CLADDED COMPOSITE TiCrC(Ni) POWDERS FOR THERMAL SPRAYING OF COATINGS

Abstract

The carbonyl cladding method was employed to produce composite metal-ceramic TiCrC(Ni) powders from double titanium–chromium carbide with 17, 25, and 33 wt.% Ni. To deposit coatings by plasma, detonation, and high-speed gas-flame spraying, powder materials of different size fractions, μm, were produced: −80+40, −63+40, and −40+20, respectively. The composite TiCrC(Ni) powder particles are were of irregular shape and consisted of a refractory core with 18–26 GPa microhardness, surrounded by a ductile nickel layer. Electron microprobe analysis revealed that the ceramic core included two phases: main TiCrC phase and interspersed Cr₇C₃ phase. The nickel layer deposited on titanium–chromium carbide particles became thicker with higher nickel content of the composite TiCrC(Ni) powders and varied from 0.5 to 4 µm. The effect of nickel content on the process properties (bulk density and flowability) of the developed powders was determined. The bulk density of the TiCrC(Ni) powders was not found to substantially depend on their particle size distribution or nickel content and was 2.3–2.6 g/cm³ on average. The flowability of the TiCrC(Ni) powders was found to depend on their particle size composition and nickel content. The flowability of the TiCrC(Ni) powders improved with increasing particle size and was 41.2–51.4 sec for the −63+40 µm powders and 40.2–47.0 sec for the −80+40 µm powders. The −40+20 µm TiCrC(Ni) powders for gas-flame spraying had very poor flowability and thus could be used only for coating deposition units with forced supply of powder to the spraying area. Their flowability became higher with nickel content of the composite TiCrC(Ni) powders increasing from 17 to 33.5 wt.%.