Effect of Plasma Cladding Speed on the Microstructure and Properties of ZrC-ZrB₂/NiAl Coating

NiAl composite coating strengthened by ZrC and ZrB₂ phases is synthesized by the plasma cladding process. The influence of cladding speed on microstructrue and properties of coatings is studied. The main phases of coatings are NiAl, γ-(Fe,Ni), ZrC and ZrB₂ phases. ZrC is in the shape of points and small blocks, ZrB₂ shows long strips and needle bar. The slower the cladding speed, the larger the size of the reinforcing phases. With the increase of cladding speed, the wear resistance of the coatings improves. Coating with the cladding speed of 10mm/s has excellent wear-resistance property owing to high hardness and low friction coefficient. ZrC and ZrB₂ strengthening phases play an important role. The main wear mechanism of NiAl composite coating is adhesive wear.

Keywords:
ZrC-ZrB₂/NiAl composite coating; in-situ synthesis; wear resistance; microhardness