Patent ID: 8624152

Claim:
A negative coefficient of expansion-engineered element or particle, comprising: two layers of a sheet material in surface contact with each other, each said layer comprising two superimposed sheets having differing coefficients of thermal expansion forming a bilayer; said bilayers being laser welded about an enclosing path so as to produce a closed structure; said bilayer sheets further being laser cut in a path extending externally of said laser welded path to separate said closed structure from the remaining bilayer sheets; and said closed structure being responsive to a cooling action whereby said different coefficients of thermal expansion of said bilayers causes said closed structure to assume a volume, wherein each said bilayer is initially formed from superimposed sheets constituted of identical metallic material, each said sheet having the contiguous surfaces thereof oxidized to a half-thickness of the respective sheet subsequent to being laser welded so as to form said closed bilayer structure.