Binder-Free Pyrotechnic Grains for Low-Pressure Gas Generation
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Solution Overview
Problem
Existing pyrotechnic grains for long-duration, low-flow rate gas generation face challenges in achieving a slow combustion rate, low porosity, and suitable mechanical behavior without the use of binders, which are critical for applications in automotive safety and aeronautics, especially under extreme temperature conditions.
Innovation Solution
The development of binder-free, large-dimension pyrotechnic grains composed of specific oxidizing and reducing charges, primarily basic copper nitrate and guanidine nitrate, with controlled porosity and compacting methods to produce cylindrical blocks with low porosity and enhanced mechanical properties, allowing for a slow combustion rate and stable performance across varying temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If binder-free pyrotechnic grains of large dimensions are used, then combustion period is extended and mechanical behavior is improved, but porosity increases leading to unacceptable ballistic properties
Solution Approach 1:
The patent changes the physical and chemical parameters of the pyrotechnic composition, specifically using a binder-free formulation with controlled particle size distribution and compacting under high pressure (100-1000 MPa) to achieve low porosity (5-15%) in large grains while maintaining slow combustion rate and acceptable mechanical properties
Solution Approach 2:
The patent employs a composite pyrotechnic composition consisting of multiple components (oxidizer, fuel, binder-free matrix) with specific particle size distributions that, when compacted together, create a dense structure with controlled porosity that enables both large grain dimensions and acceptable ballistic properties
2Strength
If binder-free pyrotechnic grains are used, then mechanical behavior is improved for vibratory environments, but porosity increases affecting combustion rate control
Solution Approach 1:
The patent applies extreme pressure (100-1000 MPa) during compacting to dramatically reduce porosity in binder-free grains, transforming the mechanical structure to achieve both improved strength for vibratory environments and controlled porosity for combustion rate management
3Duration of action of moving object
If large grain dimensions are used, then combustion period is extended, but combustion surface area decreases affecting gas generation rate
Solution Approach 1:
The patent creates local quality variations within the grain structure through controlled porosity distribution and particle size arrangement, enabling the large grain to maintain adequate combustion surface area in specific regions while overall dimensions extend the combustion period
4Adaptability or versatility
If pyrotechnic grains operate under extreme temperature conditions, then application range is extended, but combustion rate becomes highly dependent on temperature
Solution Approach 1:
The patent selects chemical components and ratios (oxidizer, fuel, additives) whose combustion characteristics remain relatively stable across extreme temperature ranges (-60°C to 110°C), and uses high-pressure compacting to create a dense structure that minimizes temperature-dependent porosity effects on combustion rate
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 resulting pyrotechnic grains provide a long combustion period, low porosity, and improved mechanical behavior, ensuring reliable gas generation with low toxicity and minimal particle or corrosive species production, suitable for extended operational periods and extreme environments.
Implementation Method 1
the combustion of said grains
Data Source
Figure 1~2
Figure 3
AI summary
The present invention provides pyrotechnic grains of composition comprising at least one oxidizing charge and at least one reducing charge and no binder. In characteristic manner, said grains are in the form of substantially cylindrical blocks: with a thickness of more than 5 mm; with an equivalent diameter of 10 mm or more; and with porosity in the range 1% to 8%, limits included. Said grains, advantageously based on guanidine nitrate and basic copper nitrate, are suitable for the slow, low-pressure generation of gas over an extended period.