An investigation of the mechanical properties and wear resistance of NiCrBSi coatings carried out by in situ laser remelting

Electrolytic hard chromium has proved to be effective against wear. However, its use is about to decrease due to the toxic and carcinogenic characteristics of hexavalent chromium. A lot of promising alternatives have been already studied. Among them, thermal spraying presents a good potential. In this study, laser remelting was combined simultaneously to thermal spraying in order to modify a metal alloy coating characteristics. The mechanical properties of a nickel-base layer were investigated by nanoindentation, scratch tests, interfacial indentation and tribological ball-on-disc experiments. The influence of the coating structures on the wear behaviour of in situ remelted NiCrBSi coatings was investigated. This paper demonstrates that the remelted samples have better mechanical performances than as-sprayed coatings. Moreover, the adhesion of remelted samples was strongly increased, as well as the fracture toughness. According to the selected processing parameters, the increase of the laser energy density seems to show better mechanical results.

Research highlights
► Finding alternatives for EHC is a significant task for human's health and environment protection.
► Different thickness NiCrBSi coatings were produced by controlling hybrid process parameters.
► The main interest of the paper is in the wear testing of the coatings.
► An original method has been used to determine adhesion and cohesion by using scratch tests.