Accretion of titanium carbide by electrical discharge machining with powder suspended in working fluid

A surface modification method by electrical discharge machining (EDM) with a green compact electrode has been studied to make thick TIC or WC layer. T itanium ahoy powder or tungsten powder is supplied from the green compact e lectrode and adheres on a workpiece by the beat caused by discharge. To avo id the production process of the green compact electrode, a surface modific ation method by EDM with powder suspended in working fluid is proposed in t his paper. After considering flow of working fluid in EDM process, the use of a thin electrode and a rotating disk electrode are expected to keep powd er concentration high in the gap between a workpiece and an Electrode and t o accrete powder material on the workpiece. The accretion machining is trie d under various electrical conditions. Titanium powder is suspended in work ing oil hire kerosene. TiC layer grows a thickness of 150 mum with a hardne ss of 1600 HII on carbon steel with an electrode of 1 mm in diameter. When a disk placed near a plate rotates in viscous fluid, the disk drags the flu id into the gap between the disk and the plate. Therefore, the powder conce ntration in the gap between a workpiece and a rotational disk electrode can be kept high. A wider area of the accretion can be obtained by using the r otational electrode with a gear shape. (C) 2001 Elsevier Science inc. All r ights reserved.