Properties of WC‐CoCr Based Coatings Deposited by Different HVOF Thermal Spray Processes

Abstract

The technology of high‐velocity oxygen fuel (HVOF) thermal spraying is today one of the more important processes used to apply carbide based coatings. HVOF spraying has been transforming from gas‐fuelled towards liquid‐fuelled systems. An apparent benefit from this development is to use low‐cost fuels such as kerosene. In this work a WC‐CoCr powder was thermally sprayed by three different variants of the high velocity oxy‐fuel process, in which the fuels were hydrogen and kerosene. This study was carried out in order to evaluate the influence of HVOF spray parameters on some coating properties. Investigations into the microstructural evolution of the coatings, using scanning electron microscopy and X‐ray diffraction, are presented along with results on their mechanical and tribological properties.

Microstructure and electrochemical properties of nanostructured WC–10Co–4Cr coating prepared by HVOF spraying

“…5 and 6. Similar phases have also been observed by other researchers for this kind of coating [18,19]. Fig.…”

“…4(b) it can be noted that a high volume fraction of tungsten carbide with the particle size of several micrometers are uniformly incorporated into the coating. The binder matrix with different grayscale is observed and regions with higher brightness are associated with significant dissolution of WC into the binder phase [19]. Besides, some pores and inter-lamellar oxidation are observed from the microstructure.…”

Novel Liquid Fuel HVOF Torches Fueled with Ethanol: Optimization and Erosion Wear Response of Cr3C2-NiCr Coatings

“…For higher oxygen flow rates, there is an excess of oxygen that acts as cooling gas and the shorter residence time of particles into the flame, thus causing the temperature of the particles to decrease. This will subsequently increase the porosity and reduce the hardness of the coating [15,26,27]. It was also observed in Fig.…”

HVOF-sprayed Coating Over AISI 4140 Steel for Hard Chromium Replacement

“…For HVOF coated specimens the predominant presence of the WC phase was observed 21 . For the curve between the angles of 30° and 50° in 2θ (Figure 1) a cobalt and chromium binding phase of amorphous or nanocrystalline nature is attributed 19,22,23 . This amorphous phase is often found in this type of coating because of its high cooling rate 22,24 .…”