Multifunctional hybrid composite: Plasma sprayed Al and graphene reinforced alumina coating

Multifunctional composite coatings are essential and challenging to develop, for versatile applications in structural-mechanical components, wear-resistant surfaces, joining, etc. In this perspective, we developed a multifunctional, hybrid Al and exfoliated graphene-reinforced alumina composite coating using atmospheric plasma spraying. We observed the unique microstructural features such as uniform thickness (∼300 μm), phase retention, graphene sandwiching with splats, etc., which offered high-density (>90%) in alumina composite coating. The Alumina-Al-graphene composite coatings exhibited impressive mechanical properties, including high hardness (9–13 GPa), elastic modulus (100–150 GPa), and toughness (2–13 MPam ^0.5) along with exceptional adhesion (∼35 MPa). These coatings offered superior tribological behaviour, wear rate (0.1–1.5 × 10 ⁻⁴ ), COF:<0.5, etc., due to exfoliated graphene, its lubricating capability. Furthermore, the electrical conductivity of these hybrid coatings increased, enabling the metallization of alumina ceramics and facilitating ceramic surface joining. Therefore, our exfoliated graphene-reinforced ceramic-metal, a hybrid composite coating, makes itself an impressive approach for industrial applications.