Electrical and mechanical properties of multi-walled carbon nanotube reinforced Al composite coatings fabricated by high velocity oxygen fuel spraying

Multi-walled carbon nanotube (MWCNT) reinforced Al composite powders were deposited using a high velocity oxygen fuel (HVOF) spraying process to form coatings. High thermal energy and physical contact with atmospheric oxygen were supplied as the MWCNT/Al composite particles were exposed to a gas flow field of high temperature (~ 3.0 × 103 K) during HVOF spraying. As a result, the particles underwent full or partial melting and rapid solidification during deposition. Large fraction of lamellar structure was formed in the HVOF sprayed coatings due to the low melting point of Al. The high temperature environment and the exposure to oxygen induced the interfacial reaction of MWCNTs within the splats. The electrical and mechanical properties (elastic modulus and micro-hardness) of the MWCNT/Al composite coatings were evaluated. The variations of measured properties of the MWCNT/Al composite coatings were related to the contribution of the remaining MWCNT and the typical lamellar structure. In this study, the relationship among the properties, structure and the interaction of the MWCNTs with the Al matrix is experimentally and theoretically discussed.

► The MWCNT/Al composite coatings were fabricated by HVOF process. ► Microstructure and MWCNT states in the composites were characterized. ► Electrical and mechanical properties of the composite coatings were evaluated. ► Relationship between microstructural factors and properties were investigated.