Abstract: A mechanically assisted electroless (MAE) barrel-plating technique has been developed to deposit Ni-P coatings on carbon steel. The mechanical treatment was carried out in a rolling drum containing carbon steel specimens and glass balls of 2−3 mm diameter, which was submerged in a bath containing electroless plating solution. The coatings are Ni-polycrystalline and have a fine grained structure and smooth surfaces. The hardness and corrosion resistance of the novel coatings are considerably improved compared with the conventional electroless (CE)-plated Ni-P coatings, which are amorphous. After heat treatment at 400°C for one hour, cracks and pores are observed in the CE-plated Ni-P coating, while no cracks appear in the MAE barrel-plated Ni-P coating. The improved properties of the MAE barrel-plated Ni-P coatings demonstrate the advantages of this novel technique, wide applications of which will be found in industries.

Key words: Mechanically assisted electroless barrel-plating, Ni-P coating, Crystallization, Corrosion resistance, Microhardness