Electrochemical surface technologies for space applications 

Components for space applications require some special properties: In addition to an extremely low weight, these also include extraordinary reliability over a longer period of time. In addition to the substrate material, the surface also plays an extremely important role. In this lecture, three examples of electrochemical surface technology for space applications will be discussed.

Carbon fiber reinforced plastic (CFRP) is an extremely lightweight material (composite) with very good mechanical properties, such as high stiffness. With an additional metallic surface, they can be used as antennae for satellites or optical lightweight mirrors. However, due to the large and rapid temperature fluctuations in space as well as the different coefficients of thermal expansion (CTE), the deposition of well adherent metallic coatings on CFRP is a great challenge.

Additively manufactured components allow an optimal design and thus weight savings. If polymers are used as the material instead of metal, the weight saving is even greater. However, there are some disadvantages with plastics: they generally do not have the strength of metals, they are electrically non-conductive and can therefore become electrically charged. Furthermore, they outgas in a vacuum which can be a problem for other devices such as optical mirrors. Galvanically deposited metal layers can eliminate these disadvantages.

A large number of components for space applications require extremely low-friction surfaces, for example reaction wheels for changing or stabilizing the position of satellites, or hinges for unfolding antennae or photovoltaic systems. Liquid lubricants are not permitted in a vacuum because of the risk of evaporation, and solid lubricants normally have no storage potential for relubrication. Metallic composites with integrated solid lubricants such as microencapsulated MoS2 will reduce the CoF.