E. N. Voronina

Radiation effects on spacecraft materials

Radiation conditions are described for various space regions, radiation-induced effects in spacecraft materials and equipment components are considered and information on theoretical, computational, and experimental methods for studying radiation effects are presented. The peculiarities of radiation effects on nanostructures and some problems related to modeling and radiation testing of such structures are considered.

Multi-step reactions mechanism for F atoms interactions with organosilicate glass and SiOx films

An ab initio approach with the density functional theory (DFT) method was used to study F atom interactions with organosilicate glass (OSG)-based low-k dielectric films. Because of the complexity and significant modifications of the OSG surface structure during the interaction with radicals and etching, a variety of reactions between the surface groups and thermal F atoms can happen. For OSG film etching and damage, we propose a multi-step mechanism based on DFT static and dynamic simulations, which is consistent with the previously reported experimental observations. The important part of the proposed mechanism is the formation of pentavalent Si atoms on the OSG surface due to a quasi-chemisorption of the incident F atoms. The revealed mechanism of F atom incorporation into the OSG matrix explains the experimentally observed phenomena of fast fluorination without significant modification of the chemical structure. We demonstrate that the pentavalent Si states induce the weakening of adjacent Si–O bonds and their breaking under F atom flux. The calculated results allow us to propose a set of elementary chemical reactions of successive removal of CH3 and CH2 groups and fluorinated SiO x matrix etching.

Mathematical and experimental simulation of impact of atomic oxygen of the Earth’s upper atmosphere on nanostructures and polymer composites

The article discusses the results of mathematical and experimental simulation of the impact of atomic oxygen of the Earth’s upper atmosphere on carbon and boron nitride nanotubes, graphene, hexagonal boron nitride sheets, and graphene nanoribbons, as well as composites based on polymer matrices with fillers in the form of nanosized particles of various types.

Effect of porosity and pore size on dielectric constant of organosilicate based low-k films : an analytical approach

An analytical approach allowing to analyze effect of porosity, pore size, and interconnectivity on dielectric constant of organosilicate based low-k materials is developed. Within the framework of this approach, a good agreement between the calculated and experimentally measured dielectric constants for several porogen (template) based organosilicate glasses low-k films is demonstrated. It is shown that the best agreement between the calculated and measured k-values corresponds to low-k structure with CH3 groups localized on pore wall surface. The results also demonstrate a good agreement with recently published results of similar analysis based on numerical approach.

Atomic Oxygen Influence on Polymer Nanocomposites with Different Fillers

This paper describes results of ground-based simulation of atomic oxygen influence on samples of polymer composites with different fillers. Polyimide and polyamide-imide were used as matrices, and polyorganosiloxanes, inorganic nanoparticles of Al2O3, TiO2, WC, multiwalled carbon nanotubes, and detonation nanodiamonds were used as fillers. Data on mass loss of composite samples due to atomic oxygen exposure and results of surface morphology analysis are given.

Ab initio study of unzipping processes in carbon and boron nitride nanotubes under atomic oxygen impact

We apply first principles calculations to compare the carbon and boron nitride nanotube unzipping under atomic oxygen impact. We show that the attack of several oxygen atoms can cause bond breaking in nanotubes, but the structure of boron nitride nanotubes is less damaged than the structure of carbon ones. With increasing diameter, the structural damage of nanotubes reduces.

Use of hyperbranched polyethoxysiloxane to improve the resistance of thermoplastic polyimide coatings to atomic oxygen environment

Polyimide thin films both unmodified and modified with hyperbranched polyethoxysiloxane were treated with accelerated oxygen plasma flow to imitate a low Earth orbit environment. The resulting changes in the surface morphology were studied using scanning electron microscopy. The erosion yield values were calculated and the relative stability of the tested samples was established. It was shown that the polyimide-polyethoxysiloxane composites have higher atomic oxygen resistance owing to, presumably, the siloxane particles dispersed uniformly in the polyimide matrix. The study found that all plasma-treated samples exhibit the same fibrous, carpet-like surface morphology with some minor variations caused by differences in the chemical composition of polymers.

Multiscale simulation of polymer nanocomposites

Existing methods for a multiscale simulation of polymer nanocomposites, which are presently thought to be among the most promising materials for applications in various realms of science and technologies, are considered. Factors that affect the structure and properties of polymer nanocomposites are analyzed. These factors include the properties of nanoobjects used as fillers, special features of the interaction between a nanofiller and a host material, and the uniformity of the nanofiller distribution over the polymer volume. It is shown that specific simulation methods are required for properly taking into account each such factor, and an optimum scheme is chosen for a multiscale simulation of polymer nanocomposites. Some results of the calculations performed on the basis of the approach described in this article are presented.

Space Model—A New Russian Handbook on Spacecraft/Environment Interaction

In 2007 the scientists at Skobeltsyn Institute of Nuclear Physics Moscow State University in close cooperation with experts from many space industry organizations, institutes of Russian Academy of Science and universities prepared and published a two‐volume scientific handbook Space Model. Nearly 180 authors from 50 different organizations have taken part in creating the Space Model handbook. The total volume of the handbook amounts to more than 2000 pages.In the 1st volume the physical conditions in the outer space are described, some computational models are considered, various reference data for computing are presented. The 2nd volume is devoted to the analysis of the space environment effects on spacecraft materials and subsystems, and of ground‐based and space testing methods. The influence of spacecraft and rocket on the near‐Earth space is also discussed.The handbook is intended for specialists of space industry and students. The paper deals with the content of the handbook and the possibilities of...

Erosion of carbon nanotube-based polymer nanocomposites exposed to oxygen plasma

We present the results of the simulation tests of samples of polymer nanocomposites based on carbon nanotubes for resistance to oxygen plasma in the Earth’s upper atmosphere. Data on the weight loss of the samples, the results of analysis of their surface structure after irradiation, and data on arrays of carbon nanotubes damaged under the effect of oxygen plasma are given. Possible mechanisms of destruction of the nanotubes are discussed.