Patterned Reactive Materials for Controlled Chemical Time Delay

Solution Overview

Problem

Existing reactive materials for self-propagating, exothermic reactions have high propagation velocities and rely on environmentally hazardous materials, necessitating the development of patterned reactive materials with controlled discontinuities to manage propagation rates effectively.

Innovation Solution

The use of patterned reactive materials with controlled breaks connected by inert materials, varying thickness, and deposition on substrates with low thermal conductivity to manipulate propagation rates, creating a chemical time delay with reproducible and controlled ignition times ranging from microseconds to seconds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If vapor-deposited reactive materials are used for self-propagating reactions, then environmental friendliness is improved, but propagation velocity becomes too high

Engineering Contradiction:

Improveenvironmental hazardVSAvoidpropagation velocity

Core Design Contradiction:

Object-affected harmful factorsVSSpeed

Solution Approach 1:

The reactive material is divided into discrete segments separated by inert material barriers. This segmentation prevents continuous propagation, forcing the reaction to restart at each segment interface, thereby reducing overall propagation velocity while maintaining the environmentally friendly vapor-deposited material composition

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An inert material is introduced as an intermediary between reactive material segments. This intermediary layer acts as a barrier that temporarily halts propagation, requiring heat transfer and re-ignition to continue the reaction, thus controlling propagation velocity without compromising the environmental benefits of the reactive material composition

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If patterned breaks are introduced in reactive material to control propagation, then propagation rate control is improved, but device complexity increases

Engineering Contradiction:

Improvepropagation rate controlVSAvoidpatterned structure complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The reactive material is divided into discrete segments separated by inert material barriers. This segmentation prevents continuous propagation, forcing the reaction to restart at each segment interface, thereby reducing overall propagation velocity while maintaining the environmentally friendly vapor-deposited material composition

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The thickness of the inert material barrier is varied to precisely control the propagation delay characteristics. By adjusting this geometric parameter, the propagation rate can be tuned without fundamentally changing the overall device architecture or material composition

Inventive Principle:

Principle #35Parameter changes

3Speed

If reactive material thickness is varied to manipulate propagation rate, then propagation control is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improvepropagation rate manipulationVSAvoidthickness control precision

Core Design Contradiction:

SpeedVSManufacturing precision

Solution Approach 1:

The thickness of the inert material barrier is varied to precisely control the propagation delay characteristics. By adjusting this geometric parameter, the propagation rate can be tuned without fundamentally changing the overall device architecture or material composition

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The vapor-deposition process inherently provides uniform and controlled thickness through self-limiting growth mechanisms. The reactive and inert materials are deposited in alternating layers with precise thickness control achieved through timing and process parameters, reducing the need for additional precision manufacturing steps

Inventive Principle:

Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach allows for controlled and efficient propagation of exothermic reactions, achieving a balance between time delay and heat transfer efficiency, ensuring self-propagation without quenching, and providing an environmentally friendly solution.

Implementation Method 1

Self-propagating, exothermic reactions in powder compacts are commonly used as chemical time delays

Methodology Applied

Scientific EffectExothermic reaction: Exothermic Reaction

Implementation Method 2

deposition on substrates with low thermal conductivity to manipulate propagation rates

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentUS10815161B2Reactive materials for manipulating propagation rates and a resulting chemical time delay

Publication Date: 2020.10.27 JOHNS HOPKINS UNIVERSITY

AI summary

The present invention is directed to embodiments of reactive material (RM) and an associated chemical time delay that includes an RM, according to an embodiment of the present invention. One embodiment includes a delay material that is an RM patterned on a substrate using lithographic techniques. Another embodiment includes a delay material that is an RM deposited on a patterned substrate such as a mesh. The present invention also includes a chemical time delay that includes either embodiment of the delay material, or any variation on the delay material that would be known to or conceivable to one of skill in the art.