Additive manufacturing of high-performance Ni-Co coatings for micro/nanomold applications using an advanced gradient ultrasonic electrochemical deposition process

The mass production of polymeric microdevices using microinjection molding or nanoimprinting necessitates high-performance micro/nano Ni-Co moulds. However, the achievement of a synergistic enhancement of the mechanical and lubricating properties of Ni-Co mould through general electrodeposition process remains challenging. This study for the first time proposes a gradient ultrasonic-assisted electrodeposition process to investigate its impact on the microstructural, mechanical, and tribological properties of Ni-Co coatings. Meanwhile, wear simulations are also conducted to elucidate the deterministic relationship of microstructure-process-properties by integrating surface topography and dynamically changing the coefficient of friction (COF) in the wear model. Our findings show that a high Co content (Ni: Co = 5:5) along with gradient-increased ultrasonic power (30–100 W) achieves maximum hardness (approximately 489 HV) and minimum COF (approximately 0.17), indicating a 1.73-fold hardness increase and 72% COF decrease relative to Ni coating. Such improvements result from grain refinement, reduced lattice distortion, and increased hydrophobicity, driven by the synergistic enhancement of high Co content and gradient ultrasonic power. Wear simulations highlight the undeniable impact of surface roughness and dynamic COF, which is vitally important for micro/nanomolds applications. This study realizes the integration of wear model–ultrasonic-process–microstructure–properties of Ni-Co coatings, offering valuable insights into the development of high-performance micro/nano Ni-Co moulds based on gradient ultrasonic-assisted electrodeposition process.