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AssigneeInternational Business Machines Corporation
InventorsGareth G. Hougham, Xiao H. Liu
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Bilayer platelet fillers are employed to compensate for a positive coefficient of thermal expansion (CTE) of an embedding polymeric material, or even to provide a composite structure having a negative CTE to eliminate or alleviate thermomechanical stress and/or delamination during thermal cycling. A bilayer platelet includes two joined layers having different CTEs. The CTE mismatch induces bending of the bilayer platelets, thereby causing cavities at temperatures lower than the joining temperature at which the bilayers are joined. The decrease in the volume of the polymeric material and the bilayer platelets at low temperatures is compensated by an accompanying increase in the volume of the cavities so that the composite structure has a temperature independent volume, a low net CTE, or even a negative CTE.
A composite structure comprising a polymeric matrix and at least one bilayer platelet embedded therein, wherein each of said at least one bilayer platelet comprises a pair of material layers joined to each other and having mismatched coefficients of thermal expansion (CTEs), wherein at least one cavity is present between each of said at least one bilayer platelet and said polymeric matrix in a temperature range within which surfaces of said at least one bilayer platelet have a non-zero curvature.
A method of forming a composite structure comprising a polymeric matrix and at least one bilayer platelet embedded therein, said method comprising:
Dependencies are inferred from the claim text.