This study explores the individual and combined reinforcement effects of graphene nanoplatelets (GNP) and micro-boron carbide (µB4C) in cold-sprayed Al matrix composite coatings. High energy ball milling was used to create compositions of 2 vol.% GNP, 2 vol.% µB4C, and one of 1 vol.% GNP with 1 vol.% µB4C. All reinforced compositions consisted of a total of 2 vol.% reinforcement to compare the effectiveness of single and dual reinforcement and not the amount of total reinforcement. Coatings were heat treated for 1 h at 400◦C to improve coating densification. Each coating was evaluated using microhardness tests, nanoindentation, dry-sliding wear tests, and adhesion tests. The coatings were also qualitatively evaluated using optical and scanning electron microscopy. All three reinforced coatings experienced a greater than 47% increase in microhardness after heat treatment than the control Al coating. Adhesion testing revealed that 2 vol.% µB4C and the dual-particle coatings had a 40% and 29% increase in adhesion strength, respectively. Most notably, nanoindentation showed that the dual-particle coating experienced a 17% increase in hardness and a 13% increase in elastic modulus compared to the unreinforced coating. The singly reinforced coatings either had the same or lower hardness and elastic modulus than the unreinforced coating.ONR, Washington DC, 22217Outstanding ThesisEnsign, United States NavyApproved for public release. Distribution is unlimited
