Effect of carbon nanotube addition on morphology of SHS synthesized materials

During the past few years, a considerable amount of research has been focused on the addition of carbon nanotubes (CNTs) to various matrix materials including polymers, ceramics, metals, and intermetallics. However, the processing methodologies for ceramics, metals, and intermetallics have been primarily those used in traditional power technology. In this paper combustion synthesis (CS), also known as self-propagating high temperature synthesis (SHS) or volume combustion synthesis (VCS) was explored as a route for the formation of carbon nanotube reinforced composites. The effect of single-walled carbon nanotube (SWCNT) addition on the product morphology is presented for the following reactive systems: (i) Ni-Al and (ii) 3Ti-B4C. It was determined that the SWCNTs survive a short exposure to the high temperatures associated with the combustion synthesis of NiAl (1911 K) and TiB2-TiC (3200 K) and effectively act as a diluent which results in grain refinement of the resulting product. The results also show that effective dispersion of the SWCNTs is achieved; however, the SWCNTs are not well embedded in the matrix. Based on the survival of the SWCNTs in the above reactive systems it was shown that metal coated nanotubes may be a very promising reinforcement material for combustion synthesized materials and could effectively solve the issue of CNT to matrix adhesion.