| Equivalent Crack Size Modelling of Corrosion Pitting in an AA7050-T7451 Aluminium Alloy and its Implications for Aircraft Structural Integrity |
Sep 2012 |
91 pages |
| Authors:
Bruce R Crawford; R K Sharp; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION VICTORIA (AUSTRALIA) AIR VEHICLES DIV
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 | Ageing military aircraft fleets are becoming the norm as fleet managers try to extend operational life without compromising safety. This has led to substantial world-wide research into ageing aircraft and the implications of corrosion and multi-site damage on aircraft residual strength and fatigue life. This report details part of DSTO's research program into the effect of pitting corrosion on aircraft structural integrity. The report focuses on F/A-18 structural aluminium alloy ... |
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| Fatigue Crack Initiation from Pitting Introduced during the Anodising Process |
Aug 2012 |
29 pages |
| Authors:
Cathy Smith; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION VICTORIA (AUSTRALIA) AIR VEHICLES DIV
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| This report discusses four examples of Australian Defence Force aircraft components manufactured from aluminium alloys that exhibited surface pitting arising from the anodising process. In three of the examples, the anodising pits acted as initiation sites for fatigue cracks, which ultimately led to failure of the components. The information presented in this report highlights the issue of anodising pitting and the associated potential for fatigue cracking which can extend to ... |
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| Explosives Dissolved from Unexploded Ordnance |
Oct 2011 |
104 pages |
| Authors:
Susan Taylor; Susan Bigl; Carrie Vuyovich; Jeanne Roningen; Anna Wagner; Nancy Perron; Steven Daly; Marianne Walsh; James Hug; COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH
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| For this work we: 1) sampled soil below unexploded ordnance (UXO) found in situ and noted the conditions of the rounds, 2) conducted laboratory tests to help us estimate high explosive (HE) dissolution from different sized holes in corroded rounds, and 3) used the modeling program Hydrus-1D and weather records to predict the ownward movement of the explosives into the soil. Although most of these UXO looked highly corroded, our ... |
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| Microbiologically Influenced Corrosion |
Jan-2009 |
39 pages |
| Authors:
Brenda J Little; Jason S Lee; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
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| The term microbiologically influenced corrosion (MIC) is used to designate corrosion due to the presence and activities of microorganisms, i.e., those organisms that cannot be seen individually with the unaided human eye, including microalgae, archaea, bacteria, and fungi. Microorganisms can accelerate rates or partial reactions in corrosion processes or shift the mechanism for corrosion. Microorganisms can influence pitting, dealloying, enhanced erosion corrosion, enhanced galvanic corrosion, stress corrosion cracking, and hydrogen ... |
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| Assessment of the Effect of Pitting Corrosion on the Safe Life Prediction of the P-3C |
DEC 2007 |
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| Authors:
Alexandra Shekhter; Christopher Loader; Weiping Hu; Bruce R. Crawford; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION VICTORIA (AUSTRALIA) AIR VEHICLES DIV
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 | This report presents the results of an experimental programme aimed at assessing the implications of pitting corrosion damage on P-3C safe lives calculated using the methods developed in the P-3C Service Life Assessment Program, the Equivalent Crack Size method and the Crack Initiation method. The results of both of these methods were that, for the pitting corrosion distribution used, the safe life prediction was not invalidated by corrosion. However, larger ... |
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| Observation and Study of Dislocation Etch Pits in Molecular Beam Epitaxy Grown Gallium Nitride With the Use of Phosphoric Acid and Molten Potassium Hydroxide |
JUN 2007 |
18 pages |
| Authors:
Fred Semendy; Unchul Lee; ARMY RESEARCH LAB ADELPHI MD
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| Defects continue to challenge the functionality and reliability gallium nitride (GaN)-based devices. GaN grown on sapphire by molecular beam epitaxy was investigated by wet etching in hot phosphoric acid (H3PO4) and molten potassium hydroxide (KOH). Hexagonally shaped etch pits were formed on the etched sample surfaces. Etched samples were characterized with the use of atomic force microscopy (AFM) and scanning electron microscopy (SEM) and SEM cathode luminescence (SEM-CL). AFM images ... |
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| Overview of Low Plasticity Burnishing for Mitigation of Fatigue Damage Mechanisms |
SEP 2005 |
7 pages |
| Authors:
Paul S. Prevey; N. Jayaraman; John Cammett; LAMBDA RESEARCH CINCINNATI OH
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| Surface enhancement technologies such as shot peening (SP), laser shock peening (LSP), and low plasticity burnishing (LPB) can provide substantial fatigue life improvement. However, to be effective, the compressive residual stresses that increase fatigue strength must be retained in service. LPB provides thermally stable compression and can be performed in conventional machine shop environments on CNC machine tools. LPB enables the extension of component service lives fatigue limited by various ... |
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| History of Sulphur Content Effects on the Thermal Stability of RP-1 under Heated Conditions |
14 JUL 2004 |
13 pages |
| Authors:
Solveig A. Irvine; Amanda K. Schoettmer; Ronald W. Bates; Michael L. Meyer; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| As technologies advance in the aerospace industry, a strong desire has emerged to design more efficient, longer life, reusable liquid hydrocarbon fueled rocket engines. To achieve this goal, a more complete understanding of the thermal stability and chemical makeup of the hydrocarbon propellant is needed. Since the main fuel used in modern liquid hydrocarbon systems is RP-1, there is concern that Standard Grade RP-1 may not be a suitable propellant ... |
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| Investigation of Gear and Bearing Fatigue Damage Using Debris Particle Distributions |
MAY 2004 |
16 pages |
| Authors:
Paula J. Dempsey; David G. Lewicki; Harry J. Decker; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
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| A diagnostic tool was developed for detecting fatigue damage to spur gears, spiral bevel gears, and rolling element bearings. This diagnostic tool was developed and evaluated experimentally by collecting oil debris data from fatigue tests performed in the NASA Glenn Spur Gear Fatigue Rig, Spiral Bevel Gear Test Facility, and the 500 hp Helicopter Transmission Test Stand. During each test, data from an on-line, in-line, inductance type oil debris sensor ... |
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| Factors Affecting Chrome Loss in Gun Tubes |
DEC 2003 |
22 pages |
| Authors:
Paul J. Cote; Mark E. Todaro; Mark Witherell; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
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| The objective of the study was to gain further insights into the origin of chromium loss in tank guns. The present report summarizes the results of a study surveying chromium loss at various critical locations along a 120-mm M256 tank gun tube. Tube no. 6824 was selected because it had fired relatively few rounds (119), while still exhibiting initiation of all the typical chromium damage features in the chamber and ... |
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| Investigation of the Effect of Corrosion Pitting on Fatigue Life of Aluminum Structure |
OCT 2003 |
141 pages |
| Authors:
Eric J. Tuegel; AIR FORCE RESEARCH LAB WRIGHT-PATTERSONAFB OH ANALYTICAL STRUCTURAL MECHANICS BRANCH
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| This report presents the results of testing to obtain data on the effect of pitting corrosion on the fatigue life of aluminum specimens. Forty-one coupons of 7075-T6 that had previously been exposed at various USAF bases around the world for up to a year were fatigue tested. The amount of corrosion on each had been previously characterized in terms of mass lost per unit of surface area. Additional characterization of ... |
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| Increased Surface Fatigue Lives of Spur Gears by Application of a Coating |
AUG 2003 |
14 pages |
| Authors:
Timothy L. Krantz; Clark V. Cooper; Dennis P. Townsend; Bruce D. Hansen; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CENTER
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| Hard coatings have potential for increasing gear surface fatigue lives. Experiments were conducted using gears both with and without a metal- containing, carbon-based coating. The gears were case-carburized AISI 9310 steel spur gears. Some gears were provided with the coating by magnetron sputtering. Lives were evaluated by accelerated life tests. For uncoated gears, all of fifteen tests resulted in fatigue failure before completing 275 million revolutions. For coated gears, eleven ... |
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| Spiral Bevel Gear Damage Detection Using Decision Fusion Analysis |
AUG 2002 |
12 pages |
| Authors:
Paula J. Dempsey; Robert F. Handschuh; Abdollah A. Afjeh; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
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| A diagnostic tool for detecting damage to spiral bevel gears was developed. Two different monitoring technologies, oil debris analysis and vibration, were integrated using data fusion into a health monitoring system for detecting surface fatigue pitting damage on gears. This integrated system showed improved detection and decision-making capabilities as compared to using individual monitoring technologies. This diagnostic tool was evaluated by collecting vibration and oil debris data from fatigue tests ... |
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| The Incorporation of Pitting Corrosion Damage into F-111 Fatigue Life Modelling |
JUN 2002 |
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| Authors:
T. Mills; P. K. Sharp; C. Loader; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION CANBERRA (AUSTRALIA)
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| In this report, an Equivalent Crack Size (ECS) approach is assessed and implemented for corrosion pittIng in D6ac steel. Relationships between physical corrosion morphology and fatigue life of laboratory coupons were established that allowed corrosion pits to be described as cracks to provide input for durability and damage tolerance analyses. Using the ECS relationship, fatigue lives were accurately predicted in complex coupons tested under spectrum loading. Details are provided on ... |
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| The Role of Marine Bacteria in Stainless Steel Pitting |
JAN 2002 |
17 pages |
| Authors:
RIchard I. Ray; Brenda J. Little; Jason S. Lee; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
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| Flat plate and welded stainless steel coupons (316L, Nitronic 50 an AL6xN) were evaluated for potential microbiologically influenced corrosion in seawater. No pitting was observed in flat plate of welded AL6xN under the exposure condition after one year. Pits were located at welds of Nitronic 50 and 316L stainless steels after six- and eight-week exposures. In all cases, large numbers of bacteria were associated with the corrosion products. No corrosion ... |
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| Automated Corrosion Detection Program |
OCT 2001 |
117 pages |
| Authors:
Wally Hoppe; Jennifer Pierce; Ollie Scott; DAYTON UNIV OH RESEARCH INST
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| An evaluation of several hidden corrosion-detection technologies was performed using a probability of detection (POD) method for percent material loss that is similar to well -established crack detection assessment methods. Several other tasks were performed, with overall goal of contribution to aging aircraft maintainability improvement. Automation concepts were studied and tested for improved speed and accuracy. Nondestructive Evaluation (NDE) requirements were surveyed within the industry for issues and needs pertaining ... |
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| The Influence of Surface Treatments on Micropitting and Scuffing |
01 MAY 2001 |
31 pages |
| Authors:
M. P. Alanou; R. W. Snidle; H. P. Evans; WALES UNIV CARDIFF
|
| This is the final report of the contract issued on 1 May 2001; this contract was a follow-on of contracts N68171-98-M-5294 and N68171-99-M-6457. Hence this report is based on an update of actions described in previous interim reports either covered by contracts N68171-98-M-5294, N68171-99-M-6457 or by the current contract. The focus of the current contract was on the scuffing performance of an ultra hard thin coating optimized for gearing applications. ... |
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| Minimizing Load Effects on NA4 Gear Vibration Diagnostic Parameter |
05 APR 2001 |
12 pages |
| Authors:
Paula J. Dempsey; James J. Zakrajsek; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| NA4 is a vibration diagnostic parameter, developed by researchers at NASA Glenn Research Center, for health monitoring of gears in helicopter transmissions. NA4 reacts to the onset of gear pitting damage and continues to react to the damage as it spreads. This research also indicates NA4 reacts similarly to load variations. The sensitivity of NA4 to load changes will substantially affect its performance on a helicopter gearbox that experiences continuously ... |
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| Corrosion and Corrosion Fatigue of Airframe Materials |
JUL 2000 |
79 pages |
| Authors:
Robert P. Wei; LEHIGH UNIV BETHLEHEM PA DEPT OF MECHANICAL ENGINEERING AND MECHANICS
|
| This report summarizes research performed under Grant 92-G-0006 and complementary programs sponsored by the Air Force Office of Scientific Research under Grants F49620-96-1-0245 and F49620-9g-1-0198. The objectives of these programs are (1) the development of a basic understanding of the processes of localized corrosion and corrosion fatigue crack nucleation and growth in high strength aluminum alloys used in airframe construction, (2) the formulation of ... |
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| Surface Fatigue Lives of Case-Carburized Gears With an Improved Surface Finish |
APR 2000 |
15 pages |
| Authors:
T. L. Krantz; M. P. Alanou; H. P. Evans; R. W. Snidle; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Previous research provides qualitative evidence that an improved surface finish can increase the surface fatigue lives of gears. To quantify the influence of surface roughness on life, a set of AISI 9310 steel gears was provided with a near-mirror finish by superfinishing. The effects of the superfinishing on the quality of the gear tooth surfaces were determined using data from metrology, profilometry, and interferometric microscope ... |
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| Experimental Study of Metal Corrosion in Supercritical Brines: Application to Supercritical Water Oxidation of Hazardous Wastes |
31 MAR 2000 |
65 pages |
| Authors:
Scott A. Wood; Leslie L. Baker; IDAHO UNIV MOSCOW DEPT OF GEOLOGY ANDGEOLOGICAL ENGINEERING
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| The corrosion behavior of Hastelloy C, ticanium, zirconium, niobium, tantalum, and gold have been studied as a function of temperature (200 degrees - 4000 degrees C), acid concentration (0 0.02 mol/Kg), oxygen content (0.1-1 mol %) and NaCi content (0-0.2 mol/Kg). The intent of these experiments was to determine an empirical rate law for corrosion of these metals as a function of the parameters listed above. ... |
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| Review of Fatigue of Coatings/Substrates |
2000 |
13 pages |
| Authors:
K. Sadananda; R. L. Holtz; NAVAL RESEARCH LAB WASHINGTON DC MATERIAL SCIENCE AND TECHNOLOGY DIV
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| A review of fatigue of coatings/substrates is presented. Fatigue damage is either local or general, depending on the range of cyclic loads. Local fatigue damage includes rolling contact fatigue (RCF), fretting fatigue, fatigue-wear and general wear. Applied loads are localized consisting of rolling contacts or sliding contacts, and the resulting damage is mostly surface related. Crack initiation, surface pitting, delamination, spalling, buckling and enhanced wear can result from local fatigue ... |
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| T-55 Engine Compressor Stator Vane Investigation |
NOV 1999 |
69 pages |
| Authors:
Scott M. Grendahl; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| The U.S. Army Aviation and Missile Command (AMCOM) requested the U.S. Army Research Laboratory Weapons and Materials Research Directorate (ARL-WMRD) investigate a corrosion problem with T-55 engine stators. This investigation was part of a second source vendor qualification in which a specific vendor was failing the engine test due to significant corrosion. The stators were virtually identical before the engine test and seemingly had passed all qualification ... |
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| Investigation of a Roof Tube Failure from a Utility Boiler |
JUN 1999 |
23 pages |
| Authors:
David A. Shifler; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD SURVIVABILITY STRUCTURES AND MATERIALS DIRECTORATE
|
| A recent failure from the roof tube section of No. 3 Boiler at IHDNSWC, Indian Head, MD occurred. Evaluation of the tube failure indicated extremely heavy waterside deposits that had migrated from other areas of the boiler. These deposits led to local overheating and creep rupture on the hot crown of the roof tube. Waterside pitting accentuated the applied tube stresses and decreased the time to rupture. The boiler should ... |
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| Spatial and Temporal Relationships Between Localized Corrosion and Bacterial Activtty on lron-Containing Substrata |
JUN 1999 |
5 pages |
| Authors:
M. Franklin; B. J. Little; R. I. Ray; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| A series of laboratory and field experiments were designed to determine the temporal and spatial relationships between accumulations of bacteria and pitting corrosion of iron-containing metals exposed in fresh and marine electrolytes. Abiotic corrosion was established in both carbon and stainless steels prior to the introduction of viable and glutaraldehyde-fixed bacteria in fresh water and seawater media. In all cases a spatial relationship between accumulations of cells and localized corrosion ... |
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| Characterization of Materials Degradation due to Corrosion and Fatigue in Aerospace Structures |
13 MAY 1999 |
17 pages |
| Authors:
A. K. Mai; J. M. Yang; K. Ono; CALIFORNIA UNIV LOS ANGELES SCHOOL OF ENGINEERING AND APPLIEDSCIENCE
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| Research was carried out in two related areas: (1) the degradation inthe load carrying capacity of the structural components, and (2) nondestructive evaluation (NDE) for characterization of the degradation. In the first topic, the effect of pitting corrosion on the strength of aircraft grade aluminum alloys was studied through laboratory tensile and fatigue tests and theoretical modeling. The probability of failure in the presence of multiple pits was found to ... |
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| Non - Chromium Conversion Coatings on Aluminium |
31 DEC 1997 |
36 pages |
| Authors:
A. Bodnevas; O. Berkh; G. Rogalsky; M. Rotel; J. Zahavi; ISRAEL INST OF METALS HAIFA
|
| In the current period our efforts were concentrated on the without chromate passivation of Al 2024-T3. This material in known to be very prone to both pitting and intergranular corrosion owing to high Cu content (its composition-4.5% Cu, 1.5% Mg, 0.6% Mn) and heat treatment prehistory (solution heat- treated, then strain-hardened). Corrosion accelerates especially in the presence of halogen ions. The actual mechanism by which the Cl- or F- ions ... |
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| Corrosion of Metal Matrix Composites |
NOV 97 |
43 pages |
| Authors:
Ian W. Hall; DELAWARE UNIV NEWARK DEPT OF MATHEMATICAL SCIENCES
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| Long term immersion testing and short term electrochemical testing have been carried out on two metal matrix composites and their corresponding unreinforced alloys. The composites were 15% alumina reinforced 6061-Al alloy and an Al-Si alloy reinforced with 20, 30, 40 or 55% SiC particles. It is shown that the pitting potentials are essentially independent of the presence or absence of reinforcement particles, as well as of their volume fraction. Corrosion ... |
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| Prediction of Hydrogen Entry and Permeation in Metals and Alloys |
OCT 97 |
31 pages |
| Authors:
H. W. Pickering; PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| The objectives of this research were to understand the mechanism of hydrogen entry into metals and to search for and evaluate various remedial measures to control this process and the subsequent hydrogen embrittlement. Several parallel approaches were pursued to achieve these objectives. A brief description is given in the report on each of these following tasks: Twenty-two research and review papers were published or submitted to journals which describe the ... |
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| Part I. The Effect of Dissolved Ozone on the Corrosion Behavior of Stainless Steels in Artificial Seawater. Part II. The Effect of Dissolved Ozone on the Corrosion Behavior of Ni-Cr-Mo Alloys in Artificial Seawater |
JAN 97 |
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| Authors:
W. E. Wyllie Ii; D. J. Duquette; B. E. Brown; RENSSELAER POLYTECHNIC INST TROY NY
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| The corrosion resistance of austenitic stainless steels in artificial seawater containing 0.2 to 0.4 mg/L dissolved ozone was investigated. According to cyclic polarization data, UNS S30400 and S31600 stainless steels are resistant to pit initiation after 8 weeks exposure to ozonated artificial seawater. However, if crevices exist, crevice corrosion is more severe in ozonated vs. aerated artificial seawater. Maximum crevice corrosion penetration rates of 8 and 5 mm/y were recorded ... |
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| The Influence of Crystal Orientation on the Corrosion Behavior of Aluminum |
1997 |
107 pages |
| Authors:
Brandon W. Davis; NAVAL ACADEMY ANNAPOLIS MD
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| Observations have been made which indicate that the pitting of aluminum is crystallographic. When pure aluminum pits, the resulting morphology of the pit is composed of (100) orientations. Metastable and stable pitting was examined for (100), (110), and (111) aluminum single crystals and polycrystalline aluminum with 99.99% purity. Evidence was seen that the (111) orientation had a higher affinity for initiation and propagation and the (100) orientation had the least ... |
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| Nondestructive Detection and Characterization of Corrosion in Aircraft |
NOV 96 |
9 pages |
| Authors:
James H. Rose; John C. Moulder; Joseph N. Gray; IOWA STATE UNIV AMES CENTER FOR NONDESTRUCTIVE EVALUATION
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| We have developed a fully characterized pulsed eddy current (PEC) instrument to detect and characterize second-layer corrosion in aircraft skin. In the first year, we developed the theory needed to accurately model the response of the PEC instrument measured on a variety of calibration specimens. In the second year, we made experimental measurements on a number of realistic samples including a corrosion test panel provided by Boeing corporation. In addition, ... |
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| Scanning Tunneling Microscopy Studies of the Morphology and Kinetic Pathways for Corrosion Reactions of Stressed Materials |
NOV 96 |
16 pages |
| Authors:
Steven J. Sibener; CHICAGO UNIV IL DEPT OF CHEMISTRY
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| This research program improved our understanding of how surface chemical reactions, surface stress, and atomic level microstructure influence materials oxidation/corrosion processes. Central to this effort was the construction of a new scanning probe microscopy facility which now houses a UHV- STM and a combined STM/AFM for operation in both air and electrochemical environments. It was demonstrated that applied stress fields can influence the electrochemical pitting corrosion chemistry of pure aluminum ... |
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| Experimental Evaluation of Face Gears for Aerospace Drive System Applications |
SEP 96 |
11 pages |
| Authors:
Robert E. Handschuh; David G. Lewicki; Gregory F. heath; Robert B. Bossier Jr; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CEN TER
|
| The experimental evaluation of face gears has been ongoing at NASA lewis since 1991. Testing to date has focused on the feasibility of using this gear mesh to transfer power between intersecting shafts as found in helicopter main rotor transmissions. The focus of the experiments has been to deternaine the failure modes and load capacity of this gear mesh operated in a simulated helicopter transmission environment. At this time tests ... |
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| Parallel Fabrication and Electronic Characterization of Nanostructured and Nanoheterostructured Metal Surfaces |
12 FEB 96 |
6 pages |
| Authors:
Kenneth Douglas; COLORADO UNIV AT BOULDER DEPT OF PHYSICS
|
| We have been pursuing the creation of quantum dot arrays fabricated in crystalline silicon. We wish to produce a two-dimensional array of crystalline Si(c-Si) quantum dots or boxes surrounded by a hydrogenated amorphous Si(a-Si:H) matrix. The quantum dots are to be defined spatially using the protein crystal masking technique described in our research grant and which we now briefly summarize. This nanofabrication technique is implemented using two-dimensional crystalline protein monolayers ... |
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| Characterization of Early Stages of Corrosion Fatigue in Aircraft Skin |
FEB 96 |
147 pages |
| Authors:
C. G. Schmidt; J. E. Crocker; J. H. Giovanola; C. H. Kanazawa; D. A. Shockey; SRI INTERNATIONAL MENLO PARK CA
|
| SRI International is conducting research to characterize and quantitatively describe the early stages of corrosion fatigue in the fuselage skin of commercial aircraft. Specific objectives are to gain an improved deterministic understanding of the transition from corrosion pit to short crack to long crack and to delineate the effects of environment, skin surface condition, and loading conditions on crack nucleation and propagation rates. This Phase I report summarizes the effort ... |
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| Corrosion and Corrosion Fatigue of Airframe Materials |
FEB 96 |
56 pages |
| Authors:
Robert P. Wei; D. G. Harlow; LEHIGH UNIV BETHLEHEM PA DEPT OF MECHANICAL ENGINEERING AND MECHANICS
|
| In support of the National Aircraft Research Program of the Federal Aviation Administration (FAA) Lehigh University undertook a multidisciplinary program of research to study corrosion and corrosion fatigue of airframe materials. The program is complemented by a program sponsored by the Air Force Office of Scientific Research (AFOSR). The objectives of these programs are (1) the development of basic understanding of the processes of localized corrosion and corrosion fatigue crack ... |
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| Novel Electrolytes for the Electrochemical Machining of Air-Breathing Propulsion Materials |
26 JAN 1996 |
58 pages |
| Authors:
James H. White; James A. Marvin; Anthony F. Sammells; ELTRON RESEARCH INC BOULDER CO
|
| This investigation was directed towards developing novel ElectroChemical Machining (ECM) technology for the processing of titanium alloys for application in air breathing propulsion systems by Naval Aircraft. The feature of this approach relies upon the application of unique heterogeneous electrolytes consisting of dispersions of electronically conducting particles within an ionically conducting aqueous phase. This resulted in effectively extending the cathode into close proximity to ... |
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| Variability of Fatigue Crack Growth Properties for 2024-T3 Aluminium Alloy |
19 JAN 1996 |
36 pages |
| Authors:
A. Oldersma; R. J. Wanhill; NATIONAL AEROSPACE LAB AMSTERDAM (NETHERLANDS)
|
| Discussions between D-BAA and the NLR have shown that significant variability in fatigue crack growth properties is possible for the industry standard damage tolerant aluminum alloy, 2024-T3 sheet. This is important for two reasons: (1) design assumptions and (2) comparisons of different candidate materials, such as 6013-T6, with 2024-T3. Another important topic is the possibility of changes in damage tolerance properties owing to long term natural aging. In this report ... |
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| Establishment of an Integrated Confocal Microscopy Facility for ONR biofouling/Biocorrosion Researchers |
96 |
2 pages |
| Authors:
Robert J. Palmer; TENNESSEE UNIV KNOXVILLE
|
| In contrast to the formerly standard techniques that relied upon fixed, dehydrated biofilm samples (electron microscopy, light microscopy of sectioned biofilms), the advent of the CLM has allowed researchers to study living microbial biofilms in situ morphology. |
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| Selected Energy Epitaxial Deposition and Low Energy Electron Microscopy of AlN, GaN, and SiC Thin Films |
DEC 95 |
28 pages |
| Authors:
R. F. Davis; H. H. Lamb; I. S. T. Tsong; NORTH CAROLINA STATE UNIV AT RALEIGH
|
| As-received wafers of n- and p-type 6H-SiC(0001) were etched via gaseous HCl in H2 at 1350 deg C at NASA-Lewis to remove cutting and polishing scratches from the surface; however, etch pits were created. GaN films have been deposited on Si(100) and Al2O3(0001) substrates using triethylgallium and NH3 seeded into highly expanded He gas streams. A two-step deposition process that repeatedly resulted in continuous crystalline GaN films has been developed. ... |
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| Corrosion Inhibition by Plasma Ion Implantation |
26 JUN 95 |
33 pages |
| Authors:
J. R. Roth; Raymond A. Buchanan; TENNESSEE UNIV KNOXVILLE
|
| Research Office Contract DAAL-03-89-G-0104. Accomplishments during this four year period include building up an operational plasma ion implantation facility, the successful plasma ion implantation of aluminum and stainless steel with nitrogen ions, and the demonstration of significantly increased corrosion resistance and pitting potential in these metals. During the course of exploratory research activities, the regimes of ion energy, implantation voltage, and dose were identified which produced significantly improved corrosion resistance, ... |
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| Detecting Gear Tooth Fracture in a High Contact Ratio Face Gear Mesh |
JAN 95 |
13 pages |
| Authors:
James J. Zakrajsek; Robert F. Handschuh; David G. Lewicki; Harry J. Decker; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CEN TER
|
| This paper summarizes the results of a study in which three different vibration diagnostic methods were used to detect gear tooth fracture in a high contact ratio face gear mesh. The NASA spiral bevel gear fatigue test rig was used to produce unseeded fault, natural failures of four face gear specimens. During the fatigue tests, which were run to determine load capacity and primary failure mechanisms for face gears, vibration ... |
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| Chemically Induced Passivity of Aluminum Alloys and Al-Based Metal Matrix Composites |
JAN 95 |
66 pages |
| Authors:
Florian Mansfeld; Y. Wang; UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES DEPT OF MATERIALS SCIENCE
|
| The concept of surface modification has been applied for corrosion protection of commercial aluminum alloys such as Al 2024, Al 6013, Al 6061 and Al 7075. The goal of this project was to develop methods of corrosion protection which do not use toxic chemicals. The Ce-Mo process consisting of immersion in hot solutions of CeC13 and Ce(N03)3 followed by anodic polarization in a molybdate solution has produced surfaces with exceptional ... |
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| Morphology of Extinguished Monolithic JA2 Grains Fired in a 30-MM Solid Propellant Electrothermal-Chemical (SPETC) Gun |
NOV 94 |
33 pages |
| Authors:
Robert J. Lieb; Christopher J. Gillich; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Monolithic grains of JA2 were fired in a 30-mm solid propellant electrothermal-chemical (SPETC) gun and were recovered after self-extinguishing because of depressurization. A morphological investigation was performed on these grains to gain insight into the interaction between the plasma and the propellant. Scanning electron microscopy (SEM) was used to characterize the morphology of the combustion surface and bulk of the propellant. Results show that the propellant burning surface was pitted ... |
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| Analytical and Experimental Vibration Analysis of a Faulty Gear System |
OCT 94 |
19 pages |
| Authors:
F. K. Choy; M. J. Braun; V. Polyshchuk; J. J. Zakrajsek; D. P. Townsend; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CEN TER
|
| A comprehensive analytical procedure was developed for predicting faults in gear transmission systems under normal operating conditions. A gear tooth fault model is developed to simulate the effects of pitting and wear on the vibration signal under normal operating conditions. The model uses changes in the gear mesh stiffness to simulate the effects of gear tooth faults. The overall dynamics of the gear transmission system is evaluated by coupling the ... |
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| Identification of Resonant, Two-Electron, and Inter-Atomic Features in K and L(sub23) NEXAFS Spectra |
SEP 94 |
9 pages |
| Authors:
H. Sambe; X. Qian; David E. Ramaker; W. E. O'Grady; GEORGE WASHINGTON UNIV WASHINGTON DC DEPT OF CHEMISTRY
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| Experimental Cl K NEXAFS spectra for Cl- hydrated in H20, and on passivated Al electrodes (below and above the pitting potential) have widely different spectral line shapes. Experimental K-and L23-edge NEXAFS data for the alkali halides and rare gas solids are compared with FEFF6 calculated results to optimize code input parameters, test code validity, and identify many-body features in these model systems. Differences are shown to arise from many-body shake-up ... |
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| Corrosion of Aircraft Materials: Correlation Between Nanometer Scale and Macroscopic Structural Damage Parameters |
15 AUG 94 |
8 pages |
| Authors:
A. Gonzales-Martin; D. Hodko; C. Andrews; O. J. Murphy; LYNNTECH INC COLLEGE STATION TX
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| The following work has been carried out during the reporting period: (1) imaging of pitting corrosion initiation in aluminum at the nanometer scale, (2) study of the effects of main atmospheric pollutants on the initiation of the corrosion process; (3) identification of surface regions at an aluminum sample where corrosion is most likely to occur; (4) measurements of the electrochemical impedance spectra on Al sample before and during the pitting ... |
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| Passivation of Metals and Semiconductors. Proceedings of the International Symposium on Passivation of Metals and Semiconductors Held in Clausthal, Germany on August 21 - 16, 1994 |
AUG 94 |
1067 pages |
| Authors:
K. E. Heusler; TECHNISCHE UNIV CLAUSTHAL CLAUSTHAL- ZELLERFELD (GERMANY F R) INST FUER META LLKINDE UND METALLPHYSIK
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| Proceedings of the USAF Structural Integrity Program Conference Held in San Antonio, Texas on November 30-December 2, 1993 |
AUG 94 |
646 pages |
| Authors:
Thomas D. Cooper; John W. Lincoln; James L. Rudd; WRIGHT LAB WRIGHT-PATTERSON AFB OH
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| The purpose of this 1993 Conference was to bring together technical personnel in DoD and the aerospace industry who are involved in the various technologies required to ensure the structural integrity of aircraft gas turbine engines, airframes and other mechanical systems. It provided a forum to exchange ideas and share new information relating to the critical aspects of durability and damage tolerance technology for aircraft systems. |
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Reports by Keyword(s)
PITTING
