Characterization and potential use of ionic liquid-blended vegetable oils as dielectric fluids in electrical discharge machining of Inconel 718 using copper electrode
MATERIA-RIO DE JANEIRO, vol.30, 2025 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 30
- Publication Date: 2025
- Doi Number: 10.1590/1517-7076-rmat-2025-0675
- Journal Name: MATERIA-RIO DE JANEIRO
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Directory of Open Access Journals
- Istanbul University Affiliated: No
Abstract
This study investigated the effect of environmentally sustainable dielectric fluids composed of a 5 wt.% ionic liquid (IL) blend of vegetable oils (sunflower, coconut, corn and neem) on the performance of electrical discharge machining (EDM) of Inconel 718. A copper square electrode was used with controlled variations in gap voltage, discharge current, pulse interval and pulse duration. Key performance metrics such as material removal rate (MRR), recast layer thickness (RLT) and residual stress (RS) were evaluated. Among the combinations tested, corn oil mixed with ionic liquid delivered the highest MRR. Dielectrics with higher constants enhanced spark penetration, but produced thicker recast layers; conversely, those with lower constants yielded smoother surfaces and reduced recast layer thickness. RS levels were also found to be linked to dielectric properties: higher constants generated stronger sparks and elevated stress, whereas oils such as neem, which have lower constants, provided a better thermal balance and minimized stress. X-ray diffraction (XRD) analysis showed the presence of gamma-Ni, Cu-Ni, Ni3Nb and Ni3C phases consistently across all conditions. Coconut and corn oils encouraged carbide formation, whereas ionic liquid blends resulted in nitrides, fluorides, and phosphides due to their reactive constituents.