Negative Poisson’s ratio structures produced from zirconia and nickel using co-extrusion

Objects with a complex structure designed to display negative Poisson’s ratio were produced from zirconia ceramic and from metallic nickel. The objects were arrays of repeat units with designed elastic behavior. The technique of microfabrication by coextrusion, based on oxide powders blended with thermoplastics, was used to replicate and miniaturize single 38 mm repeat unit to obtain an array of 64 units, 400 lm in size. The metallic nickel objects were produced fabricating nickel oxide, followed by sintering in a reducing atmosphere to yield dense metallic nickel. Poisson’s ratio of the nickel structure was –0.3.