Laser cladding of Co-based alloy/TiC/CaF2 self-lubricating composite coatings on copper for continuous casting mold

In this study, Co-based alloy/TiC/CaF2 self-lubricating composite coatings were successfully prepared on a Cr-Zr-Cu alloy for continuous casting mold by Nd:YAG laser cladding. The microstructure, phase structure and wear properties were investigated by means of scanning electron microscopy (SEM) incorporating energy dispersive X-ray (EDX) and X-ray diffraction (XRD), as well as dry sliding wear test against GCr15 steel at a temperature of 400 degrees C. The results showed that the Co-based alloy/FiC/CaF2 self-lubricating composite coatings had a unique microstructure consisting of well-developed small fine spherical TiC and CaF2 particles uniformly dispersed in the gamma-Co matrix. Average hardness of the Co-based alloy/20% TiC/10% CaF2 (vol.) self-lubricating composite coating was about twice times that of the pure Co-based alloy coating. It was found that the laser cladding Co-based alloy/FiC/CaF2 coatings on copper had good friction-reducing and antiwear abilities at temperature up to 400 degrees C. The composite coating obviously decreased friction coefficient and wear rate as the volume fraction of CaF2 increased and TiC decreased. The laser cladding Co-based alloy/20% TiC/10% CaF2 (vol.) composite coating was characterized by mild adhesion wear and plastic deformation and relatively smooth wear surface could be observed. (C) 2013 Elsevier B.V. All rights reserved.