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Initial Studies Of Gun Tube Erosion Macroscopic Surface Kinetics
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Book Synopsis Initial Studies of Gun Tube Erosion Macroscopic Surface Kinetics by :
Download or read book Initial Studies of Gun Tube Erosion Macroscopic Surface Kinetics written by and published by . This book was released on 2001 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current theories concerning gun tube erosion consider that erosion can occur under various conditions. The worst condition occurs when the melting temperature of the gun steel is exceeded for the tube's inner surface. This causes the tube to grossly melt This melt wipe mechanism is not as simple as once thought because the propellant product gases are known to read with the surface, resulting in an altered surface material. This altered material may have a lower melting temperature than that of the gun steel and/or weakened mechanical properties. Previous surface reaction studies by the authors used a generalized equilibrium scheme with a control volume analysis to represent surface reactions occurring during a cannon firing. This led to a postreaction treatment at the interface which incorporated the subsurface diffusion of species to limit the surface reaction. In this study, the surface reactions and rates are specified explicitly with published rates and guidance from fundamental molecular modeling results. The results demonstrate the utility of the surface reaction mechanism presently employed and the incorporation of finite rate surface kinetics in the fundamental physical representation of erosion.
Download or read book Ballistics 2011 written by Ernest Baker and published by DEStech Publications, Inc. This book was released on 2011-09 with total page 2230 pages. Available in PDF, EPUB and Kindle. Book excerpt: Includes papers that were first presented at a September 2011 conference organized by the National Defense Industrial Association and the International Ballistics Society. This title includes a CD-ROM that displays figures and illustrations in articles in full color along with a title screen and main menu screen.
Book Synopsis Gun Tube Surface Kinetics and Implications by : Paul J. Conroy
Download or read book Gun Tube Surface Kinetics and Implications written by Paul J. Conroy and published by . This book was released on 2001 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current theories concerning gun tube erosion consider that erosion can occur under various conditions. Propellant product gases are known to react with the surface resulting in an altered surface material which may melt or pyrolyze due to a lower melting temperature than that of the gun steel and or weakened mechanical properties. Previous surface reaction studies by the authors used a generalized equilibrium scheme with a control volume analysis to represent surface reactions occurring during a cannon firing. This led to a post reaction treatment at the interface which incorporated the subsurface diffusion of species to limit the surface reaction. In this study, the surface reactions and rates are specified explicitly with published rates and guidance from fundamental molecular modeling results. The results demonstrate the utility of the employed surface reaction mechanism as well as the incorporation of finite rate surface kinetics.
Book Synopsis Recent Advances in Aerospace Engineering by : Sanjay Singh
Download or read book Recent Advances in Aerospace Engineering written by Sanjay Singh and published by Springer Nature. This book was released on with total page 605 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis 120-mm Gun Tube Erosion Including Surface Chemistry Effects by :
Download or read book 120-mm Gun Tube Erosion Including Surface Chemistry Effects written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A theoretical model that addresses thermochemical erosion in gun tubes is presented. The model incorporates two interior ballistics codes-XKTC and IBHVG2-and the thermochemical code BLAKE to provide the necessary state variables and bulk species concentrations of the core flow as input. This erosion model utilizes a Crank-Nicolson integration scheme, with dynamic gridding capability to account for material ablation, as well as the addition of energy sources and heat transfer augmentation due to surface deviations. A mass transport scheme, utilizing the Lennard Jones 6-12 diffusion model, enables individual species to be transported to the surface from the core flow. Also fully coupled is a separate thermochemical routine which incorporates the NASA Lewis database. The code is written modularly, enabling the inclusion and modification of existing submodules. Erosion results comparing a fielded kinetic energy tank round and a candidate next generation tank round are presented. The thermochemical effects at the surface are also shown and discussed.
Book Synopsis First Principles Predictions of Gun Tube Erosion Chemistry and Possible Protective Coatings by :
Download or read book First Principles Predictions of Gun Tube Erosion Chemistry and Possible Protective Coatings written by and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Increasing the service lifetime of military machinery will improve logistics in the field (less down-time due to maintenance or replacement) and will free up resources for other pressing needs. To this end, the Army has a vested interest in enhancing the lifetime of gun barrels, which are limited currently by erosion of the steel from which the gun barrels are made. However, it is exceedingly difficult to determine experimentally in situ the mechanisms of erosion. Therefore, computer simulations can help elucidate those mechanisms and in ultimately extending the lifetime of gun barrels by discovering new ways to inhibit erosion.
Download or read book Erosion in Large Gun Barrels written by and published by . This book was released on 1975 with total page 57 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis First Principles and Multiscale Modeling of Spallation and Erosion of Gun Tubes by :
Download or read book First Principles and Multiscale Modeling of Spallation and Erosion of Gun Tubes written by and published by . This book was released on 2005 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: This represents the final report for two years of research at UCLA by the PI and her group on the gun tube erosion problem. In the past two years, they created new quantum-based simulation tools (both first principles and multiscale modeling techniques) and investigated surface, bulk, and interfacial materials aspects of the gun tube erosion problem. In brief, they developed: (i) two new versions of their spin-dependent pseudopotential theory that provides a more ab initio and more accurate description of magnetic transition metals such as Fe, (ii) a multiscale model that couples chemistry and mechanics to study hydrogen embrittlement in steel, and (iii) a scheme for calculating fracture energies of materials with mobile impurities (such as hydrogen in iron). They applied our spin-dependent pseudopotential theory to evaluate magnetism of vanadium surfaces, and applied density functional theory (DFT) to evaluate TiC and ZrC as possible protective coatings for steel. They also characterized via DFT the energetics and kinetics of how hydrogen and carbon adsorb and diffuse into iron, the structure and relative stability of cementite (iron carbide) surfaces, as well as predicting pathways for CO and H2S adsorption, diffusion, and dissociation on Fe surfaces.
Book Synopsis U.S. Army Research Laboratory Gun Tube Erosion Code (ATEC) User's Guide by : Paul J. Conroy
Download or read book U.S. Army Research Laboratory Gun Tube Erosion Code (ATEC) User's Guide written by Paul J. Conroy and published by . This book was released on 2003 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Physicochemical Aspects of Gun Barrel Erosion and Its Control by :
Download or read book Physicochemical Aspects of Gun Barrel Erosion and Its Control written by and published by . This book was released on 1975 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gun tube erosion can be defined as the bore surface damage and bore enlargement caused by firing, which can lead to loss in accuracy and the effectiveness of the weapon. It is one of the two major factors on the basis of which gun tubes are condemned; the other factor being fatigue life, Erosion is a complex phenomenon resulting from the interaction of propellant gases and the projectile with the surface of the bore. The bore surface is exposed for a short time to temperature approaching the melting point of steel, pressures as high as 50,000 psi, reactive atmosphere composed of CO, CO2, H2O, H2, N2, and numerous other identified and unidentified constituents. Superimposed on these conditions are the high velocity of gases and swaging action of the projectile rotating band. It is the objective of this presentation to review the physicochemical processes involved in erosion and indicate some critical areas which need further investigation. Also, various efforts to control erosion in barrels will be briefly discussed.
Book Synopsis Erosion in Large Gun Barrels by : NATIONAL MATERIALS ADVISORY BOARD (NAS-NAE) WASHINGTON D C.
Download or read book Erosion in Large Gun Barrels written by NATIONAL MATERIALS ADVISORY BOARD (NAS-NAE) WASHINGTON D C. and published by . This book was released on 1975 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: The erosion of gun tubes is a very complex interdisciplinary problem involving several branches of engineering and science. Several mechanisms are responsible for this limitation to gun tube life, some of which are of thermal origin, some are mechanical and some chemical. The exact combination of these mechanisms will depend upon the following components of the gun system. (1) The gun barrel system; (2) The projectile system; (3) The charge assembly; (4) Wear reducing additives in the propellant; (5) Firing conditions. After reviewing the history of gun barrel erosion from these several points of view, possible mechanisms are discussed. Several other fields of engineering endeavors that are limited by severe wear problems are reviewed for possible sources of technology transfer. The report concludes by suggesting long and short range programs, including a number of specific ideas that should be evaluated.
Book Synopsis Gas Chemistry Effects on Gun Barrel Erosion. A Shock Tube Gun Investigation by :
Download or read book Gas Chemistry Effects on Gun Barrel Erosion. A Shock Tube Gun Investigation written by and published by . This book was released on 1982 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: The subject program is part of a continuing effort to identify distinct mechanisms that contribute to gun barrel wear and erosion. The thermochemical effects of altering the CO/CO2 ratio of a propellant gas in a gun tube was the main topic for investigation in this program. Experiments were conducted in the Shock Tube Gun (STG), a ballistic compressor, designed and developed by Calspan Corporation. This facility can compress mixtures of pure gases to simulate propellant gas flow conditions and cycle times experienced in large caliber guns. Tests were conducted with mixture ratios of carbon monoxide and carbon dioxide that characterize the normal range of CO/CO2 ratios found in propellant gas, i.e., 2.0 to 8.1. Progressive substitution of carbon monoxide for nitrogen in the mix quantified erosion as a function of increasing Co concentration or CO/CO2 ratio. Subsequent tests were conducted with gas mixtures containing double the amount of carbon monoxide and carbon dioxide but with the same effect CO/CO2 ratio, to measure erosion as a function of absolute reactant concentration for the two gas species. The basic chemical effect was observed to be a shift in the erosion threshold to less severe convective heating conditions in response to increasing the CO/CO2 ratio above a value of 5.6. The magnitude of the shift appeared to be directly proportional to the absolute concentrations of the two reactant gases. Variation of both CO/CO2 ratio and absolute amounts of the two gases resulted in distinct changes in specimen surface characteristics, both at near threshold and above threshold flow conditions.
Book Synopsis Shock Tube Gun Melting Erosion Study by : Franklin A. Vassallo
Download or read book Shock Tube Gun Melting Erosion Study written by Franklin A. Vassallo and published by . This book was released on 1979 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat transfer, melting, and erosion tests were conducted using a unique Shock Tube Gun Facility available at Calspan. Materials of interest were subjected to intense heating using non-reactive gas mixtures. Pure melting of materials was obtained at heating conditions representing those of actual guns. A computer code was formulated, written, tested, and shown to adequately normalize the gross thermal data, thus permitting determination of expected bore temperatures and/or material loss for given heating conditions. It was found that, although the bore surface temperature of steels tested in the non-reactive gases of the Shock Tube Gun achieved temperatures of the same magnitude as those in large caliber guns where bore surface cracking is produced, no similar surface cracking of steels was observed. It is concluded that chemical activity of gun gases is partially responsible for crack initiation in gun tubes. (Author).
Book Synopsis Gray Layers and the Erosion of Chromium Plated Gun Bore Surfaces by :
Download or read book Gray Layers and the Erosion of Chromium Plated Gun Bore Surfaces written by and published by . This book was released on 1999 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present report describes observations and analyses in a survey study of erosion damage in chromium plated gun bore surfaces. Sections of three fired chromium plated 120-mm M256 gun tubes and two 155-mm gun tubes (M199 and XM297) were examined by optical microscopy, laser scanning confocal microscopy (LSCM), and electron microprobe analyses. These tubes experienced significant erosion damage and chromium loss. A rifled portion of the 155-mm M199 tube was plated with low contractile (LC) chromium and the 155-mm XM297 and 120-mm M256 tubes were plated with high contractile (HC) chromium. New insights regarding the erosion process and the origin of chromium loss are obtained by investigation of the initial damage to the steel at the tips of the fine cracks in the chromium. Reaction products from gas-metal interactions at the gun bore surface are normally difficult to find because of gas wash effects. Examination of unetched specimens from a variety of fired tubes shows that these products remain in lace in the relatively protected regions beneath the chromium when chromium crack widths are small. The initial damage is manifested as gray layers or gray regions in the steel at the tips of the fine chromium cracks. Electron microprobe analyses indicate that these gray layers are composed of iron sulfide, iron oxide, or mixtures of the two compounds.
Book Synopsis Physics of Surfaces and Interfaces by : Harald Ibach
Download or read book Physics of Surfaces and Interfaces written by Harald Ibach and published by Springer Science & Business Media. This book was released on 2006-11-18 with total page 653 pages. Available in PDF, EPUB and Kindle. Book excerpt: This graduate-level textbook covers the major developments in surface sciences of recent decades, from experimental tricks and basic techniques to the latest experimental methods and theoretical understanding. It is unique in its attempt to treat the physics of surfaces, thin films and interfaces, surface chemistry, thermodynamics, statistical physics and the physics of the solid/electrolyte interface in an integral manner, rather than in separate compartments. It is designed as a handbook for the researcher as well as a study-text for graduate students. Written explanations are supported by 350 graphs and illustrations.
Book Synopsis Evangelisches Gemeindezentrum Freiburg-Landwasser by : Günter Kranz
Download or read book Evangelisches Gemeindezentrum Freiburg-Landwasser written by Günter Kranz and published by . This book was released on 1972 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1979 with total page 770 pages. Available in PDF, EPUB and Kindle. Book excerpt:
