HVOF sprayed high chromium and high vanadium containing iron based hard coatings for combined abrasive wear and corrosion protection

HVOF sprayed WC/Co(Cr) and Cr₃C₂/Ni20Cr composite coatings have gained high acceptance in many industrial applications for protection of components against wear. The achieved coatings have quite good corrosion resistance for use of chromium containing matrices. Present research in the field of PTA-Surfacing resulted in the development of high chromium and high vanadium containing iron based hard alloys with simultaneous improvement of abrasive wear and corrosion resistance.

These properties of the PTA-Surfaced coatings were studied and it was found that the newly developed alloys have nearly same wear resistance and improved corrosion resistance compared to Co-based alloys reinforced with Fused Tungsten Carbides (FTC). One major advantage of high chromium and high vanadium containing iron based coatings is machinability by turning and milling processes. These features make it attractive to be used in thermal spraying. The absence of substrate melting in HVOF-spraying is advantageous, as the coatings preserve the properties of the alloy due to prevention of dilution with substrate material in contrast to PTA-Surfacing. High chromium and high vanadium containing iron based atomized powder was used for HVOF spraying and deposition efficiency was measured. The sprayed coatings were studied metallographically by optical microscopy, SEM, XRD and micro-hardness measurements. Later, abrasive wear and corrosion properties of the coatings are investigated.

Wielage, B., A. Wank, H. Pokmurska, U. Dilthey, B. Balashov, J. Gollnick, L. Stein, S. Kondapalli, E. Deppe, T. Schnick

Proceedings of the International Thermal Spray Conference, Basel, Switzerland, May 2nd - 4th 2005, pp. 887-891, ISBN 3-87155-793-5