Salt Additive for Solid Rocket Motor Thermal Stability
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Solution Overview
Problem
Solid rocket motors face thermal instability due to thermal decomposition of perchlorate oxidizers, leading to potential foaming and increased reaction surface area, which can cause premature burning, explosion, or detonation under elevated ambient temperatures.
Innovation Solution
Incorporating a salt compound, such as a cobalt or boron-based metal salt, that is reactive with perchlorate decomposition products, thereby sequestering these products and reducing foaming, with the salt compound comprising 0.1% to 20% of the total weight of the fuel, binder, and oxidizer, enhancing thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If perchlorate oxidizer is used in solid rocket motor, then high energy performance is achieved, but thermal instability occurs due to decomposition at elevated temperatures
Solution Approach 1:
A salt compound (such as cobalt chloride, boron tribromide, or boron trichloride) is introduced as an intermediary substance that reacts with perchlorate decomposition products (ammonia, chlorine, oxygen) to form stable compounds. This mediator prevents the decomposition products from causing foaming and secondary reactions, thereby maintaining thermal stability while preserving the high energy performance of the perchlorate oxidizer.
Solution Approach 2:
The invention converts the harmful effect of perchlorate decomposition (which produces reactive gases causing foaming and instability) into a beneficial outcome by providing salt compounds that selectively react with these decomposition products. The harmful decomposition gases are transformed into stable reaction products, eliminating the thermal instability problem while maintaining the energy benefits of perchlorate.
2Quantity of substance
If perchlorate oxidizer decomposes at elevated temperatures, then gas generation occurs, but foaming and increased reaction surface area lead to premature burning or explosion
Solution Approach 1:
The salt compound acts as a mediator that intercepts perchlorate decomposition products (ammonia, chlorine, oxygen) before they can cause foaming. By reacting with these gases to form stable compounds, the salt prevents the accumulation of gas bubbles and the formation of foam, thereby eliminating the increased reaction surface area that would lead to premature burning or explosion.
Solution Approach 2:
The salt compound is pre-positioned in the propellant formulation to provide preliminary anti-action against the harmful effects of perchlorate decomposition. Before the decomposition products can cause foaming and initiate premature burning, the salt compounds are already present to react with and neutralize them, preventing the harmful sequence of events from occurring.
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 reactive salt compound enhances thermal stability by spontaneously reacting with perchlorate decomposition products, reducing the likelihood of premature ignition and improving the motor's resistance to temperature-induced failures during storage and transport.
Implementation Method 1
a salt compound that is reactive with one or more of the perchlorate decomposition products... The reactive salt compound enhances thermal stability by spontaneously reacting with perchlorate decomposition products
Implementation Method 2
a perchlorate oxidizer that is thermally decomposable to perchlorate decomposition products
Data Source
Figure 1~3
AI summary
A solid rocket motor includes a fuel, a binder, a perchlorate oxidizer that is thermally decomposable to perchlorate decomposition products, and a salt compound that is reactive with one or more of the perchlorate decomposition products.