Plasma Etching for Cryogenic Tank Surface Preparation
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Solution Overview
Problem
Current methods for preparing the surface of cryogenic tanks, such as chemical pickling followed by primer deposition, are costly, generate pollutants, and require extensive workshop space, while existing plasma surface treatment methods are not effectively accessible for all areas, especially grooves in the tank.
Innovation Solution
A plasma gas beam is used to strip the surface of the tank, followed by the application of a primer material and subsequent bonding of thermal insulation or support layers, utilizing a scanning speed and gas composition that ensures effective adhesion and protection without the drawbacks of traditional methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical pickling is used to treat the surface, then adhesion properties are improved, but cost increases and polluting effluents are generated
Solution Approach 1:
The patent replaces chemical pickling with plasma treatment, substituting a chemical process with a physical plasma-based process. The plasma beam (generated from gases like argon, nitrogen, or air) physically etches and activates the aluminum alloy surface through ion bombardment and reactive species, achieving comparable or superior adhesion properties without generating chemical effluents. This resolves the contradiction by maintaining reliability while eliminating harmful chemical waste.
Solution Approach 2:
The patent changes the fundamental parameter of surface treatment from chemical to physical plasma processes. By controlling plasma parameters (gas composition, power, pressure, exposure time), the surface achieves the necessary adhesion properties through physical mechanisms like etching and activation rather than chemical reactions, thereby avoiding polluting effluents while maintaining or improving adhesion.
2Reliability
If chemical pickling is used to treat the surface, then adhesion properties are improved, but workshop space requirements increase
Solution Approach 1:
The patent replaces the chemical pickling process with a plasma beam treatment system that can be applied in-situ or in compact equipment. The plasma beam delivery system requires minimal workspace compared to chemical pickling facilities that need large areas for chemical storage, application, and effluent handling. This substitution resolves the contradiction by maintaining adhesion properties while dramatically reducing workshop space requirements.
3Object-generated harmful factors
If plasma treatment is used to strip the surface, then cost is reduced and environment is protected, but accessibility to all areas including grooves is limited
Solution Approach 1:
The patent employs a dynamic plasma beam delivery system where the plasma source and/or workpiece can move relative to each other, allowing the plasma beam to access complex geometries including grooves and hard-to-reach areas. The plasma beam can be scanned across the surface or directed into recesses, providing uniform treatment throughout. This dynamic approach resolves the contradiction by maintaining environmental friendliness while achieving complete accessibility to all surface areas.
4Reliability
If traditional surface treatment is used, then adhesion is achieved, but structural integrity may be compromised
Solution Approach 1:
The patent carefully controls plasma treatment parameters (power density, exposure time, gas composition, pressure) to achieve sufficient surface activation and etching for adhesion while avoiding excessive material removal or structural damage. By optimizing these parameters, the plasma process achieves the necessary adhesion properties without compromising the structural integrity of the aluminum alloy tank, resolving the contradiction between adhesion and strength.
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 plasma etching method provides a cost-effective, environmentally friendly surface treatment that maintains the structural integrity and adhesion properties of the tank, with improved breaking strength and resistance to corrosion, while being accessible to all areas, including grooves, and does not alter the microstructure of the tank material.
Implementation Method 1
A plasma gas beam is used to strip the surface of the tank
Implementation Method 2
via bombardment of the surface with a plasma gas beam of ionized gas
Implementation Method 3
a layer (5) of primer is applied... after the step of depositing layer (5) of primer bonding material, a layer (6) of thermal insulation... can be glued onto layer (5) of primer bonding material
Data Source
Figure 1~5
AI summary
The invention relates to a method for preparing a surface (2) of a cryogenic tank (1) of a space launch vehicle, the tank (1) consisting of at least one wall (2) made of an aluminium alloy, in which at least part of the surface of the wall (2) is subjected to etching, characterised in that the etching includes etching by plasma technology, i.e. by bombardment of the surface with a plasma gas beam of ionised gas.