Surface engineering characteristics of ultrasound assisted hypophosphite electroless plating baths

This article addresses the characteristics of metallic skin layer and the performance of hypophosphite based ultrasonic electroless plating baths during the fabrication of nickel/ceramic microfiltration membranes. The process performance was evaluated in terms of overall conversion and metal plating efficiency, and the metal film was characterised in terms of average film pore size, average effective porosity, film thickness and per cent pore densification. Parametric investigations were carried out for a wide range of initial nickel solution concentrations (0·04–0·16 mol L⁻¹) at two different loading ratios (196 and 393 cm² L⁻¹) for sonication coupled electroless plating. A simple mass transfer model was developed to provide insights with respect to the pertinent mass transfer limitations. Sonication resulted in faster deposition rate, better efficiency and improved surface morphology. In comparison with conventional and agitated electroless plating baths, ultrasound assisted electroless plating provided the best combination of process as well as performance characteristics.