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Effect of Carbon Nanotube (CNT) Inclusion on the Microstructure and Performance of a Laser Clad TiC Coating
B.F. He, F. Ma, D.Y. Ma and K.W. Xu

The effects of carbon nanotube (CNT) inclusion on the microstructure and performance of a TiC coating on a Ti-6Al-4V substrate brought about by laser cladding were studied. Mixing produced TiC+CNT powders with CNT concentrations of 2.5% CNTs, 5.0% CNTs and 7.5% CNTs. The microstructure and phase compositions were identified by scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS) and X-Ray diffraction (XRD). The wear resistance was indicated by the friction wear testing machine. The results showed that the binding interfaces of the substrate and the laser clad coating were all combined closely and there was no euphotic zone. The main microstructure of the coating was dendritic and rod-like or granuliform structures. The XRD pattern showed that the coatings which mainly consisted of TiC, VC and α-Ti, some of the Ti3AlC2 phase was found in the 5.0% CNTs addition coating. The wear mechanism of the coatings was abrasive wear and oxidation and the wear mechanism of substrate was plastic deformation, ploughing grooves and oxidation. The wear rates of the coatings were 3.9 × 10-7 mm3/Nm for the TiC+2.5% CNT addition, 5.92 × 10-7 mm3/Nm for the TiC+5.0% CNT addition and 4.57 × 10-7 mm3/Nm, for the TiC+7.5% CNT addition, which were smaller than that of the Ti-6Al-4V substrate at 7.83 × 10-7 mm3/Nm.

Keywords: Laser cladding, carbon nanotube (CNTs), microstructure, hardness, wear resistance

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