Microstructure and Wear Resistance of Laser Cladding Nano-CeO_2/Co-based Alloy Composite Coating

TL;DR: In this paper, the effects of nano-CeO_2 particles on the macroscopic quality, microstructure, phase structure, and properties of Co-based cladding layer were investigated.

Abstract: The effects of nano-CeO_2 particles on the macroscopic quality,microstructure,phase structure,and properties of Co-based cladding layer were investigated.The coatings were prepared by a 5 kW CO_2 laser,the microstructure and phase structure of the cladding layers were analyzed by means of OlympusPme 3 type microscope,Philip Xl 30 type scanning electron microscope and XD-3A type X-ray diffractometer(XRD).The wear resistance was measured with MM-200 type sliding wear tester,and the wear mechanism was analyzed by JSM-35C type scanning electron microscope(SEM) respectively.The results indicated that the addition of nano-CeO_2 can improve the macroscopic quality of the cladding layers and smooth coatings without defects(such as crack,gas hole,etc.)are obtained;the nano-CeO_2 addition can not only refine microstructure,but also restrain the dendritic growth and promote the formation of equiaxed grains;the addition of nano-CeO_2 can result in the formation of new phase CeCo_2,and transform some γ-Co phase into e-Co phase as well.The cladding with 1.5% CeO_2 addition made at 2.0 kW laser power has the best relative wear resistance.The mechanism was found to transform from abrasive/adhesive wear to fretting wear.However,the wear resistance decreased with excess CeO_2 addition.