Abstract: NiCrWB cladding layer was prepared by high energy density laser-remelting of NiCrWB spraying layer from high velocity air fuel spray (HVAFS). The phase compositions, structures and patterns of the two layers were investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM) and optical microscopy (OM). The worn surface morphologies of the two layers were examined by SEM and OM, and the sliding wear mechanism of the cladding layer and the spraying layer were suggested. In addition, the effects of the phase structure and pattern of the layers on the wear-resistance were investigated. The result showed that the structure was the main factor affecting the wear-resistance of the layers. The cladding layer had a lower microhardness than that of the spraying layer, while the wear-resistance of the cladding layer was better than that of the spaying layer because of the dense and uniform structure and few of defects. Many fatigue cracks, ruts, abrasive particles and deep grinding cracks were found on the worn surfaces of the spraying layer It is deduced that cracks originated from surface layer and subsurface layer coalesced under the cyclic load and resulted in detachment of wear particles. However, the cracks in the cladding layer were generated by the plastic deformation of the abrasive surfaces.

Key words: laser cladding; NiCrWB alloy; HVOFS; sliding wear

Corresponding author: CHEN Zhi-kun, Guangzhou Research Institute of Non-ferrous Metals, Guangazhou 510650, China

E-mail: chenzhikun001@yahoo.com.cn

Tribology, Vol. 30, Issue 4, 2010, 344~349