Continuous and ordered surface microtexturing on Cu and Ni-based alloys by novel electrochemical dissolution

Abstract

The present study discusses the formation of surface micro-texture on flat samples of Cu-based and Ni-based alloys by two-step electrochemical dissolution. Prior to the electrochemical dissolution, laser marking only on the araldite coating has been carried out for effective dissolution of the selectively exposed metal surfaces along the laser cut regions. After second stage dissolution, the circular truncated conical grids with average base diameter of 210.7 μm for the Cu-based alloy and truncated square pyramid like grids with base width of 203.2 μm for the Ni-based alloy have formed. Similarly, maximum dissolution depths of 61.8 and 39.3 μm for the Cu-based and Ni-based alloys, respectively, could be observed. Moreover, excellent hydrophobicity of the textured Cu-based as well as Ni-based alloys correlating to grid dimensions along with air entrapment beneath the water droplet has been analysed with the help of Wenzel and Cassie-Baxter models. Nano-hardness of the as-received alloys as well as the textured alloy surfaces shows minor variation. Similarly, the micrographs of the flat surfaces of the as-received alloys and cross-sectional microstructure of the textured alloys have also portrayed little difference suggesting negligible heat or stress affected zone after dissolution process. Moreover, the textured surfaces have showed significant increment in surface area: ∼62.7% for the Cu-based alloy and ∼71.4% for the Ni-based alloy as compared to the flat specimens.