G. Matthäus, Thermico GmbH & Co KG, Castrop-Rauxel, Germany; K. Bobzin, E. Lugscheider, Surface Engineering Institute (IOT), RWTH Aachen University, Aachen, Germany; J. Zwick, Surface Engineering Institute, RWTH Aachen University, Aachen, Germany
HVOF spraying of carbides is a well established method to produce high performance wear and corrosion protection coatings for various industrial applications. Using ultrafine feedstock powders with particle sizes well below 25 µm can offer many advantages with respect to the resulting coating properties, such as improved coating density and homogeneity and high dimensional accuracy. In this study fine powder grades of WC 10Co 4Cr, WC 17Co, Cr3C2 25(Ni 20Cr) and Cr3C2 25(Ni 50Cr) in a particle size range of
–15+5 µm, -10+3 µm and –5 µm have been sprayed with suitable HVOF systems on outer surfaces as well as on internal diameters. Resulting coatings have been analysed with respect to coating structure and microhardness. The coatings featured a favourable microstructure and very good hardness values. Furthermore the Cr3C2 25(Ni 20Cr) material was applied as wear protection coating on piston rings. The coating performance was evaluated in engine tests and proved to be significantly better than a conventionally graded standard material system for this application.
Summary: Fine powder grades of WC 10Co 4Cr, WC 17Co, Cr3C2 25(Ni 20Cr) and Cr3C2 25(Ni 50Cr) in a particle size range of –15+5 µm, -10+3 µm and –5 µm have been sprayed with suitable HVOF systems. Resulting coatings have been analysed with respect to coating structure and microhardness.
