Addition of molybdenum disulfide solid lubricant to WC-12Ni thermal spray cemented carbide powders through electroless Ni-MoS2 co-deposition

Abstract

Molybdenum disulfide solid lubricant was added to thermal spray WC-12Ni powders through electroless Ni-MoS2 co-deposition. With varying the concentration of WC-12Ni and MoS2 particles in the plating bath, varied concentration of MoS2 can be controlled in the powder surface layer and the incorporation mechanism of MoS2 into the shell was discussed as well. The thickness of the Ni-MoS2 coatings as well as the MoS2 distribution structure were characterized with a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS). The phase structure of the co-deposited coatings was characterized with X-ray diffraction (XRD). It is found that MoS2 particles can be co-deposited with Ni to form a Ni-MoS2 composite layer on WC-12Ni powders when effective Ni electroless deposition occurs, since Ni or Ni2+ can encapsulate MoS2 particles to facilitate its incorporation. The content of MoS2 in the coating increases with increasing the concentration of MoS2 in the plating bath, or with decreasing the concentration of WC-12Ni powders in the bath which results in increased thickness of deposited Ni- MoS2 layers. The Ni-MoS2 coated WC-12Ni powders obtained with the electroless co-deposition process can be used for high velocity oxy-fuel spraying (HVOF) with a proper size and adequate fluidity, and are expected to suppress desulfurization and decarburization effectively.