Mechanical properties of ceramics reinforced with allotropic forms of carbon

For decades, enormous investigation effort has been devoted to the fabrication of new ceramic matrix composites with enhanced mechanical properties. One of the most explored strategies is the addition of carbon allotropic phases such as carbon nanotubes, graphene, and carbon nanofibers due to their outstanding properties. In this review, the main fabrication protocols considered for the synthesis of the ceramic composites based on alumina and zirconia are shown, and their mechanical properties and the changes achieved by the addition of carbon allotropes are presented and discussed. Under particular circumstances, significant improvements in properties such as fracture toughness and wear at low temperature, or creep behavior and superplasticity at high temperature have been accomplished. Nevertheless, some critical aspects such as the homogenization of the carbon allotropes within the matrix are still lacking consolidated responses, which suggest that the potentialities of this reinforcing strategy have not yet been completely exploited. In summary, this work collects the fabrication strategies, major results, and main controversies of two decades of scientific research on the improvement of the fabrication methods and mechanical properties of ceramic matrix composites.