Mechanical and wear characterization of electroless nickel-boron coatings. Véronique Vitry 1 , Abdoul-Fatah Kanta 2 , Fabienne Delaunois 1 1 Service de Métallurgie, Faculté Polytechnique de l’Université de Mons, place du Parc n° 20, Mons, Belgique 2 Service de Science des Matériaux, Faculté Polytechnique de l’Université de Mons, place du Parc n° 20, Mons, Belgique Abstract: Nanocrystalline electroless nickel-boron deposits were synthesized on mild steel (St-37) substrates and submitted to heat treatment under non-reactive atmosphere to enhance their properties. Their mechanical and tribological properties were investigated by various methods including nanoindentation, Taber wear testing and scratch tests. Their structural properties were also studied. The hardness of the deposits increased from 900 to 1250 hv100 due to optimal crystallization of the nanocrystalline coating while the Taber wear index was halved after heat treatment. The scratch tests resistance of the coatings was good in both as-deposited and heat treated conditions. The mechanisms inducing the modification of the mechanical and tribological properties were discussed and they were linked to the structural state of the material.