Experimental investigation on electric discharge-assisted surface modification of Ti6Al4V with comparative analysis between different polarities in ecofriendly dielectric deionised water

Electric discharge machining (EDM) is the most widely used non-conventional machining process for machining difficult-to-cut materials in complex geometries and intricate cavities with less cost. The main problem associated with EDMed part is its increased surface roughness (SR). This article made an attempt on surface modification of Ti6Al4V by reducing SR with different polarities of EDM in deionised water, an eco-friendly dielectric. Experiments were performed on both straight and reverse polarities in full factorial with varying two factors (voltage and current) in two levels. The substrate processed with the reverse polarity possesses minimum (1.26 mu m) SR of about 2.15 times than that of the straight polarity (2.64 mu m) at the parametric conditions of 60 V, 10 A and 100 mu s. Enhanced microhardness (300-450 HV1) and specific wear rate (2.4 x 10-4 mm3/Nm) were observed with the straight polarity due to the microstructural changes along with higher SR and defects. Contact angle analysis reveals that both straight and reverse polarity processed parts are hydrophilic in nature. Reverse polarity can be used as an effective tool for surface modification with less SR and defects and with slight increase in microhardness (300-400 HV1) and specific wear rate (2.6 x 10-4 mm3/Nm). The presence of enriched titanium oxide (rutile) observed on the reverse polarity surface increases its applicability, especially in biomedical industries.