Microstructural Features and Mechanical Properties of Multi-walled Carbon Nanotube Reinforced Metal Matrix Composite Coatings Fabricated by Kinetic and Thermal Spray Technologies

Various metal matrix composites (MMCs) (Al, Cu, Ni, and Ti) reinforced with multi-walled carbon nanotubes (MWCNTs) were fabricated by kinetic and thermal spray technologies. Mechanical properties, e.g., elastic modulus, micro-hardness and wear resistance, of MWCNT reinforced MMCs were evaluated. Furthermore, relationships among the mechanical properties of the MMCs, characteristics of spray processes, and contribution of the MWCNTs to matrix strengthening were discussed. The mechanical properties of the MMCs were related to contribution of MWCNTs, i.e., interaction of the MWCNTs with matrix materials. The contributions of MWCNTs to improvement in mechanical properties are based on elastic wave scattering, Orowan looping, and anchoring or bridging mechanisms in such manner that they interact with elastic and plastic stress propagated from the metal matrix; thus, their fraction in the MMCs and interaction with the metal matrix are key factors that tailor the mechanical properties of the MMCs. In this study, the interaction and contribution of the MWCNTs to MMCs are understood microstructural and physical metallurgical analysis.