Microstructure and performance of Nb-bearing Ni60A-Cr3C2 coatings manufactured by laser cladding

摘要

The Ni60A-Cr3C2 coatings with different Nb addition were prepared by laser cladding. The microstructure was observed by SEM and TEM. The chemical composition of phases was studied by X-ray diffractometer and Electron Probe Micro-analyzer (EPMA). Microhardness and wear behaviour were measured by microhardness tester and wear tester, respectively. The results show that the main phases in Ni60A-Cr3C2 coating are gamma-Ni, Cr7C3, Cr23C6, Ni3Si2, Ni3B and CrB. With Nb addition, the NbC phase appears in the coatings. The size and volume fraction of NbC increase with the increase of Nb addition. The hardness and wear resistance increase first and then decrease with the increase of Nb addition. The micro-hardness of coatings with 2 wt-% Nb addition is the highest, reaching 1046.6 Hv0.2. The relative abrasive resistance of coatings with 3 wt-% Nb addition is the best, and is 2.33 times that of Nb-free coatings.