .rho..sub.e the electrical resistivity of the conductive track.

Abstract: A metal chalcogenide coating, in particular of molybdenum sulphide, is deposited on a substrate by high speed cathode sputtering. This coating is turbostratic and has an unusually high resistance to wear produced by frictional forces.