Tribological properties of Ni-P-Al2O3 coatings

The paper is aimed on experimental investigations leading to determinations of appropriate conditions for manufacturing composite chemical coatings Ni-P-Al2O3 by the currentless method without or with thermal treatments. The optimal process parameters for Ni-P-Al2O3 deposits on the surface of the steel St3 have been determined. The coatings Ni-P and Ni-P-Al2O3 have been subjected to thermal treatments at the temperature equal to 673 K. Investigations of the structure, hardness and the abrasion wear of the composite coatings before and after thermal treatments have been performed. Influences of the particle dimensions of the dispersed phase Al2O3 on the tribological properties of the resulting composite coatings have been examined. Comparison analysis of the properties of the Ni-P and Ni-P-Al2O3 deposits exhibited that the dispersive phase of the aluminium oxide and the post-manufacturing thermal treatment improve importantly the resistance of the coatings on their mechanical destruction. (author)