Enhancing heat-affected zone/hardness and decreasing crack length of Inconel 718 using coconut oil-based dielectric modified with CuO, TiO<sub>2</sub>, and SiC nanoparticles and optimized process parameters
MATERIA-RIO DE JANEIRO, vol.31, 2026 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 31
- Publication Date: 2026
- Doi Number: 10.1590/1517-7076-rmat-2026-0088
- Journal Name: MATERIA-RIO DE JANEIRO
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Directory of Open Access Journals
- Open Archive Collection: AVESIS Open Access Collection
- Istanbul University Affiliated: No
Abstract
In order to enhance the thermal conductivity of the dielectric medium, CuO, TiO2, and SiC nanoparticles were blended with coconut oil (CO) for electrical discharge machining (EDM) of Inconel 718 using copper electrodes. Four dielectric variants were prepared: pure coconut oil, CO mixed with copper oxide (CO + CuO), titanium dioxide (CO + TiO2), and silicon carbide (CO + SiC) nanoparticles. Key input parameters included discharge current, pulse duration, gap voltage, and stirrer speed. The experiments focused on producing blind holes while evaluating three critical quality characteristics: minimization of the heat-affected zone (HAZ), reduction in crack length (CL), and improvement in surface hardness (H). The experimental results indicated that the HAZ improved by approximately 4.9 times, while the CL and H exhibited improvements by factors of 2.5 and 1.3 times, respectively, compared to machining with pure CO. Furthermore, surface examination confirmed the formation of new phases, including NiO, Cr2O3, Ni3C, and Cr2O, which contributed to enhanced surface integrity and mechanical performance of the Inconel 718.