Periodic Reporting for period 1 - SolCoat (Stray Light Suppression Coating for Additively Manufactured Aerospace Components)
Période du rapport: 2020-11-02 au 2022-03-01
With growing concern over climate change, measurements performed by meteorological satellites, such as the MTG (Meteosat Third Generation) are becoming increasingly necessary. Earth Observation (EO) satellites such as those commissioned by the European Union (Copernicus sentinel missions) for agricultural monitoring, tracking wildfires, and monitoring sea levels carry increasingly complex remote sensing optical instrumentation. These systems require thermo-optical coatings to minimise the stray light entering the instrument, which would otherwise degrade performance. Additionally, next generation communication satellites are incorporating higher power density payloads, which makes regulation of the internal temperatures of satellites more challenging while large volume 'satellite constellations' can impact on scientific observations. These challenges can be met by the development of a robust 'space complaint' thermo-optical coating with high solar absorptance and high thermal emittance.
Conclusions
- A Design of Experiments revealed main influencing parameters which were used in the following development and optimisation of sol-gel formulations.
- A baseline sol-gel prototype was produced based on optimized formulation preparation parameters. The thermo-optical properties, heat resistance, adhesion and outgassing of the baseline coating formulation were analysed, showing good results.
- The curing cycle was optimised.
- An inorganic sol-gel coating formulation based on tetraethyl orthosilicate was developed. The formulation preparation parameters were optimized, and the most relevant properties of the coating were investigated.
- Alternative black pigments were tested, and it was shown that a bone char pigment shows the best thermo-optical characteristics.
- Basic initial dip-coating experiments allowed to estimate the coating application parameters.
- The development of alternative hybrid organic-inorganic sol-gel formulations was initiated, which included optimisation of components ratio and testing of additional cross-linking agent. Two, the most promising formulations, based on epoxy silane and methacrylic silane, were investigated and the thermo-optical properties were measured. These formulations have shown the best results to date and are recommended for the next stages of this project.
- Several representative hardware parts were coated by dip-coating using “5_G” formulation with Cosmic Black pigment. In general, the positive results were achieved but the dip-coating process requires some adjustments to provide more consistent coating thickness.
Conclusions
- A Design of Experiments revealed main influencing parameters which were used in the following development and optimisation of sol-gel formulations.
- A baseline sol-gel prototype was produced based on optimized formulation preparation parameters. The thermo-optical properties, heat resistance, adhesion and outgassing of the baseline coating formulation were analysed, showing good results.
- The curing cycle was optimised.
- An inorganic sol-gel coating formulation based on tetraethyl orthosilicate was developed. The formulation preparation parameters were optimized, and the most relevant properties of the coating were investigated.
- Alternative black pigments were tested, and it was shown that a bone char pigment shows the best thermo-optical characteristics.
- Basic initial dip-coating experiments allowed to estimate the coating application parameters.
- The development of alternative hybrid organic-inorganic sol-gel formulations was initiated, which included optimisation of components ratio and testing of additional cross-linking agent. Two, the most promising formulations, based on epoxy silane and methacrylic silane, were investigated and the thermo-optical properties were measured. These formulations have shown the best results to date and are recommended for the next stages of this project.
- Several representative hardware parts were coated by dip-coating using “5_G” formulation with Cosmic Black pigment. In general, the positive results were achieved but the dip-coating process requires some adjustments to provide more consistent coating thickness.
Initial experiments involved the development of a sol-gel based coating incorporating specialised black pigments used in an existing space coating (SolarBlack). These experiments established the most optimal loading and processing parameters required to achieve good thermo-optical properties but where not robust. The second phase of the project involved altering the sol-gel formulation to provide greater coating stability. This result resulted in the development of a hybrid organic-inoganic formulation which could be further tailored for specific thermo-optical and environmental requirements. This formulations eliminated micro-crack formation observed in early trials through the optimization of cross-linking agents and by optimizing cure profiles a low outgassing material was obtained. While still in a relatively early stage of development these results provide a promising platform to further develop this material for the space sector.
The IA was trained in the following topics
- Manual handling and PPE training Mandatory regular training
- H&S policy training Training on ENBIO Health & Safety policy
- QMS and RPT training Training on ENBIO quality management system, SOPs, projects tracking and data protection regulations
- Green Belt training in innovation engineering (Analysis and solution of system related problems - Innovation based cost reduction - Forecasting the evolution of a system)
- ECSS standards training (The IA received the basic knowledge of ESA materials acceptance and testing regulations, investigated the required procedures for new materials introduction in European Space industry.)
- Various laboratory analytical and coating technicals detailed fully in the pertinent report.
- Innovation and Business Management Core Programme provided by EY Business school (The IA received extensive training in Innovation Management and Business Management, which gave him a lot of necessary skills for implementation in his current and further research and innovation activities. Upon completion of the course, the IA passed the required exam and received a Certificate of Completion.)
Main Results:
Baseline sol-gel coating prototype ("3_3"): 96.65 % (UV/VIS/NIR % abosorptance) 90.51 (% IR emittance)
Inorganis alternative sol-gel ("5_2"): 97.47 % (UV/VIS/NIR % abosorptance) 92.43 (% IR emittance)
Hybrid organic -inorganic sol-gel ("5_M"): 97.11% (UV/VIS/NIR % abosorptance) 92.12 (% IR emittance)
Hybrid organic-inorganic sol-gel (5_G"): 97.56 % (UV/VIS/NIR % abosorptance) 92.03 (% IR emittance)
SolarBlack (for comparison - existing developed coating): 95.04 % (UV/VIS/NIR % abosorptance) 73.61 (% IR emittance)
It can be seen that the alternative formulations, both inorganic and hybrid, show better results than SolarBlack® and baseline “3_3” formulation.
Exploitation:
Work conducted will be report at the next scheduled European Conference on Spacecraft Structures Materials and Environmental Testing in Toulouse, France. Further development will be carried out and prototypes tested with the European Space Agency space research and technology centre (ESTEC).
The IA was trained in the following topics
- Manual handling and PPE training Mandatory regular training
- H&S policy training Training on ENBIO Health & Safety policy
- QMS and RPT training Training on ENBIO quality management system, SOPs, projects tracking and data protection regulations
- Green Belt training in innovation engineering (Analysis and solution of system related problems - Innovation based cost reduction - Forecasting the evolution of a system)
- ECSS standards training (The IA received the basic knowledge of ESA materials acceptance and testing regulations, investigated the required procedures for new materials introduction in European Space industry.)
- Various laboratory analytical and coating technicals detailed fully in the pertinent report.
- Innovation and Business Management Core Programme provided by EY Business school (The IA received extensive training in Innovation Management and Business Management, which gave him a lot of necessary skills for implementation in his current and further research and innovation activities. Upon completion of the course, the IA passed the required exam and received a Certificate of Completion.)
Main Results:
Baseline sol-gel coating prototype ("3_3"): 96.65 % (UV/VIS/NIR % abosorptance) 90.51 (% IR emittance)
Inorganis alternative sol-gel ("5_2"): 97.47 % (UV/VIS/NIR % abosorptance) 92.43 (% IR emittance)
Hybrid organic -inorganic sol-gel ("5_M"): 97.11% (UV/VIS/NIR % abosorptance) 92.12 (% IR emittance)
Hybrid organic-inorganic sol-gel (5_G"): 97.56 % (UV/VIS/NIR % abosorptance) 92.03 (% IR emittance)
SolarBlack (for comparison - existing developed coating): 95.04 % (UV/VIS/NIR % abosorptance) 73.61 (% IR emittance)
It can be seen that the alternative formulations, both inorganic and hybrid, show better results than SolarBlack® and baseline “3_3” formulation.
Exploitation:
Work conducted will be report at the next scheduled European Conference on Spacecraft Structures Materials and Environmental Testing in Toulouse, France. Further development will be carried out and prototypes tested with the European Space Agency space research and technology centre (ESTEC).
From an optical perspective the developed prototype has achieved a comparable performance to the SoA for optical stray light suppression and a slightly lower performance for thermal emissivity. More work is required to increase the TRL level of the material to make it available be available to the European market for the next generation of earth observation and telecommunications satellites, with such platforms being increasingly necessary to monitor climate change and deliver communications services globally.