The Johns Hopkins University

Michael Reiss

Timothy P Weihs

Omar Knio

David Van Heerden

Todd Hufnagel

Howard S Feldmesser

Albert Joseph Swiston, Jr

Reactive foils and their uses are provided as localized heat sources useful, for example, in ignition, joining and propulsion. An improved reactive foil is preferably a freestanding multilayered foil structure made up of alternating layers selected from materials that will react with one another in an exothermic and self-propagating reaction. Upon reacting, this foil supplies highly localized heat energy that may be applied, for example, to joining layers, or directly to bulk materials that are to be joined. This foil heat-source allows rapid bonding to occur at room temperature in virtually any environment (e.g., air, vacuum, water, etc.). If a joining material is used, the foil reaction will supply enough heat to melt or soften the joining material, which upon cooling will form a strong bond, joining two or more bulk materials. If no joining material is used, the foil reaction supplies heat directly to at least two bulk materials, melting or softening a portion of each bulk, which upon cooling, form a strong bond. Additionally, the foil may be designed with openings that allow extrusion of the joining (or bulk) material through the foil to enhance bonding.

Methods of making and using freestanding reactive multilayer foils

Reactive foils and their uses are provided as localized heat sources useful, for example, in ignition, joining and propulsion. An improved reactive foil is preferably a freestanding multilayered foil structure made up of alternating layers selected from materials that will react with one another in an exothermic and self-propagating reaction. Upon reacting, this foil supplies highly localized heat energy that may be applied, for example, to joining layers, or directly to bulk materials that are to be joined. This foil heat-source allows rapid bonding to occur at room temperature in virtually any environment (e.g., air, vacuum, water, etc.). If a joining material is used, the foil reaction will supply enough heat to melt the joining materials, which upon cooling will form a strong bond, joining two or more bulk materials.

Reactive multilayer foil with conductive and nonconductive final products

Composite reactive multilayer foil

Freestanding reactive multilayer foils

In accordance with the invention a reactive multilayer foil is fabricated by providing an assembly (stack or multilayer) of reactive layers, inserting the assembly into a jacket, deforming the jacketed assembly to reduce its cross sectional area, flattening the jacketed assembly into a sheet, and then removing the jacket. Advantageously, the assembly is wound into a cylinder before insertion into the jacket, and the jacketed assembly is cooled to a temperature below 100&deg; C. during deforming. The resulting multilayer foil is advantageous as a freestanding reactive foil for use in bonding, ignition or propulsion.

Method of making reactive multilayer foil and resulting product

Growing community of inventors

Baltimore, MD, United States of America

Michael Reiss