Spark machining electrode

Claim 1

A SPARK MACHINING ELECTRODE FORMED OF COMPOSITE MATERIAL CONSISTING ESSENTIALLY OF A MAIN SUBSTANCE OF THE GROUP CONSISTING OF COPPER AND OF CONDUCTING AND EASILY MACHINABLE COPPER ALLOYS AND A NON-METALLIC ADDITIONAL SUBSTANCE OF THE GROUP CONSISTING OF TITANIUM HYDRIDE, ZIRCONIUM HYDRIDE, THORIUM HYDRIDE, CERIUM HYDRIDE, LANTHANUM HYDRIDE, BORON, TITANIUM BORIDE, ZIRCONIUM BORIDE, THORIUM BORIDE, CERIUM BORIDE, MOLYBDENUM BORIDE, TITANIUM CARBIDE, ZIRCONIUM CARBIDE, THORIUM CARBIDE, CERIUM CARBIDE, MOLYBDENUM CARBIDE, VANADIUM CARBIDE, TANTALUM CARBIDE, SILICON CARBIDE, CHROMIUM CARBIDE, TUNGSTEN CARBIDE, BORON CARBIDE, TITANIUM NITRIDE, ZIRCONIUM NITRIDE, THORIUM NITRIDE, BORON NITRIDE, SILICON NITRIDE, ZIRCONIA, COPPER OXIDE, SILICON, TITANIUM SILICIDE, ZIRCONIUM SILICIDE, THORIUM SILICIDE, CERIUM SILICIDE, MOLYBDENUM SILICIDE, TITANIUM SULPHIDE, ZIRCONIUM SULPHIDE, THORIUM SULPHIDE, CERIUM SULPHIDE, MOLYBDENUM BISULPHIDE, SILICON SULPHIDE, SILVER SULPHIDE, CADMIUM SULPHIDE AND ZINC SULPHIDE, SAID ADDITIONAL SUBSTANCE BEING INCORPORATED IN SAID MAIN SUBSTANCE IN THE FORM OF A FINE DISPERSION THEREIN, THE AMOUNT OF SAID ADDITIONAL SUBSTANCE BEING COMPRISED BETWEEN 0.1 AND 10 PERCENT BY WEIGHT OF THE TOTAL MIXTURE AND ITS AVERAGE GRAIN SIZE BEING LOWER THAN 150 MICRONS.