Download or read book Laboratory Investigation of Atomic Oxygen Metal Surface Interactions written by Gary Walfred Sjolander and published by . This book was released on 1975 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multiscale Atomistic Simulation of Metal oxygen Surface Interactions written by and published by . This book was released on 2007 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our long-term vision is for a comprehensive and fundamental understanding of a critical gas-surface reaction, nano-oxidation from the adsorption of oxygen atoms on the metal surface to the coalescence of the bulk oxide via coordinated multi-scale theoretical and in situ experimental efforts. Reaching this goal necessitates close collaborations between theorists and experimentalists, and the development and utilization of unique and substantial theoretical and experimental tools. Achievement of this goal will be a major breakthrough in dynamic surface/interface reactions that will dramatically impact several scientific fields. Many of these are of interest to DOE, such as thin films and nanostructures that use oxidation for processing, heteroepitaxy, oxidation and corrosion, environmental stability of nano-devices, catalysis, fuel cells and sensors. The purpose of this specific DOE program was the support for the theoretical effort. Our focus for the first round of funding has been the development of a Kinetic Monte Carlo (KMC) code to simulate the complexities of oxygen interactions with a metal surface. Our primary deliverable is a user-friendly, general and quite versatile KMC program, called Thin Film Oxidation (TFOx). TFOx-2D presently simulates the general behavior of irreversible 2-dimensional nucleation and growth of epitaxial islands on a square or rectangular lattice. The TFOx model explicitly considers a very large range of elementary steps, including deposition, adsorption, dissociation of gas molecules (such as O2), surface diffusion, aggregation, desorption and substrate-mediated indirect interactions between static adatoms. This capability allows for the description of the numerous physical processes involved in nucleation and growth. The large number of possible input parameters used in this program provides a rich environment for the simulation of epitaxial growth or oxidation of thin films. As a first demonstration of the power of TFOx-2D, the input parameters were systematically altered to observe how various physical processes impact morphologies. It was noted that potential gradients, developed to simulate medium-range substrate mediated interactions such as strain, and the probability of an adatom attaching to an island, have the largest effect on island morphologies. Nanorods, and round, square and dendritic shapes have all been observed which correlate well with experimental observations of the wide range of oxide morphologies produced during in situ oxidation of Cu thin films. To allow TFOx to be accessible to the rest of the scientific community, a web-site describing TFOx has been developed: www.tfox.org. Brief highlights of our progress to date are summarized as: Development of TFOx-2D, a versatile kinetic Monte Carlo code that can simulate atomistic transport, nucleation and growth, and includes potential gradients to simulate medium-range substrate mediated effects (e.g., strain); Systematic study of TFOx-2D input parameters to reveal a variety of nano-structures that resemble those seen experimentally; Parallelization of the Streitz-Mintmire potential and Rappe-Goddard approach for determining dynamic charge transfer at a metal-oxide interface, which is the critical step required for molecular dynamic simulations of oxygen-metal interactions; Benchmark calculations of Cu and Cu2O physical properties to determine the most accurate electronic structure approach; and, Demonstration of the greater universality of the Tersoff-Tromp elastic strain relief model of nano-rod formation to a gas-surface reaction. Hence, we have established the ground work for a truly comprehensive and multi-scale theoretical tool that can simulate any gas-surface reaction, including oxidation, from the atomic level to the mesoscale, from first principles. The direct comparison between these simulations and in situ experiments of metal nano-oxidation will lead to new knowledge of this important surface reaction.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Download or read book Atomic Oxygen Interaction with Spacecraft Materials Relationship Between Orbital and Ground based Testing for Materials Certification written by Jon B. Cross and published by . This book was released on 1991 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Atomic Oxygen Durability Evaluation of Protected Polymers Using Thermal Energy Plasma Systems written by and published by . This book was released on 1995 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Technology for Large Space Systems written by and published by . This book was released on 1990 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government Reports Announcements written by and published by . This book was released on 1974 with total page 1000 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book First principles Studies of the Reactivity of Oxygen on Transition Metal Surfaces written by Ye Xu and published by . This book was released on 2004 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1995 with total page 1208 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Determination of Ground Laboratory to In Space Effective Atomic Oxygen Fluence for DC 93 500 Silicone written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-24 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this research was to calibrate the ground-to-space effective atomic oxygen fluence for DC 93-500 silicone in a thermal energy electron cyclotron resonance (ECR) oxygen plasma facility. Silicones, commonly used spacecraft materials, do not chemically erode with atomic oxygen attack like other organic materials but form an oxidized hardened silicate surface layer. Therefore, the effective atomic oxygen fluence in a ground test facility should not be determined based on mass loss measurements, as they are with organic polymers. A technique has been developed at the Glenn Research Center to determine the equivalent amount of atomic oxygen exposure in an ECR ground test facility to produce the same degree of atomic oxygen damage as in space. The approach used was to compare changes in the surface hardness of ground test (ECR) exposed DC 93-500 silicone with DC 93-500 exposed to low Earth orbit (LEO) atomic oxygen as part of a shuttle flight experiment. The ground to in-space effective atomic oxygen fluence correlation was determined based on the fluence in the ECR source that produced the same hardness for the fluence in-space. Nanomechanical hardness versus contact depth measurements were obtained for five ECR exposed DC 93-500 samples (ECR exposed for 18 to 40 hrs, corresponding to Kapton effective fluences of 4.2 x 10(exp 20) to 9.4 x 10(exp 20) atoms/sq cm, respectively) and for space exposed DC 93-500 from the Evaluation of Oxygen Interactions with Materials III (EOIM III) shuttle flight experiment, exposed to LEO atomic oxygen for 2.3 x 10(exp 20) atoms/sq cm. Pristine controls were also evaluated. A ground-to-space correlation value was determined based on correlation values for four contact depths (150, 200, 250, and 300 nm), which represent the near surface depth data. The results indicate that the Kapton effective atomic oxygen fluence in the ECR facility needs to be 2.64 times higher than in LEO to replicate equivalent exposure damage in the g

Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1967-05 with total page 1038 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Air Force Research Resum s written by and published by . This book was released on 1964 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Large Space Structures Systems in the Space Station Era written by and published by . This book was released on 1991 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Space Station Systems written by and published by . This book was released on 1986 with total page 606 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fourth Annual Workshop on Space Operations Applications and Research SOAR 90 written by and published by . This book was released on 1991 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government Reports Announcements Index written by and published by . This book was released on 1991-10 with total page 824 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book ERDA Energy Research Abstracts written by United States. Energy Research and Development Administration and published by . This book was released on 1976 with total page 988 pages. Available in PDF, EPUB and Kindle. Book excerpt: