Expandable Graphite Pyrotechnic Composition for High Burn Rate
Solution Overview
Problem
Conventional pyrotechnic dummy targets with internal combustion channels are inefficient in burning rate, limiting their ability to function as effective kinematic targets, as they burn at a maximum speed of 12 mm/s, whereas a burn rate of at least 30 mm/s is required to maintain a 5-second burn time, and known combustion catalysts like ferrocene only accelerate combustion by 20%.
Innovation Solution
A pyrotechnic active composition comprising a fuel, an oxidizing agent, and a combustion accelerating agent in the form of expandable particles that increase the burning surface area through physical expansion, allowing for significantly higher burn-off rates without chemical reaction, which can be combined with other catalysts and used in forehead burner designs to maximize volume utilization and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional combustion catalysts like ferrocene are used, then combustion is accelerated by around 20%, but the burn rate remains insufficient for forehead burner designs requiring at least 30 mm/s
Solution Approach 1:
The patent changes the physical state and thermal properties of the combustion catalyst by using expandable graphite that transforms from a compact solid to an expanded porous structure during combustion. This parameter change in volume and porosity dramatically increases the burning surface area, achieving burn rates of 30 mm/s or more, far exceeding the 20% acceleration provided by conventional catalysts like ferrocene.
Solution Approach 2:
The patent utilizes the phase transition of expandable graphite, which undergoes a dramatic volume expansion (up to 200 times) when heated. This phase transition from compact graphite to expanded graphite creates a highly porous structure that vastly increases the combustion surface area, enabling the required burn rates for forehead burner designs without relying solely on chemical catalysis.
2Reliability
If internal combustion channels are used in dummy targets, then combustion can be sustained, but the amount of active mass per unit volume is reduced and the structure becomes more complex
Solution Approach 1:
The patent extracts and eliminates the combustion channel structure from the dummy target design. By using expandable graphite as a combustion accelerator in the active mass itself, the invention enables the active mass to burn efficiently from the surface without requiring internal channels, thereby simplifying the structure while maintaining reliable combustion.
Solution Approach 2:
The expandable graphite particles embedded in the active mass serve as self-contained combustion accelerators. When heated, they automatically expand and increase the burning surface area, enabling the active mass to sustain its own combustion without requiring external combustion channels or additional structural components.
3Device complexity
If the active mass burns from one end face as a forehead burner, then the structure is simpler and more active mass can be accommodated, but the burn rate must be at least 30 mm/s which conventional active masses cannot achieve
Solution Approach 1:
The patent changes the thermal and structural parameters of the combustion process by incorporating expandable graphite. As the graphite expands upon heating, it creates a highly porous structure that dramatically increases the burning surface area, enabling the active mass to achieve burn rates of 30 mm/s or more while maintaining the simple forehead burner configuration.
Solution Approach 2:
The patent creates a composite active mass by combining the fuel composition with expandable graphite particles. This composite material integrates the combustion accelerator directly into the active mass matrix, enabling the simple forehead burner design to achieve the required high burn rate without compromising structural simplicity.
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
The composition achieves burn rates up to 100 mm/s, enhancing the efficiency and reliability of pyrotechnic targets by eliminating the need for internal combustion channels and reducing storage stability concerns, while being cost-effective and easily producible.
Implementation Method 1
a combustion accelerating agent and optionally a binder. The combustion accelerating agent is in the form of particles that are distributed in the active mass, the combustion accelerating agent being a solid that can be expanded by at least a factor of 2 by supplying heat.
Implementation Method 2
By expanding the solid with the addition of heat, the active mass crumbles on the burning surface, so that the burning area is enlarged.
Data Source
AI summary
Pyrotechnic active composition comprises a fuel, an oxidizing agent for the fuel, a combustion acceleration medium and optionally a binder, where the combustion acceleration medium is in the form of particles that are dispersed in the active composition, and is a solid material expandable by the supply of heat around at least one factor of 2.