Elaboration and characterization of (Cu-W) electrodes for EDM machining of carbide materials

Abstract

The object of research is the system of electrode blanks used for electrical discharge machining (EDM) of P35 hard alloy components, in particular a pseudo-alloy electrode based on W-Cu, modified with Ni or Co and reinforced with TiC. The development of modified W-Cu electrodes made it possible to minimize the tool wear rate (TWR) and improve the surface quality of P35 hard alloy components during EDM. To increase the efficiency of W-Cu-based electrodes, the powders were cold pressed at 0.2 MPa at room temperature and sintered-infiltrated at 1200°C in a reducing hydrogen (H2) atmosphere. Copper and nickel acted as metallic catalytic sealants in combination with a dispersed ceramic phase of titanium carbide (TiC). The results show that the modified cobalt-titanium carbide (Co-TiC) composite achieved the highest Vickers microhardness of 326 HV while exhibiting optimal erosion protection. Machining of P35 carbide using a W-Cu-Co-TiC electrode composite resulted in 50% less volumetric wear than using an equivalent nickel electrode composite W-Cu-Ni-TiC. The strong chemical affinity between the cobalt carbide matrix, tungsten, and titanium carbide promotes the development of an elastic microstructural network. The dispersed TiC inclusions attenuate the propagation of thermal shocks, effectively suppressing localized microstructural delamination and grain separation during high-temperature plasma spark interactions. Synergistic activation of Co and strengthening of TiC directly improve the tribological wear resistance and operational reliability of W-Cu electrodes in contact with refractory carbide substrates.