Structural ceramic coatings in composite microtruss cellular materials

In the present study, anodizing was used to produce Al2O3 coatings in a conventional 3003 aluminum alloy microtruss core; a 38.5 μm thick anodic coating provided a 143% increase in compressive strength. Finite-element analyses were used to illustrate the dependence of the compressive strength and failure mechanism on the thickness of the anodic coating. At low thicknesses the microtruss strength is dictated by global bucking of the internal struts. However, at higher thicknesses the compressive strength is controlled by coating fracture and local deformation in the hinge region of the struts. Regardless of the failure mechanism, the compressive strength of the composite microtruss increased with increasing anodic coating thickness, with very little corresponding weight penalty.

The compressive strength increase per unit sleeve thickness of Al cores reinforced with Al2O3 sleeves is lower than the corresponding strength increase when the same cores are reinforced with nanocrystalline Ni (n-Ni) sleeves (left). However, because anodizing is a transformative surface treatment, the Al2O3 coating was able to achieve this performance increase with little overall weight penalty (right).Figure optionsDownload high-quality image (118 K)Download as PowerPoint slideHighlights
► A new type of metal/ceramic microtruss cellular composite has been created.
► Reinforcing sleeves of Al2O3 were deposited on low density Al microtruss cores.
► Significant compressive strength increases were seen at virtually no weight penalty.
► Failure mechanisms were studied by electron microscopy and finite element analysis.
► Buckling, sleeve wrinkling, and coating fracture dictated the compressive strength.