EDM Electrodes

Claim 1

A shaped, electrical discharge machining electrode, consisting essentially of: (1) a monolithic skeleton consisting essentially of (a) granules of carbon and (b) granules of a refractory material selected from the group consisting of tungsten, molybdenum, carbides of these two metals and stoichiometric and hyperstoichiometric carbides of the other elements of groups IVB, VB, and VIB of the Periodic Table of the Elements, the majority of said carbon granules being greater than about one micrometer in mean diameter, said refractory material being wettable by molten copper or silver, said carbon granules and said refractory granules being interconnected at their contiguous points of contact; and (2) a continuous phase consisting essentially of copper, silver, or alloys containing copper or silver, and occupying the connected porosity in said skeleton; wherein the volume percent of said carbon, said refractory, and said continuous phase are on or within the boundaries DEFG of FIG. 7, and the fraction expressed by the formula ##EQU9## wherein C is said carbon, R is said refractory, the volume percent terms are the fraction of said electrode occupied by C or R, and the surface area terms are the surface areas in m 2 /g of said carbon or refractory granules measured before said carbon or refractory granules are used in making said electrode, is less than about 75, said electrode thereby being a monolithic structure consisting essentially of two intermeshed matrices, being substantially free of voids, and being substantially free of materials which are soluble in said continuous phase and reactive with carbon.