Strength Deterioration of Sintered TiB2 Produced by EDM and its Recovering Technology

The bending strength deterioration of sintered TiB2 (electrical conductive ceramics) produced by electrical discharge machining (EDM) and its recovering technology have been studied. The strength deterioration of EDMed ceramics occurs under the conditions of high peak current with long pulse duration. Roughness and cracks of the EDMed surface are considered to cause the deterioration. Chemical etching and electro-chemical etching onto the EDMed surface of the ceramics were carried out in order to recover the strength. The strength recovered conspicuously by removing the EDMed surface layer with several tens micrometers. Finish EDM with silicon powder suspended working fluid is expected to be effective in avoiding the strength deterioration for the reason of discharge dispersion.