Super-hydrophobic and Super-hydrophilic Effect by Means of EDM Surface Structuring of γ-TiAl

Abstract Super-hydrophobic and super-hydrophilic surfaces can be produced in order to change material-environment interactions, which is useful for aerospace, automotive and medical applications. Super-hydrophobic effects can be generated by surface micro-structuring and enhanced by surface modification, which can be performed separately. Commonly, the super-hydrophilic surface is made by the coating process; however, in its current state, this technology is not capable of producing a durable effect. The material properties such as hydrophobicity and hydrophilicity depend on chemical and topographical properties of its surface and EDM enables an ability of simultaneous exploration of surface chemical modification and surface structuring. In this paper, micro-structuring of surfaces is performed by both wire electrical discharge machining (WEDM) and die-sinking EDM, so that the outcomes of these processes can be analyzed and compared. These processes are widely used for micro-manufacturing and can be applied as an industrial solution for super-hydrophobic and super-hydrophilic surfaces generation. Commonly used dielectrics, such as hydrocarbon oil and deionized water, are applied as dielectric media in order to test the ability of oxide and carbide layers creation on machined surfaces. y — TiAl is used as workpiece material since it is widely used in the aerospace industry, where enhancing of material properties is notably requested. The reported results show the feasibility of generating super-hydrophobic and super-hydrophilic effects on the same material, depending on the used dielectric medium for the EDM process. Material structuring in deionized water leads to the generation of surfaces with super-hydrophilic effects, while in hydrocarbon oil hydrophobic effects are introduced. In addition, the results show that further surface structuring is able to enhance such effects.