Experimental fouling investigation with electroless Ni-P coatings

Advanced fouling mitigation techniques include approaches to increase the duration of the induction period and/or to decrease the fouling rate during the deposition process. One such technique is to generate heat transfer surfaces with high repulsive forces to make them less attractive to the deposition of dissolved or suspended matter. The present work investigates and compares different electroless Ni-P coatings with or without boron-nitride (BN). The incorporation of boron-nitride into Ni-P coatings increases the electron donor component of surface energy which in turn reduces the propensity of the coating to fouling. A systematic set of fouling runs has been conducted to investigate the influence of these coatings on the interaction energies between CaSO₄ deposits and modified surfaces. The results show that the Ni-P coatings with Boron-nitride exhibit excellent anti-fouling behaviour compared to pure Ni-P coatings or untreated stainless steel surfaces. Surfaces having a higher electron donor component in case of Ni-P-BN produce a higher repulsive energy which causes the adhesion force between the surface and deposits to decrease. A simultaneous set of reproducibility and cleanability experiments, however, reveals that the observed surface properties of the investigated coatings are prone to significant aging after each fouling run, leading to poor abrasion resistance.