Investigation of machining and modified surface features of 316L steel through novel hybrid of HA/CNT added-EDM process

Hydroxyapatite powder (HAp) mixed-EDM process causes surface defects including a high roughness, crack and a thick recast layer attributing a low wettability and amorphous alloys as well as a low material erosion rate (MER) while processing the metallic biomaterials. To mitigate these occurrences, many measures have been conducted. This research aims to investigate the feasibility of hybrid HA and carbon nanotubes (CNT) powders mixed EDM process for processing 316L steel. This study also aims to explore the impacts of CNT and the associated variables on machining and surface characteristics of 316L steel. To ameliorate the machining and surface responses, a high electrically and thermally conductive CNT particles have been added in the HAp suspended mineral oil. To address the set objectives, several characterizations techniques including profilometer, goniometer, energy dispersive X-ray (EDX), X-ray diffraction (XRD), and scanning-electron microscope (SEM) have been carried out. In this study, the multiple additives (HAp and CNT) mixed-EDM process has been successfully introduced. Addition of the CNT in the HAp mixed mineral oil improves MER to 26.47 mg/min and declines SR to 3.16 pm. A thin uniform recast layer of 12.4 pm attributing cracks free surface and a high hydrophilic in nature having contact angle of 35 degrees has been obtained in this study. Elemental composition analysis reveals a high content of Ca, P, O and C in the recast layer formed. The oxides, carbides, and CNT reinforced Ca-P based oxides with both crystalline and amorphous phases have been achieved. In this research work, a novel and effective method for processing the biomedical devices made of 316L steel has been proposed.

Automated summary

The study successfully introduced a mixed-EDM process with multiple additives (HAp and CNT), achieving improved material erosion rate (MER) and surface roughness (SR). The addition of CNT in the mineral oil resulted in a thin, uniform recast layer with high hydrophilicity and elemental composition analysis revealed a combination of oxides, carbides, and CNT reinforced Ca-P based oxides. This research presents a novel and effective method for processing biomedical devices made of 316L steel.