Method Of Making Reactive Composite Materials and Resulting Products

Abstract

Novel reactive composite materials and associated methods for making the same which are pertinent to numerous new or improved applications. The method for making the reactive composite materials utilizes mechanical deformation to manufacture such materials with controlled, predictable characteristics. In the first deformation step, an assembly of reactive layers and / or particles is plastically deformed to reduce its cross sectional area by one-half or more. Portions of the deformed sheets are stacked or bent into a new assembly, and the new assembly is then deformed. The steps of assembly and deformation are repeated a sufficient number of times that the resulting materials are only locally layered but have relatively uniform reaction velocity and heat generating characteristics predictable by stochastic models derived herein.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The present application is related to, and claims priority from, U.S. Provisional Patent Application Ser. No. 61 / 020,542 filed on Jan. 11, 2008, and which is herein incorporated by reference.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH[0002]The United States Government has certain rights in this invention pursuant to Award 70NANB3H3045 supported by NIST.BACKGROUND OF THE INVENTION[0003]This invention relates to locally layered reactive composite materials, and, in particular, to a method of making such composite materials using mechanical deformation. It also concerns the resulting products and their applications.[0004]Reactive composite materials (“RCMs”) are useful in a wide variety of applications requiring the generation of intense, controlled amounts of heat in a localized region. Reactive composite materials typically comprise two or more phases of materials, spaced in a controlled fashion throughout the composite in uniform or ...

AI Technical Summary

Benefits of technology

[0012]Briefly stated, the present disclosure provides new reactive composite materials and a variety of new ways of making these reactive composite materials, as well as methods for controlling the properties and characteristics of the materials that are pertinent to numerous new or improved applications. In one embodiment, the method for making the reactive composite materials utilizes mechanical deformation to produce materials with controlled, predictable characteristics useful in a variety of applications, where process parameters are well correlated with the micro-structural properties of the resulting product, and wherein the resulting RCM product has a selectable propagation velocity, together with a phenomenological model that captures the dependence of the reaction velocity on the non-uniform layering of the same materials. Another aspect of the present disclosure provides a suitable approach to overcome manufacturing embrittlement of the resulting RCM, and thus enable large-scale, cost-effective mechanical formation of multilayer structures.

[0013]In accordance with the present disclosure, reactive composite materials are fabricated by a series of mechanical deformation steps. In the first deformation step, an assembly of reactive layers and / or particles is plastically deformed to reduce its cross sectional area by one-half or more. This initial deformation substantially eliminates the tendency of deformed layers to delaminate and eliminates the necessity of using specially cleaned metal layers. Portions of the deformed sheets are stacked or bent into a new assembly, and the new assembly is then deformed. The steps of assembly and deformation are repeated a sufficient number of times that the resulting materials are only locally layered but have relatively uniform reaction velocity and heat generating characteristics predictable by stochastic models derived herein. The resulting product is a controllable, locally layered reactive composite material (LLRCM) that can be fabricated quickly and is useful in a wide variety of applications.

Problems solved by technology

This fabrication of the rolled foils was time consuming and difficult.

In addition, the manual folding of sheet stock does not easily lend itself to large-scale production.

However, when many metal layers are rolled at once, these layers tend to delaminate, causing degradation of the resulting foil.

Such separation also permits undesirable oxidation of interlayer surfaces and impedes unification of the layers by cold welding.

Moreover repeated rolling passes tended to distort the layered structures in ways not then predictable, producing necking, elongation or rupture in individual layers, changing the relative thicknesses of the layers, decreasing the ductility of the resulting foil and, significantly, preventing the fabrication of a foil with prescribed reaction velocity and heat generating characteristics.

However, because physical vapor deposition builds foils atom by atom or molecule by molecule, it is not well-suited to the formation of thick layers and thick foils.

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