Effect of Nb and CeO2 on the mechanical and tribology properties of Co-based cladding coatings

• Co50 plasma cladding coatings were modified by a small addition of Nb and CeO2.
• Addition of Nb and CeO2 makes the microstructure much finer.
• The properties of tensile and wear are improved with the addition of Nb and CeO2.

Nb and CeO2 modified Co-based coatings were produced on 45 steel by plasma cladding. The effect of Nb and CeO2 on microstructure, tensile property and high temperature abrasive wear resistance was investigated. Results indicate that γ-Co, Cr23C6 exists in all coatings, and NbC forms in the Nb-contained and Nb/CeO2-contained cladding coatings. Co-based coating has a fine columnar crystal and dendritic microstructure, finer grain size and equiaxed dendrites are obtained by adding Nb/CeO2. The introduction of Nb and CeO2 reinforcements shows a positive effect on the tensile property due to purification and grain refinement. Tensile fracture mechanism of the composites is primarily controlled by particle cracking as a result of effective load transfer from matrix to the reinforcements. A relatively high temperature wear resistance occurs with Nb and CeO2 modification due to the distribution of high hardness carbide NbC in the clad coating as well as the dense and uniform microstructure.