Composite Solid Propellant Crosslinking via Bismuth Catalyst
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Solution Overview
Problem
Current composite solid propellants with polyurethane binders require lengthy and costly crosslinking processes at high temperatures, leading to significant thermal shrinkage and increased material investments, which are undesirable for rocket engine propulsion systems.
Innovation Solution
A catalytic system using organic bismuth salts for crosslinking liquid polyol polymers at lower temperatures, maintaining the properties of the resulting propellant while reducing crosslinking time and thermal shrinkage, and incorporating ammonium perchlorate and aluminum as oxidizing and reducing charges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If crosslinking is carried out by heating the propellant paste to a temperature of approximately 50°C for 10 days, then the propellant achieves proper crosslinking and structural integrity, but the process incurs significant heating costs, requires substantial heating equipment investments, and causes substantial thermal shrinkage
Solution Approach 1:
The invention changes the temperature parameter from conventional 50°C to a lower range of 20-40°C, and modifies the time parameter from 10 days to a shorter duration. This is achieved by introducing a catalyst system comprising at least one catalyst from the group consisting of organometallic compounds of tin, bismuth, and zinc, which accelerates the crosslinking reaction at lower temperatures, thereby reducing heating costs and energy consumption while maintaining structural integrity
Solution Approach 2:
The invention introduces a catalyst system as an intermediary substance that mediates the crosslinking reaction. The catalyst, selected from organometallic compounds of tin, bismuth, and zinc, facilitates the crosslinking process at lower temperatures by lowering the activation energy barrier, enabling the reaction to proceed efficiently without requiring substantial heating equipment or incurring high heating costs
2Reliability
If crosslinking is carried out by heating the propellant paste to a temperature of approximately 50°C for 10 days, then the propellant achieves proper crosslinking, but the process requires substantial heating equipment investments
Solution Approach 1:
The invention changes the temperature parameter from conventional 50°C to a lower range of 20-40°C, which reduces the thermal gradient and heat transfer requirements. This parameter change allows the use of simpler, less expensive heating equipment while still achieving proper crosslinking quality through the catalytic acceleration of the reaction at lower temperatures
3Reliability
If crosslinking is carried out by heating the propellant paste to a temperature of approximately 50°C for 10 days, then the propellant achieves proper crosslinking, but the process causes substantial thermal shrinkage and increases specifications on the design of the propellant loading
Solution Approach 1:
The invention changes the temperature parameter from conventional 50°C to a lower range of 20-40°C, which reduces thermal expansion and contraction during the crosslinking process. This lower temperature regime minimizes thermal shrinkage of the propellant paste, thereby reducing the harmful thermal effects and relaxing the design specifications for propellant loading containers and structures
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 simplifies propellant manufacturing, saves energy, and maintains mechanical properties, enabling efficient production of composite solid propellants suitable for rocket engines like the Ariane 5, with reduced thermal shrinkage and combustion instabilities.
Implementation Method 1
at least one crosslinking catalyst chosen from among the organic salts of bismuth
Implementation Method 2
crosslinking a liquid polyol polymer in the presence of at least one crosslinking agent of the polyisocyanate type
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a composite solid propellant containing, in a crosslinked inert polyurethane binder, an oxidizing charge of ammonium perchlorate and optionally a reducing charge of aluminum, the inert binder being crosslinked with an organic bismuth salt.