THERMALLY SPRAYED TiC-Ni BASED COATINGS: EXPERIENCE ON SPRAYABILITY AND COATING PROPERTIES

摘要

Thermally sprayed coatings based on the system titanium carbideickel (TiC-Ni) have recently found a lot of interest because of several attractive properties, such as good wear and corrosion resistance, low weight loss, high temperature stability, good possibilities to tailor powder composition to selected applications, good sprayability by different thermal spray processes, etc. In the present work, TiC-Ni based powders manufactured by spray drying and subsequent conventional sintering were sprayed by different thermal spray processes including atmospheric plasma spraying (APS), detonation gun spraying (DGS) and high-velocity oxy-fuel spraying (HVOF). The TiC-Ni system was alloyed by one or more of the elements Mo, Co and N to improve the coating properties. The coatings were characterized and their wear resistance was evaluated.The results showed that the novel TiC-Ni based powders are sprayable by all the spray processes studied. It was found that alloying with Mo and N leads to an improvement of the coating properties. Some porosity with simultaneously developed hardmetal-like microstructure in the powder granules was found to be beneficial in order to melt the particles more efficiently in the DGS and HVOF processes. HVOF spraying of the powders with the higher binder content of 27 vol.-% was found to be advantageous to prepare coatings with dense microstructures and good wear resistances. The properties of optimized TiC-Ni based APS, DGS and HVOF sprayed coatings were found to be comparable with the conventional WC-Co and Cr_3C_2-NiCr coatings.