The present work reports an experimental investigation on Powder-Mixed Electro-Discharge Machining (PMEDM) of Inconel 718 superalloy using Multi-Walled Carbon Nanotubes (MWCNTs) dispersed in kerosene, as dielectric media. Effects of variation of peak discharge current along with concentration of carbon nanotubes in the dielectric fluid are studied in purview of machining performance indicators including material removal efficiency, tool wear rate, and surface integrity of the machined part. The obtained results are compared to that of conventional EDM which utilizes kerosene as dielectric media. Morphology and topography, these two aspects of machined surface integrity are deliberated. The following surface morphological features: uneven fusion structure, globules of debris, molten metal deposition, surface cracks, pockmarks, and recast layer are identified. Topographical study includes surface roughness, severity of surface cracking, recast layer thickness, transfer of foreign elements, surface metallurgical characteristics, residual stress, and micro-indentation hardness. It is observed that application of MWCNT mixed dielectric media substantially improves EDM performance of Inconel 718 over conventional EDM. This is due to excellent thermo-physical properties of carbon nanotubes.

本工作报告了使用分散在煤油中的多壁碳纳米管（MWCNT）作为介电介质对Inconel 718高温合金进行粉末混合电火花加工（PMEDM）的实验研究。在加工性能指标的范围内研究了峰值放电电流的变化以及介电液中碳纳米管浓度的变化，这些指标包括材料去除效率，工具磨损率和被加工零件的表面完整性。将获得的结果与使用煤油作为电介质的常规EDM进行比较。形态和地形，这两个方面的加工表面完整性进行了审议。以下表面形态特征：不均匀的熔合结构，碎屑小球，熔融金属沉积，表面裂纹，麻点，和重铸层被识别。地形学研究包括表面粗糙度，表面裂纹的严重程度，重铸层厚度，外来元素的转移，表面冶金特性，残余应力和微压痕硬度。可以看出，与传统的EDM相比，MWCNT混合介电介质的应用大大提高了Inconel 718的EDM性能。这是由于碳纳米管具有出色的热物理性质。