Effect of ceramic coating on carbon nanotubes interaction with matrix material and mechanical properties of aluminum matrix nanocomposite

Using a metalorganic chemical vapor deposition (MOCVD) technique and a tungsten hexacarbonyl W(CO)6 as a precursor, a stable and continuous coating consisting of nonstoichiometric WC1-x nanoparticles with sizes from 10 to 30 nm on the surface of multi-walled carbon nanotubes (CNTs) was obtained. The resulting hybrid WC1-x/CNTs structures had a developed surface morphology, which contributed to a more complete realization of the potential of the physical and mechanical properties of CNTs when used as reinforcement in composite materials. Comparative assessment of aluminum matrix nanocomposites AA5049 + 5 wt% CNTs and AA5049 + 5 wt% WC1-x/CNTs obtained by high energy ball milling and subsequent hot consolidation at 450°С shows that the WC1-x ceramic coating on the carbon nanotubes surface acts as a barrier layer at the interface, preventing the Al4C3 in situ formation at the matrix/CNT boundary. Coating of carbon nanotubes with WC1-x nanoparticles leads to a significant increase in the physical and mechanical properties of aluminum matrix nanocomposites, in particular, to an increase in the compressive strength from 810 ± 8 MPa to 893 ± 7 MPa, fracture deformation from 3.7% to 4.9%, Young's modulus from 102 ± 6 GPa to 110 ± 4 GPa, and microhardness from 152 ± 6 HV to 176 ± 8 HV in comparison with using of CNTs in the as-synthesized state.