Surface integrity of tribo-adaptive layer prepared on Ti6Al4V through μEDC process

Abstract

The work presents the surface integrity of TiN/TiAlN coated surfaces produced using hexagonal boron nitride suspension in the dielectric fluid through the micro-electrical discharge coating (μ-EDC) process. The performance of the coated surfaces is evaluated on the grounds of surface topography, wettability, indentation depth, layer height, crack density, roughness profiles, residual stress, and composition analysis. The recast layer height varies between 1.53 μm and 13.38 μm, while the water contact angle lies in the range of 91.28° to 118.23° (hydrophobicity is induced). The residual stress generated due to the presence of micro-cracks on the coated surfaces prepared at a maximum voltage (60 V) and powder concentration (12 g/L) varies between 225.87 MPa and 300.93 MPa. The occurrence of Ti, Al, Cu, Zn, V, B, N, and O in EDX plots affirmed the transfer of tool and dielectric material to the work surface. The indentation depths obtained in the study lies within the range of coating thickness. The surface roughness parameters, i.e., Ra, Rq, Rz, Rsk, and Rku are also evaluated in this work. Such micro-deposited surfaces find application in lab-on-chip devices where selective surface modification is needed.