Abrasive wear behaviour of laser clad and flame sprayed-melted NiCrBSi coatings

• Published in: Surface & coatings technology 2006-08, Vol.200 (24), p.6854-6862
• Main Authors: Navas, C., Colaço, R., de Damborenea, J., Vilar, R.
• Format: Article
• Language: English
• Subjects: Applied sciences; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Hardfacing alloys; Laser cladding; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metallic coatings; Metals. Metallurgy; Other topics in materials science; Physics; Plasma spraying; Production techniques; Surface treatment; Wear
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2005.10.032

In this work, the influence of the processing conditions on the microstructure and abrasive wear behaviour of a NiCrBSi hardfacing alloy is analysed. The hardfacing alloy was applied in the form of coatings onto a mild steel substrate (Fe–0.15%C) by different techniques: laser cladding (LC) and flame spraying (FS) combined with surface flame melting (SFM). In both cases, the appropriate selection of the process parameters enabled high-quality, defect-free NiCrBSi coatings to be obtained. The microstructure of the coatings was analysed by scanning electron microscopy (SEM), with attached energy dispersive spectroscopy (EDS) microprobe, and by X-ray diffraction (XRD). Their tribological properties were evaluated by micro-scale ball cratering abrasive wear tests using different abrasives: diamond, SiC and WC. Microstructural characterisation showed that both coatings exhibit similar phases in their microstructure, but the phases present differ in morphology, size distribution and relative proportions from one coating to another. Wear tests showed that in three-body abrasive conditions, despite these microstructural differences, the wear behaviour is comparable for both coatings. Conversely, in two-body wear conditions with diamond particles as the abrasive, it was observed that the specific wear rate of the material is sensitive to microstructural changes. This fact is particularly apparent in LC coatings, in which the zones of the layers with higher proportions of very small hard particles present a lower wear resistance. These results indicate that it is important to have good microstructural control of this material, in order to obtain coatings with an optimized and homogeneous tribological behaviour.