Effect of nano-CeO2 on microstructure and wear resistance of Co-based coatings

Co-based composite coatings with different nano-CeO2 contents were successfully prepared on SPHC steel by laser cladding. The effect of nano-CeO2 on microstructure and properties of Co-based coatings were systematically investigated. The phase construction and microstructure of the coatings were characterized by optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray spectrometer (EDS). The hardness and wear resistance of the coatings were evaluated by HV-1000 hardness tester and MM-200 type wear tester at room temperature as well as applied multivariate statistical analysis method. The results indicated that Co-based coatings with nano-CeO2 exhibited an excellent appearance quality, another fine microstructure and new phase Ce2Ni7 appeared. The microhardness and wear resistance of coatings first improved and then decreased with increasing nano-CeO2 content in the coatings and the improvement in microhardness and the reduction in total loss were respectively 35.3% and 55.0%, at 1.5 wt% nano-CeO2, the wear mechanism was abrasive wear. The great effect of nano-CeO2 addition on microhardness and wear resistance of coatings were consistent with the calculation results of applied multivariate statistical analysis. Thus, it is concluded that adding nano-CeO2 is an effective and attainable way to improve the wear resistance of Co-based coatings. (C) 2015 Elsevier B.V. All rights reserved.