Instantaneous deposition of functional coating with adjustable wettability via multi-phase thermal plasma jet

Electrical explosion of metal wire comes with high-density thermal plasmas that can generate multiscale micro-nano surface structures benefiting functional performance in many scenarios. In this paper, supersonic plasma jet has been achieved via electrical explosion of a Cu wire, enabling ‘single-step’ fabrication of high-quality super-hydrophilic coatings (⩽6° contact angle). Then, we optimize the plasma premixing chamber by adding non-metal particles (40-260 μm), resulting in a multiphase jet comprising continuous-phase plasma and dispersed-phase solid particles. The deposited composite coating with distinct structural and compositional heterogeneity exhibits evidently hydrophobic properties (152.3°^±3.3 contact angle). To find out more physical details, high-speed photography is adopted to reveal jet dynamics (speed 0.6 km s⁻¹ at kJ-level discharge energy) and coating deposition process (5 ms). Supersonic plasma jet brings small particles (e.g., diamond) that impact the sample surface, forming robust mechanical interlocking. Simultaneously, metal plasma undergoes attachment, nucleation, and stacking-melting processes, establishing consolidated metallurgical bonding structures. Microscopic characterization further confirms composite coatings with micron-scale non-metallic particles and micro-nano metallic particulates. By modulating premixed particle sizes and plasma discharge parameters, tunable wettability across a broad range (95°-152°) is achieved, resulting in hydrophobic coatings. This study demonstrates the tunability of ‘one-step method’ prepared hydrophilic/hydrophobic metal coatings. By adjusting the ratio of non-metallic particles to metal wires, coatings with varying hydrophilicity/hydrophobicity can be obtained. This approach enhances coating preparation efficiency while further expanding the applicability range of the design.