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The EDM process improved the SBS. In addition, there was no significant adverse effect of EDM on the flexural strength of zirconia.

The main aim of this study is to produce new powder metallurgy (PM) Cu-B 4 C composite electrode (PM/(Cu-B 4 C)) capable of alloying the recast workpiece surface layer during electric discharge machining process with boron and other hard intermetallic phases, which eventually yield high hardness and abrasive wear resistance. The surface characteristics of the workpiece machined with a PM/(Cu-B 4 C) electrode consisted of 20 wt% B 4 C powders were compared with those of solid electrolytic copper (E/Cu) and powder metallurgy pure copper (PM/Cu) electrodes. The workpiece surface hardness, surface abrasive wear resistance, depth of the alloyed surface layer and composition of alloyed layers were used as key parameters in the comparison. The workpiece materials, which were machined with PM/(Cu-B 4 C) electrodes, exhibited significantly higher hardness and abrasive wear resistance than those of machined with the E/Cu and PM/Cu. The main reason was the presence of hard intermetallic phases, such as FeB, B 4 C (formed due to the boron in the electrode) and Fe 3 C in the surface layer. The improvement of the surface hardness achieved for steel workpiece when using PM/(Cu-B 4 C) electrodes was significantly higher than that reported in the literature. Moreover, the machining performance outputs (workpiece material removal rate, electrode wear rate and workpiece average surface roughness (R a )) of the electrodes were also considered in this study.