| Yield Properties of Tungsten and Tungsten Heavy Alloys |
JUN 93 |
13 pages |
| Authors:
Kenneth F. Ryan; Robert J. Dowding; ARMY RESEARCH LAB WATERTOWN MA
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 | This report describes the progress made in dynamic thermo-mechanical investigations, using the Gleeble 1500, of the yield properties of tungsten heavy alloys. This study describes properties of tungsten heavy alloy at elevated temperatures and strain rates, that can be useful in the modeling of long rod kinetic energy penetrator behavior.... Tungsten alloys, Compression, Annealing, Process control, Deformation, Strain rate, Mechanical properties |
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| Assessment of Chromate and Non-Chromate Conversion Coatings for Al Alloys Using Electrochemical Impedance Spectroscopy |
JUN 93 |
23 pages |
| Authors:
F. Chang; M. Levy; R. Huie; ARMY RESEARCH LAB WATERTOWN MA
|
| A study was conducted to evaluate whether a non-chromate conversion coating (Sanchem) for Al alloys (Al 2024 and 7075) could be a suitable replacement for the currently used chromate conversion coating (Alodine) without compromising corrosion resistance. Electrochemical impedance spectroscopy (EIS) and salt spray testing were employed to compare the corrosion behavior of coatings consisting of (a) pretreatment only (Sanchem or Alodine), (b) pretreatment (Sanchem or Alodine) plus primer (epoxy polyamide ... |
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| Modeling the Impact Behavior of AD85 Ceramic Under Multi-Axial Loading |
MAY 93 |
45 pages |
| Authors:
A. M. Rajendran; ARMY RESEARCH LAB WATERTOWN MA
|
| This report presents an advanced constitutive model to describe the complex behavior of ceramic materials under impact loading conditions. The governing equations utilize a set of microphysically based constitutive relationships to model deformation and damage processes in a ceramic. The total strain is decomposed into elastic, plastic, and microcracking components. The model parameters for AD85 ceramic were determined using the data from split Hopkinson bar (SHB) and bar-on-bar experiments under ... |
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| The Effect of Plasma Treatment on Interfacial Bond Characteristics of Kevlar/Epoxy Laminates as Measured by T-Peel Tests |
MAY 93 |
13 pages |
| Authors:
Rachel A. Michaud; Joey L. Mead; ARMY RESEARCH LAB WATERTOWN MA
|
| Composite materials are used in a wide variety of applications where their anisotropic properties allow the material to be tailored for each application. Unfortunately, aramid fiber composites may have limited applications due to poor transverse properties. These poor transverse properties are the result of weak interfacial bonding. Improvement of the interfacial bond strength has been an area of active research. Plasma treatment is one method that can be used to ... |
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| Army P/M Research and Development Overview |
MAY 93 |
23 pages |
| Authors:
Robert J. Dowding; Martin G. Wells; Andrew Crowson; ARMY RESEARCH LAB WATERTOWN MA
|
| The Army uses of powder metallurgy (P/M) extend from the conventional press and sinter to the more exotic processes of liquid phase sintering of tungsten heavy alloys (WHA) and powder injection molding (PIM). Many of the more advanced high performance applications require extensive research and development (R and D) prior to fielding of the application. Examples arc the intense research into WHA in the last ten years. This research has ... |
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| Effect of Powder Processing on Slip Casting Parameters and Sintering of Si3N4(-)Y2O3(-)SiO2 |
APR 93 |
16 pages |
| Authors:
Gary Gilde; George Gazza; ARMY RESEARCH LAB WATERTOWN MA
|
| A procedure was developed for slip casting Si3N4(-)Y2O3(-)SiO2 compositions. Thesilicon nitride was oxidized to supply the silica. The procedure resulted in 65 w/o slips with viscosities of 35 mPa(dot)s which, when cast, yielded compacts which were 56% of theoretical density. Slips with 70 w/o solids loading were also prepared having viscosities of 120 mPa(dot)s. The properties of the slips were influenced by the starting silicon nitride powder, dispersant, and milling ... |
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| Assessment of Projectile Shatter Using Digital Image Processing Techniques |
APR 93 |
25 pages |
| Authors:
James D. Kleinmeyer; ARMY RESEARCH LAB WATERTOWN MA
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| This report describes a novel technique for identifying the advent of projectile shatter in ballistically tested armor specimens. The methodology proposed is based on the use of digital image processing techniques for visually mapping out the interior of a ballistic cavity. Such a map may then be used to determine if projectile shatter has occurred and if so, to gain additional information on the approximate depth, location, and degree of ... |
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| Strain Concentration Assessment of Laminates Subjected to Low Velocity Impact |
APR 93 |
20 pages |
| Authors:
Robert F. Anastasi; Steven M. Serabian; ARMY RESEARCH LAB WATERTOWN MA
|
| Low velocity impact upon composite laminates can lead to both apparent and non-apparent damage zones that result in structural strain concentrations. The strain concentrations can be, or grow to be, larger than permissible design levels through static or cyclic loading conditions thus drastically reducing the structural integrity of the composite component. In this paper, glass/epoxy composite coupons in three laminate orientations were damaged by low velocity impact that create a ... |
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| Durability of Quick Reaction Satellite Antenna (QRSA) Trunnion Castings |
MAR 93 |
26 pages |
| Authors:
Wego Wang; Martin G. Wells; ARMY RESEARCH LAB WATERTOWN MA
|
| Repeated failures of quick reaction satellite antenna (QRSA) trunnion castings in the field caused alarming concerns about their durability. Arguments over the cause of the failures, ranging from improper installation, unbalanced and/or excess force to poor design and insufficient material strength, have been disputed between the contractor and the government engineers. Incipient melting during solution treatment was also suspected as one of the reasons responsible for cracking in the original ... |
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| Applications of Laser Light Scattering in Polymer Dilute Solution Characterization |
FEB 93 |
31 pages |
| Authors:
Marie K. Potts; ARMY RESEARCH LAB WATERTOWN MA
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| Dynamic light scattering (or photon correlation spectroscopy, PCS) can be used to determine the frequency distribution of the light scattered from polymer solutions. This distribution contains information about the dynamics of the system. Depending on the wavelength of radiation and the size of the polymer molecule, the translations and rotations of the entire molecule, or the motions of the monomers can be studied. This information, combined with static light scattering ... |
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| Oxidation and Hot Corrosion of Superalloys Rene 100 and X-40 at Temperatures of 1475 F to 2000 F |
FEB 93 |
25 pages |
| Authors:
M. Levy; J. J. Falco; F. Pettit; ARMY RESEARCH LAB WATERTOWN MA
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| The oxidation resistance and hot corrosion resistance of two superalloys, Rene 100 and X-40, and an aluminide coating for the protection of one of the superalloys are compared. The comparison is made by using tube- furnace oxidation and hot corrosion tests employing a Mettler TGA apparatus at temperatures of 1475 deg F to 2200 deg F. For hot corrosion tests the samples were precoated with Na2SO4 prior to heating to ... |
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| Tungsten Alloy Technology |
JAN 93 |
85 pages |
| Authors:
Robert J. Dowding; ARMY RESEARCH LAB WATERTOWN MA
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| The papers collected here represent contributions to the International Conference on Tungsten and its Alloys in which Materials Directorate personnel had primary or secondary authorship responsibility. The conference was held in Arlington, VA, 16-18 November 1992. These papers are indicative of the present interests of the Army in tungsten alloys for kinetic energy penetrator applications. The papers are compiled in alphabetical order, according to the last name of the first ... |
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| Observations and Evaluations of a Far East Trip |
DEC 92 |
18 pages |
| Authors:
Wego Wang; ARMY RESEARCH LAB WATERTOWN MA
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| To evaluate the technological capability of Far East countries, the author attended the first Pacific Rim International Conference on Advanced Materials and Processing in China, and visited Nippon Steel and several universities. China is an old country with a glorious history in technology. She recently re-established her diplomatic relationship with western countries. Attendance at this conference provided an opportunity to communicate with Chinese scientists and evaluate their capability and progress. ... |
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