Microstructure and Wear Resistance of Ni-based Alloy Composite Coatings Prepared by Laser Melting Deposition

Abstract:

The Nb and WC composite-strengthened Grade 4 Ni-based superalloy coatings were prepared on 304NG stainless steel substrate by laser melting deposition technology. The effects of Nb and WC mass fraction on the microstructure, microhardness and wear resistance of the Ni-based superalloy coatings were studied. The results show that the coating is well combined with the substrate without obvious cracks, pores and other defects. The addition of alloying element Nb leads to new hard phases NbC and Nb₆C₅, which make the eutectic structure of the alloy denser and also improves the hardness and wear resistance of the coating. The coating with 10wt% Nb+15wt% WC shows the best wear resistance. The continuous eutectic structure changes from long strip and reticulation to four shapes of separated short strip, block, granular and fishbone. At the same time, the addition of WC transforms the wear mechanism of the coating from abrasive wear and adhesive wear to fatigue wear.