Energy Dependence of Hyperthermal Oxygen Atom Erosion of a Fluorocarbon Polymer: Relevance to Space Environmental Effects

Abstract

The origin of the inconsistency in the erosion phenomena of fluorocarbon polymers between a ground-based atomic-oxygen test environment and the low Earth orbital space environment has been investigated. A detailed experiment was performed in order to study the effect of the high-energy component in the atomic-oxygen beam pulses on the erosion. The experiment was carried out with the combination of a polymer-coated quartz crystal microbalance and a high-speed chopper wheel installed in a laser-detonation atomic-oxygen facility. It was clearly observed that the mass-loss rates of both polyimide and fluorocarbon polymers depend on the impact energy of atomic oxygen. However, the energy dependence is more significant on the fluorocarbon polymer compared with that on polyimide. Collisions of atomic oxygen with translational energies higher than ∼5 eV induce a significant mass loss on the fluorocarbon polymer. These experimental findings agree with earlier measurements of the volatile products released during hyperthermal O-atom bombardment, and they are consistent with theoretical calculations on related systems. It is concluded that the difference in the collision energy distribution of atomic oxygen between laboratory and space environments is the major reason for the difference in erosion yields measured in the two environments.

Evolution of surface chemistry and morphology of hyperbranched polysiloxane polyimides in simulated atomic oxygen environment

“…However, the presence of AO in LEO makes a considerable threat to polyimides, which can cause significant reduction in physical, mechanical and optical properties of polyimides due to its ultra-strong oxidability [3][4][5]. As is reported, polyimide coated with TiO 2 or SiO 2 has exhibited superior AO resistance than unprotected one [3,16].…”

“…LEO is an orbit that extends from the earth's surface at sea level to an altitude of about 200-700 km [1,2], and most of it lies within the earth's atmosphere, where plenty of space environmental hazards, such as atomic oxygen (AO), thermal cycle, space radiation, high vacuum, ultraviolet (UV) and vacuum-ultraviolet (VUV) radiation, micro meteor, and space debris are present [1][2][3][4][5]. As a consequence, most organic materials onboard spacecrafts and artificial satellites may be rapidly eroded away due to the damage created by those aggressive environmental factors in LEO, especially the AO [5,6]. In LEO, AO may collide with spacecraft surfaces at a high relative velocity of approximately 7-8 km/s, which imparts the equivalent of 4.5-6 eV of translational energy (TE) to AO, thereby causing erosion called AO attack [7][8][9].…”

“…Polyimides, in particular aromatic polyimides like Kapton ® H, are extensively used onboard spacecrafts mainly as surface protective materials and lightweight flexible substrates in solar cells, owing to its inherent strong mechanical strength, high-temperature stability and desirable dielectric properties [3][4][5][9][10][11][12][13][14][15]. However, the presence of AO in LEO makes a considerable threat to polyimides, which can cause significant reduction in physical, mechanical and optical properties of polyimides due to its ultra-strong oxidability [3][4][5].…”

Sensitivity of rarefied gas simulations of ground tests to gas surface models

“…We consider the specific example of atomic oxygen erosion. Measurements 3 show that there is an energy-dependence of atomic oxygen erosion rates, and we 3. Through combining materials response characteristics with the rarefied gas dynamics modeling of space and chamber flows, we will elucidate some aspects of the relationship between the ground tests and on-orbit tests.…”

“…Tagawa et al 3 measured an energy dependence in the erosion of certain polymers by atomic oxygen. This energy dependence suggests that erosion rate measurements and materials lifetime predictions will in general benefit from knowing the energy spectrum of the atomic oxygen impinging upon the sample.…”