High-velocity impact studies of honeycomb sandwich structures with Al/Al2O3 and Al/B4C functionally graded plasma sprayed faceplates

High-velocity impact response of honeycomb sandwich structures (HSS) with Al/Al₂O₃ and Al/B₄C functionally graded plasma-sprayed (FGPS) faceplates are investigated in present work. FGPS structures improve the specific material properties and make the structure distinct from the substrate material. The metal and ceramic content was varied across the thickness of the FGPS coating in the present work. The HSS having honeycomb core sandwiched between two Al/Al₂O₃ FGPS faceplates were manufactured initially. Further, HSS having honeycomb core sandwiched between two Al/B₄C FGPS faceplates were manufactured. Such HSS are repeatedly impacted with a spherical projectile using a single-stage gas gun at a constant impact energy of 260 J, and the results are quantified and compared. The central deflection and dent diameter of FGPS plates as well as HSS were determined, and they increased with the number of impacts. The HSS’s energy absorption was dissipated by top faceplate indentation and core compression. The incorporation of a core prevented FGPS coating delamination and top faceplate penetration. The Al/Al₂O₃ and Al/B₄C FGPS faceplates had dent diameters that were 14.30% and 18.70% smaller than the non-coated Al 6061-T6 faceplate, respectively, which proves the enhancement of high-velocity impact resistance through FGPS coating. The central deflection and dent diameter of the Al/B₄C FGPS HSS are 6.04% and 3% lesser than the Al/Al₂O₃ FGPS HSS, respectively. The energy absorption of the Al/B₄C FGPS HSS is better than that of the Al/Al₂O₃ FGPS HSS. As a result, the present research enhances the knowledge on the impact energy absorption of two distinct FGPS coated plates and HSS, which is highly useful in aerospace and defence applications.