Metal matrix composites reinforced with carbon nanotubes by an alternative technique

The metal matrix composites (MMCs) have been used in several applications where high specific resistance and temperature are required for some uses in the aerospace and aeronautic industry. In general, these composites are manufactured using as reinforcing material particles or some fibers like glass, ceramic and carbon fibers. Recently a new manufacturing process for the production of MMCs reinforced with carbon nanotubes, known as sandwich technique has been proposed. This technique produces materials comprised of a metallic matrix and banded structured-layers of multiwall carbon nanotubes (MWCNTs). However, among other issues, the matrix-reinforcement interface and the reinforcement dispersion degree are still open questions. The present study has been aimed on the reinforcement of magnesium sheets with MWCNTs by the sandwich technique. Field emission scanning electron microscopy was used to demonstrate that the method is capable of producing a good dispersion of the MWCNTs with no evidence of damage. The mechanical properties were measured by tensile and nanoindentation tests; yield and ultimate strengths, elastic modulus and hardness were increased with respect to the unreinforced material.