The Atomic Oxygen Erosion Resistance Effect and Mechanism of the Perhydropolysilazane-Derived SiOx Coating Used on Polymeric Materials in Space Environment

Abstract

In this work, the atomic oxygen (AO) erosion-resistance effect and mechanism of the Perhydropolysilazane (PHPS) coating were investigated from the perspective of element distribution in the depth direction. The results revealed that the coating demonstrated good adhesion and intrinsic AO erosion-resistance, which was attributed to the composition gradient formed in the coating. Moreover, the oxygen ratio of the SiOx on top layer of the coating could be elevated during AO exposure, strengthening the Ar ion etching durability of the coating. According to these results, an AO erosion-resistance mechanism model of the PHPS-derived SiOx coating was finally obtained.

Pollution Effects and Management of Orbital Space Debris

“…11 In addition to composite shielding, polyethylene shielding, and the Whipple shield, there are three main types of organic polymeric coatings that could be applied to minimize the amount of erosion taking place on the satellite's surface as much as possible, including polysiloxane polymers, polysilazane polymers, and fluorinated polymers. 54 Out of these three, the top ranked protective coating is the polysiloxane polymer coating, as it has high resistivity and binds to a remarkably high degree. 54 Other inorganic coatings include SiO 2 and Al 2 O 3 , which are also known for their poor adhesive properties.…”

“…54 Perhydropolysilazane-derived SiOx (PHPS) coating, as founded by Qi et al, is a gradient coating that enforces gradient structure and composition by reacting with a moist and cold environment to harden as a top-isolating coating on the body of a spacecraft, which provides a high level of protection against atomic oxygen for 48 years. 54 It is essential to note that existing mitigation measures have been already applied to ensure repairing, refueling, or upgrading the already existing spacecrafts in situ, and only limited ADR target defunct satellites but do not actually deal with the remaining present debris. It is noted that deorbiting takes place by directing the target objects either toward graveyard orbits or toward earth for a controlled or uncontrolled atmospheric incineration.…”

“… 54 Out of these three, the top ranked protective coating is the polysiloxane polymer coating, as it has high resistivity and binds to a remarkably high degree. 54 Other inorganic coatings include SiO 2 and Al 2 O 3 , which are also known for their poor adhesive properties. 54 Perhydropolysilazane-derived SiOx (PHPS) coating, as founded by Qi et al, is a gradient coating that enforces gradient structure and composition by reacting with a moist and cold environment to harden as a top-isolating coating on the body of a spacecraft, which provides a high level of protection against atomic oxygen for 48 years.…”

A Reactive Molecular Dynamics Study on Crosslinked Epoxy Resin Decomposition under High Electric Field and Thermal Aging Conditions

“…Previous studies have successfully employed reactive molecular dynamics (MD) simulations on reaction rates, species products, and initiation time of polymer decomposition and organic compound combustion at high-pressure and -temperature conditions with an extremely strong electrostatic field that cannot be characterized by high-voltage experiments such as dielectric breakdown and partial discharge for polymeric insulation materials [ 21 , 22 , 23 ]. Reactive MD simulations have revealed the intrinsic mechanism and chemical reaction path of small molecule products such as water and hydrogen, and proved that the thermal decomposition of EP polymers is initiated by breaking oxygen bridge bonds adjoining to benzene rings [ 24 , 25 , 26 , 27 ]. Synergetic electro-thermal decomposition of carbon nanotube/epoxy composites was revealed by reactive MD simulations, and the unsealed carbon nanotubes were found to be effective in improving the thermal stability by inhibiting molecular-chain thermal motions in EP polymers [ 25 ].…”

“…MD simulations adopting ReaxFF can also be implemented to evaluate the impacting damages of atomic oxygen bombardments by calculating mass loss, molecular product, transient temperature, and surface penetration depth [ 26 ]. ReaxFF is also capable of simulating erosion-resistant characteristics of spacecraft polymeric materials under impacts of high-velocity ions [ 27 ]. Therefore, ReaxFF should be capable of simulating the electro-thermal decomposition of crosslinked EP polymers under electrical impacts of active ions that are generated by surface electrical creepage discharge or electrical partial discharge.…”