bluuebunny/crossref_metadata_2025 huggingface dataset:
Combustion Testing of Metallic Materials Aboard the NASA Johnson Space Center's KC-135
Authors: Steinberg TA , Stoltzfus JM
Published: March 2009

NASA White Sands Test Facility and The Department of Mechanical Engineering at The University of Queensland have begun a collaborative research program investigating the effects of gravity on the burning characteristics of metallic materials. This work builds upon the earlier short-duration ground-based testing where it was indicated that certain metallic materials that would not sustain combustion at high-oxygen pressure in normal gravity, appeared to support combustion at a relatively lower oxygen pressure in microgravity. These earlier tests, of 2.2 s duration, did not allow slow burning materials, or materials that were difficult to ignite, adequate time to propagate. A specific objective of this research program, therefore, was to perform microgravity tests of substantially longer duration thus allowing these materials, if flammable, adequate time to propagate along the test specimen. The NASA Johnson Space Center's KC-135 Reduced Gravity Test Aircraft, providing a microgravity duration of 24 – 26 seconds per experiment, was selected for these tests. This paper provides a description of the test system designed and fabricated to conduct these tests, the procedure used to conduct flight based tests aboard NASA Johnson Space Center's KC-135, and an overview of the actual flights and the experimental results. System modifications made in preparation for the second series of flight tests, as a result of experiences during the first series of tests, are also described. Nine metallic materials were tested in this program including iron, nickel, copper, cobalt, aluminum, aluminum/10% silicon-carbide, titanium, Monel K-500, and 316 stainless steel. The results of these microgravity tests, consistent with the results from the earlier short-duration tests, are described and comparisons made for these materials with results obtained in similar normal gravity tests.
Flammability Tests of Miniature Brazed Aluminum Heat Exchangers in Liquid Oxygen
Authors: Zawierucha R , Million JF
Published: March 2009

Most air separation plants currently in use employ compressors to increase oxygen pressure for customer usage. An alternative approach is to extract liquid oxygen from the separation column which is pumped to higher pressure and then boiled in a heat exchanger to directly provide an elevated pressure gaseous oxygen product. Brazed aluminum heat exchangers (BAHX) are normally utilized as the product oxygen vaporizers. The process results in substantial contact between high pressure liquid oxygen and aluminum material. The increased use of BAHXs to produce pressurized oxygen as an alternative to the use of oxygen compressors led to a series of experimental programs pertinent to the safe use of BAHXs for boiling oxygen at elevated pressures.

In the 1993 to 1995 period, 29 individual flammability experiments were conducted with 3 kg or 13 kg miniature headered BAHX samples. In the oxygen passages, commercial purity liquid oxygen was used at pressures ranging from 170 kPa to 6,996 kPa. Alternate passages contained air, nitrogen or oxygen at pressures ranging from 108 kPa to 10,443 kPa. Nichrome wire was used to ignite hydrocarbons placed within an oxygen passage to simulate a promoted ignition event.

The experiments provided insights into the combustion inhibition mechanisms in BAHXs used for producing pressurized oxygen. Data cited form a part of the technical basis for a Compressed Gas Association pamphlet entitled: “Safe Use of Brazed Aluminum Heat Exchangers for Producing Pressurized Oxygen”.
Oxygen Compatibility of FKM Elastomers
Authors: D'Imperio VJ , Werley BL
Published: March 2009

FKM fluoroelastomers have been among the more compatible of soft goods for use in oxidizer systems. In recent years a number of new formulations have become available. Test data assessing oxygen compatibility for several recent formulations is compared with historical formulations. Comparisons are also noted between FKM, FFKM, and traditional elastomers. General conclusions on oxygen compatibility of FKM elastomers are drawn with respect to filler materials and fluorine content.
Ignitibility of Advanced Composites in Liquid and Gaseous Oxygen
Authors: Beeson HD , Hshieh FY , Hirsch DB
Published: March 2009

The ignitibility of epoxy, phenolic, bismaleimide, and vinyl/ester composites in liquid and gaseous oxygen was studied using the autoignition temperature test method of ASTM G 72 and the mechanical impact test methods of ASTM G 86 and ASTM D 2512. The heat of combustion of composites was also determined using the test method of ASTM D 240 to assess the fire hazards of composites once they ignited and burned. The results of this study indicate that the ignitibility of composites upon mechanical impact in liquid and gaseous oxygen is very complicated because the ignition mechanisms involve not only the thermal stability of organic resins but also the mechanical properties of fibers and material interactions in the composites and the heat transfer in and between organic resins, reinforced fibers, and surrounding fluids. The applicability of test methods to the assessment of ignitibility of composites is also discussed.
Arizona's SHRP Experience
Authors: Way GB
Published: March 2009

The Arizona Department of Transportation (ADOT) continues to be interested in improving pavement performance and, thus, is a strong supporter of the Strategic Highway Research Program (SHRP).The main focus of this paper is on five test projects including two with SPS-9 test sections built since 1993. The purpose of these projects is to learn more about SHRP binders and how they perform in Arizona's climate, and to review and try the SHRP mix design and SHRP testing as it applies to predicting future rutting and cracking, thus improving ultimately pavement performance. The knowledge gained from this work is being used by an Arizona SHRP implementation team representing ADOT, the Federal Highway Administration (FHWA), academe, and industry. The team's goal is to implement those elements of SHRP that are practical, beneficial, and cost effective. Based substantially upon this work, Arizona has adopted significant changes to specifying the quality of the aggregate crushing in order to address rutting on high traffic loading highways. In addition, Arizona will adopt the SHRP performance grading system for asphalt binders in calendar year 1997.
Evaluation of Superpave Binder Specification with Performance of Polymer-Modified Asphalt Pavements
Authors: Dongré R , Button JW , Kluttz RQ , Anderson DA
Published: March 2009

This paper discusses the evaluation of Superpave binder specification using pavements constructed with polymer-modified asphalt binders. Performance data collected from pavement test sections constructed in Sherman and Texarkana, Texas, were used in this evaluation. The Sherman pavement sections were overlays constructed in 1986 on US-75 whereas the Texarkana sections were all new construction on US 59/71 in late 1986 and early 1987. Dense-graded hot-mix asphalt (HMA), which contained 16-mm (5/8-inch) maximum size aggregate, was used. The aggregate comprised crushed limestone and field sand. Traffic loading and performance data were collected for both sites. Superpave binder tests were conducted on original asphalt binders saved from the construction projects. Superpave Performance Grade (PG grade) were then established for these binders. Predicted performance from the Superpave PG grades was compared against the field performance. Results indicate that the Superpave rutting parameter predicts rutting resistance reasonably accurately. It was found that the accuracy of prediction of thermal cracking is improved if failure properties are also considered. Finally, it was shown that the Superpave fatigue parameter needs reevaluation.
Designing Recycled Hot Mix Asphalt Mixtures Using Superpave Technology
Authors: Kandhal PS , Foo KY
Published: March 2009

Mix design procedures for recycled asphalt pavements require the selection of virgin asphalt binder or recycling agent. This research project was undertaken to develop a procedure for selecting the performance grade (PG) of virgin asphalt binder based on the Superpave PG grading system. Blending charts, similar to the viscosity blending charts, were constructed and evaluated based on test parameters obtained from the dynamic shear rheometer (DSR). The criteria for selection was based on Superpave performance grading (PG) specification, for example, G*/sinδ=1 kPa minimum for unconditioned asphalt binder, G*/sinδ=2.2 kPa minimum for rolling thin film oven (RTFO) residue, and G*sinδ=5 MPa maximum for RTFO and pressure aging vessel (PAV) residue. The criteria based on the fatigue parameter (G*sinδ=5 MPa maximum for RTFO+PAV residue) was determined to be too liberal and, therefore, was not recommended. An alternative criteria based on the high temperature stiffness (G*/sinδ) was recommended.
Window Detailing Considerations for Leakage Prevention
Authors: Lies KM , Faith BA
Published: March 2009

The focus of this paper is on the design development considerations for window detailing to prevent water leakage. Architectural design and detailing considerations discussed include: performance criteria; secondary flashing systems; integration with facade waterproofing; air seals; sealant selection and joint geometry; mullion and stack joint options; fastener locations and selection; and effects of product non-performance. Each of the design considerations are discussed with their effects and role on the waterproof integrity of the building facade. Examples of conceptual details to address waterproofing issues are provided.
A Review of Pressure Equalization and Compartmentalization Studies of Exterior Walls for Rain Penetration Control
Authors: Quirouette RL , Rousseau J
Published: March 2009

Recent studies have demonstrated that the amount of water penetrating through cladding systems can be significantly reduced by integrating the rainscreen concept into their design. Research has also shown that the mean pressure difference across the cladding governs the significant amount of rain penetration. A study on compartmenting the cavity has indicated that the location of compartment seals and the placement of the vents are important considerations in the control of wind driven rain.
Repair Methods for Common Water Leaks at Operable Windows and Sliding Glass Doors
Authors: Beers PE , Smith WD
Published: March 2009

In areas with high annual rainfall amounts, such as Florida, water leakage through operable windows and sliding glass doors is common, particularly at multistory applications. Although each leak is unique to the product and project, certain trends have developed. Investigations of water leakage at many projects throughout Florida, particularly multistory condominiums, have revealed several common water leak sources.

Observations during storms and field water tests have revealed three typical types of leaks that most frequently occur. Water percolation between operable members and the frame occurs during wind driven rain storms. Leakage through the sliding glass door track or window sill can occur any time water is present in the assembly. Leakage through perimeter sealants is usually induced during a wind driven rain, but can also occur if there is standing water next to the assembly.
Remedial Repair Leak Prevention in Porous Stone Faced Precast Panels — a Case Study Option
Authors: Flood RS
Published: March 2009

A proposed leak repair scheme (tested per ASTM) could have significantly altered the aesthetic appearance of a 42 story, 600 ft. highrise office tower and adjacent lowrise auxiliary buildings in San Francisco, California. This case study describes an alternative leak repair scheme for the 1000+ panels of porous stone faced precast panel window wall, the objective of which was to retain the existing building appearance to the maximum extent feasible.

Water from panel perimeters, panel cracks, and stone anchor locations was leaking into the building around the windows and other areas. The remedial solution presented here focuses on the water in the cavity bounded by the porous stone faced pre-cast panel, the flush mounted aluminum and window frame, and the exterior and interior silicone sealant joints. The design methodology consisted of first minimizing water infiltration through the porous stone in a visually unobtrusive manner and second, channeling and controlling the remaining infiltrate to both the existing weep system and into newly created weeped jamb cavity reservoirs.

This option was implemented from the exterior, (using the building's window washing rig) on a mid-height in-situ panel, (selected for testing due to prior leak history). Readily available construction materials and methods were utilized. Upon completion, the repaired panel passed an extended duration ASTM E-1105-93 test. Substantially reducing water penetration into the composite panel and then controlling the remaining infiltrate, this ASTM tested leak repair option provided a functioning, cost competitive solution to the water intrusion problem without altering the existing building aesthetics.
Performance of Stucco-Clad Wood-Frame Buildings in a Temperate Rain Forest
Authors: Dell MJ , Liaw SB
Published: March 2009

The use of stucco cladding on wood-frame buildings is common construction for low-rise condominiums on the southwestern coast of Canada, a mild climatic region with heavy rainfall (temperate rainforest). This paper is a case study of severe deterioration that has occurred due to water ingress and resultant fungal attack at a condominium in Vancouver. The condominium was built in 1987 and consists of 3, four-storey buildings interconnected by exterior walkways. All buildings and walkways are of wood-frame construction, and the exterior walls are clad in conventional stucco. The causes of the water ingress and the subsequent deterioration are numerous, including: poor waterproofing membrane application; improper flashing terminations; and substandard stucco application. The following key issues will be illustrated in this case study: the implications of applying elastomeric coatings to wood structures already infected by fungi; the importance of proper waterproofing details in a wet climate; the implications of using waferboard sheathing as opposed to plywood; and techniques for repairing deteriorating wood-frame structures.
Investigation and Repair of Leakage Problems in Recently Constructed Curtain Walls
Authors: Rutila DA
Published: March 2009

Waterproofing problems with recently constructed curtain walls illustrate that some, well understood, principles of waterproofing continue to be violated during wall construction. The author finds that divided or fragmented responsibility for the design often leads to the lack of understanding of the waterproofing requirements. New problems are being invented/discovered during the design and construction of these curtain wall systems due to the lack of understanding of the design requirements. Design specifications, workmanship, and the management of construction all contribute to recent problems. This paper presents the author's experience investigating and repairing waterproofing problems in newly constructed curtain walls. The author presents examples of design, workmanship and construction management problems that contribute curtain wall leakage problems, and presents a summary of the repair design and implementation.

Designers must understand the difference between barrier (surface sealed) curtain wall systems and cavity wall systems. The design must reflect the selected concept(s) consistently through the details, and it must anticipate a reasonable level of workmanship. Contractors and construction managers contribute to waterproofing problems in modern curtain walls through their lack of understanding of the design principles and, therefore, their lack of knowledge of what is important to the waterproofing performance. When the managers and oversight professionals fail to understand the construction, their direction or lack of direction to the workers contribute to problems.
The Facts About Hose Testing
Authors: Hoigard KR , Kudder RJ
Published: March 2009

The authors performed laboratory testing to evaluate the behavior of the Monarch nozzle specified by the AAMA 501.2 leakage test method, and localized pressures generated by the water spray impact under various circumstances. Findings include: 1) The Monarch nozzle spray pattern is distinctly non-uniform. 2) The maximum pressures generated by the water spray are not at the center of the spray pattern, but in a concentric ring around the center. Under standard conditions, maximum pressures of 0.34 kPa (7 psf) were measured. 3) As the nozzle/target distance decreases, generated pressures increase significantly. At nozzle/target distances of 102 mm (4 in.), maximum pressures approached 2.15 kPa (45 psf). 4) Multi planar test areas like curtain wall and window systems with protruding mullions require special test techniques to assure similar test pressures are applied to the various exposed components.
Quality Control Procedures to Prevent Water Leakage Through Windows
Authors: Beers PE , Smith WD
Published: March 2009

Most water leakage problems through windows and doors are the result of installation errors. Even the best system designs cannot overcome poor installation techniques. Simple mistakes such as the omission of an internal seal can result in major water leakage that damages building interiors, upsets building occupants and often results in costly repairs.

By establishing a quality control procedure that specifically addresses windows and doors, common installation mistakes can be prevented. This paper will present a series of steps to follow before and during the construction process to insure proper installation of windows and other glazing products.
An Overview of Water Leakage Problems in Single-Family Residences Clad with Exterior Insulation and Finish Systems (EIFS)
Authors: Williams MF , Williams BL
Published: March 2009

Water leakage has occurred in numerous EIFS-clad residences in the U.S. Field investigations of North Carolina homes indicate that deficiencies within and between various building components are allowing water leakage. Moisture behind EIFS claddings has jeopardized the in-service durability of the EIFS as well as other building components. A brief history of EIFS provides a framework for understanding the water leakage problems in residential construction. A classification of leakage sources identified to date in the North Carolina investigations is provided. Window-related leaks are discussed, and a remedial detailing for the typical interface between EIFS and windows is provided.
A Brief History, Status, and Mission of ASTM Subcommittee A01.28 on Bearing Steels
Authors: Green WB
Published: March 2009

The first ASTM specification dealing with bearing steels was issued in 1942. We are not sure who worked on this original document,but we can guess they were working on it through the war years. Of course, bearings and the steels they were made from were very important to the war efforts on both sides. Since those days, a lot has happened. There are now 7 ASTM specifications dealing with bearing materials, and they are recognized around the world. These are living documents, under constant review, keeping up with the changing technology in steel making. They are among the most demanding ASTM specifications. This paper will present the beginnings, highlight the changes along the way, and give a projected outline of the changes that will take place in the future as we move into the 21st century.
Cleanliness Assessment : A Critical Review and a Real Need to Predict Rolling Contact Fatigue Behaviour
Authors: Auclair G , Ruby-Meyer F , Meilland R , Rocabois P
Published: March 2009

The refinement of secondary steelmaking processes allows the steelmakers to produce very low oxygen and sulfur bearing steel grades. As it was pointed out many times previously, the specifications in terms of the O and S contents and ASTM rating constitute a necessity but are not sufficient to guarantee good contact fatigue properties. As for hard materials like bearing steels, the fatigue endurance is directly a function of internal defects such as nonmetallic inclusions (nmi), a lot of investigations have been conducted during the last years in order to develop methods which can describe as accurately as possible the distribution of nmi in the steel matrix. While each method provides specific information concerning the nmi, further work is currently in progress to combine the results obtained from several methods to further improve the accuracy of the prediction of rolling contact fatigue behaviour. In the present paper an approach developed through our previous research work is described.
From Cleanliness to Rolling Fatigue Life of Bearings — A New Approach
Authors: Lormand G , Meynaud P , Vincent A , Baudry G , Girodin D , Dudragne G
Published: March 2009

One of the main causes of in-service spalling of bearing steels is fatigue crack initiation from non-metallic inclusions. At the present time, while the relationship between endurance and cleanliness of bearing steels is obvious, no quantitative relationship between them has been established. The aim of this paper is to present a new quantitative method which predicts the rolling fatigue life distribution of bearings. This approach is based on a model of fatigue crack initiation in the vicinity of an inclusion in the steel matrix and on a simple fatigue crack propagation relationship. This basic model is used in a statistical approach to describe the scatter of fatigue lives using the distribution of inclusions in the Hertzian zone. The fairly good agreement with fatigue results shows that this approach constitutes a real future tool for predicting the influence of the main material parameters on the fatigue life distribution of bearings.
Simulation of the Behaviour of Short Cracks at Inclusions Under Rolling Contact Fatigue Loading — Specially the Effect of Plasticity
Authors: Melander A
Published: March 2009

A finite element study was performed on driving forces of short cracks at inclusions in bearing steel exposed to rolling contact load. The inclusions were assumed to be elastic and the steel matrix was elasto-plastic with material parameters from cyclic loading tests. The surface load on the raceway was simulated with a moving Hertzian pressure distribution. An inclusion was situated in the steel below the raceway. Short cracks were allowed to grow from the inclusion between subsequent passages of the contact load. The inclusion had a size of 20νm in diameter. The cracks were oriented 45° to the rolling contact plane. Five inclusion configurations were considered, namely a pore, a manganese sulfide inclusion, a through-cracked alumina inclusion, an alumina inclusion which was uncracked but which could debond from the matrix and finally a titanium nitride inclusion. The driving forces of the cracks were evaluated in terms of energy release rates. The magnitudes of these rates were significantly influenced by inclusion type, crack configuration, crack length, Hertzian loading level and metal plasticity. A ranking list was made of the different inclusions with respect to expected detrimental effect on contact fatigue life.
What Happens to the Fatigue Limit of Bearing Steel Without Nonmetallic Inclusions? : Fatigue Strength of Electron Beam Remelted Super Clean Bearing Steel
Authors: Murakami Y , Toriyama T , Tsubota K , Furumura K
Published: March 2009

This paper has two objectives. The first is to propose a new inclusion rating method based on statistics of extreme. The new inclusion rating method is applied to the evaluation of inclusions contained in two super clean bearing steels with a total oxygen level of 5ppm and 8ppm.

The second objective is to investigate the critical lower bound of inclusion size which influences the fatigue limit. For this purpose, a special steel with extremely low inclusion content, the electron beam remelted super clean bearing steel(EB-CHR), was prepared. It is shown that by decreasing the size of inclusions, the detrimental effect of inhomogeneities larger in size than inclusions, becomes more important. The small inhomogeneity is thought to be a local imperfectly heat- treated structure, bainite.
Fatigue and Material Response in Rolling Contact
Authors: Voskamp AP
Published: March 2009

Metal softening, induced during the so-called third stage of material response to rolling contact loading, increases the probability of spalling fatigue failure. Metal softening in the most heavily loaded subsurface region leads to micro-plastic deformation noticeable from the occurrence of microstructural change. The probability of crack initiation increases with the growth of the plastically deformed subsurface region. Subsequent crack growth in that region is stimulated by the induced residual stress and texture. Fatigue failure in modern clean bearing steel develops only when the material has reached the third stage. The threshold to the third stage can be determined, and thus fatigue life can be assessed from observations of microstructural change. Examples are discussed of observed reduction of the ferrite {211} diffraction-line width in relation to observed endurance.
Bearing Steels in the 21st Century
Authors: Tsubota K , Sato T , Kato Y , Hiraoka K , Hayashi R
Published: March 2009

Oxygen content of bearing steel will be reduced to below 3 ppm in the year 2000 if current trend for the reduction of oxygen in the steel continues. As a result, size of oxide inclusions will become smaller and the fatigue life will be doubled. From the viewpoint of life prediction, cleanliness evaluation methods currently used are not effective. Inclusion Rating Method by Statistics of Extreme is useful for both cleanliness evaluation and fatigue life prediction. Bearings made of suitably heat treated carbon steels or low alloy steels, which possess equivalent fatigue properties to bearing steels, will increase owing to the requirement for lower cost and better formability.
Aapplication of Continuous Casting Steel 100CR6 (SAE 52 100) for Bearing Balls
Authors: Stahl F , Hirsch T , Mayr P
Published: March 2009

The objective of the investigation was to study the feasi-bility of applying continuous casting steel 100Cr6 (SAE 52100) for bearing balls. It was found that two of three continuous casted steel batches have longer or at least similar rolling contact fatigue lifetimes comparec to one ingot casted batch. For one of the continuous casted batches, the rolling contact fatigue lifetime was 30% less.

The micro- and macrostructure and the residual stresses below the surface of the balls were comparable. There is also no obvious difference between the four batches in the metallurgical parameters like contents of oxygen, titanium and sulphur as well as in the distribution of carbides and their network.

The reason for the shorter lifetime of one batch finally was found to be due not to the continuous casting process itself. There was a difference in the cross section of the different casting moulds, and by this in the speed of solidification. As a consequence an increased segregation of alloying elements was observed. So the primary carbides of this batch were of bigger size and higher amounts have been detected within a larger cross section of the bloom. Finally the inferior distribution and size of carbides in the layers of maximum equivalent stress below the surface were found to be crack initiation points. The reduced lifetime of one batch therefore could be correlated to these metallurgical differences.

It has been demonstrated that bearing balls made from continuous casted steel 100Cr6 (SAE 52100) have similar or better rolling contact fatigue lifetime than bearing balls made from ingot casted material. However, it is necessary to have minimal amounts of micro- and macro-inclusions as well as a homogeneous distribution of carbides, particularly in the main segregation areas. For that reason, the steel quality of every type of continuous casting machine has to be evaluated separately.
Case-hardening Medium Carbon Steel for Tough and Long Life Bearing under Severe Lubrication Conditions
Authors: Furumura K , Murakami Y , Abe T
Published: March 2009

It is known these days that case-hardening bearings have a longer life than through-hardening ones under severe lubrication conditions (i.e. mixing-in of foreign particles in the lubrication oil). To explain this fact, we first presented the mechanism of stress relaxation at the debris dent edge [1]. According to test results, it was found that both retained austenite and hardness are the most important factors for a longer life material.

Such material has a longer life even under boundary lubrication conditions. Since a sufficient EHL oil film does not form under boundary lubrication conditions, metal contact occurs. The resulting damage is called “peeling” and it decreases the bearing life.

To realize ideal case hardening material for bearings, a new carbo-nitride heat treatment has been developed. Normally, it is extremely difficult to obtain a sufficient case depth using a traditional carbo-nitride heat treatment process. As an alternate, medium carbon steel was studied. The application of newly developed medium carbon steel has not only proved to make the creation of a sufficient case depth easier, but also provided economic benefits. Based on results from testing both the dimensional stability and fracture toughness, newly developed medium carbon steel can be used for case-hardening bearings.
Study on the Limited Hardenability Steel
Authors: Xu LP , Li L , Min YA , Xu MH , Le JP , Liu RH
Published: March 2009

A series of measurements were taken in the limited hardenability bearing steel rings which were induction hardened and tempered. Measurements showed several features which strengthened the rings: (1) Compressive residual stress are generated from surface to a depth of 3.2mm and high residual compressive stress at the location where fatigue fracture initiates. (2) The matrix of the hardened layer was composed mainly of lath martensite with dispersed carbides whose formula was Me3 according to the X-ray spectrum analysis. The carbon content of martensite was estimated to be lower than 0.58% (by weight). The core was constituted of troostite transformed from spheroidal parbide. (3) The amount of retained austenite in the hardened layer was about 5% (in volume) which ensures the high dimensional stability of bearing.
Development of CSS-421™, A High Performance Carburizing Stainless Steel for High Temperature Aerospace Applications
Authors: Burrier HI , Tomasello CM , Balliett SA , Maloney JL , Milam DL , Ogden WP
Published: March 2009

Today's aerospace engineering challenges demand materials which can operate under conditions of temperature extremes, high loads and harsh, corrosive environments. This paper presents a technical overview of the on-going development of CSS-42L™ (US Patent #5,424,028) [1]. This alloy is a case — carburizable, stainless steel alloy suitable for use in applications up to 427°C (800°F), particularly suited to high performance rolling element bearings, gears, shafts and fasteners.

The nominal chemistry of CSS-42L™ includes: (by weight) 0.12% carbon, 14.0% chromium, 0.60% vanadium, 2.0% nickel, 4.75% molybdenum and 12.5% cobalt. Careful balancing of these components combined with VIM-VAR melting produces an alloy that can be carburized and heat treated to achieve a high surface hardness (> 58 HRC at 1mm (0.040 in) depth) with excellent corrosion resistance. The hot hardness of the carburized case is equal to or better than all competitive grades, exceeding 60 HRC at 427°C (800°F). The fracture toughness and impact resistance of the heat treated core material have likewise been evaluated in detail and found to be better than M50-NiL steel. The corrosion resistance has been shown to be equivalent to that of 440C steel in tests performed to date.
Metallurgical and Tribological Evaluation of 32CrMoV13 Deep Nitrided Steel and XD15N™ High Nitrogen Martensitic Steel for Aerospace Applications
Authors: Pichard I , Girodin D , Dudragne G , Moraux J-Y
Published: March 2009

Aerospace bearing applications are increasingly required to operate under very severe operational conditions in terms of speed, load, temperature and environment. Reliability is also required for safety concerns.

Therefore, each bearing application is carefully designed and the bearing steel selected to withstand these conditions.

To meet these requirements, deep nitriding of 32CrMoV13 steel and a new nitrogen martensitic steel have been developed.

The material properties of these steels in relation with manufacturing processes are presented and compared with usual steels.

The new steels provide in their respective coverage, better rolling contact fatigue life, mechanical properties and corrosion resistance.

Further characterizations are still in progress.
A New Corrosion Resistant, Martensitic Stainless Steel for Improved Performance in Miniature Bearings
Authors: Tomasello CM , Maloney JL , Ward PC , Materkowski JP
Published: March 2009

A new alloy, 440 N-DUR™∗ has been developed which will provide the corrosion resistance of 440C with improved carbide size and distribution for noiseless miniature precision bearing operation. The alloy may be through hardened to achieve a minimum hardness of 60 HRC. Its nominal composition is 0.65 wt.% C, 14.5 wt.% Cr, 0.30 wt.% Si, 0.45 wt.% Mn and 0.10 wt.% N2. The development of the alloy is a result of a factorial experimental design including 17 alloy variants. The optimum alloy provides a combination of the best carbide structure, corrosion resistance and heat treat response. The addition of nitrogen combined with this carbon and chromium content improves the alloy's hardenability and corrosion resistance. The alloy successfully withstands copper sulfate exposure and is currently being tested in several bearing applications. It also has great potential to outperform 440C and other corrosion resistant alloys for other ambient and low temperature applications because of its improved microstructure and heat treat response.
Laser Glazed Bearings
Authors: Hetzner DW
Published: March 2009

In the past decade high power, reliable, carbon dioxide lasers have become commercially available. Laser glazing is a process in which a focused laser beam is used to melt a very small portion of a component. As the beam moves away from the melted region, the underlying mass of the component causes the liquid pool to rapidly solidify. A major advantage of laser glazing is that the refined structure is only created in areas where high load carrying capacity is required

Initially rods manufactured from BG 42 and M 50 steels were laser glazed. Laser glazing transformed the normal, fine grain, martensitic steel matrix into a very fine dendritic microstructure. The carbides in the laser glazed material were greatly reduced in size due to very rapid solidification. Using a standard ball / rod rolling contact fatigue tester, enhanced rolling contact fatigue life was realized from the laser glazing process.

LM 12749 tapered roller bearing cones were fabricated from M 50 high speed steel and laser glazed. At 200% catalog load, the L15.9% life of the laser glazed M 50 bearings was 370% greater than the wrought cones. Similarly, when tested at 300% catalog load, the laser glazed bearings had L15.9% life 580% greater than the wrought cones.

Laser processing has been applied to 440 C stainless steel. In this alloy similar reduction in the size and distribution of large chromium carbides was achieved. The glazed 440 C was approximately 20 Knoop hardness points higher than the wrought alloy. Examples and properties of glazed microstructures in ball bearings and other alloy systems are discussed.
The Application of Resonance Ultrasound Spectroscopy to Bearing Rollers
Authors: Rhodes GW
Published: March 2009

If we apply continuous sweep of vibrational frequencies to a solid, the object will resonate, or ring just like a bell, provided the applied sound frequency matches one of the samples natural vibrational frequencies. The resonances of a solid are affected by its elastic properties, shape, size and density. Any deviation, from the ideal, (crack, grinding burn, dent, dimensional change, hardness difference…) changes the resonance spectrum. This technique is being used to rapidly sort axially symmetric roller bearing elements containing any of several flaws, independent of part orientation. The flaws of concern include: cracks (down to 1mm × 50 μm), dimensional and hardness deviations. Industrial bearing manufacturers have found that RUS was able to reliably find cracks which were missed by Eddy Current, whether the defects occurred on the body or end, and without appreciable false rejects. Simultaneous with crack examinations, RUS is able to measure the length of 15 mm tapered rolling elements to ±5μm. Specific data on crack determinations along with dimensional measurements will be presented.
Influence of UVB Radiation on Aquatic Ecosystems
Authors: Lean DRS
Published: March 2009

The impact of increased UVB (290–320 nm) radiation due to stratospheric ozone depletion is placed in context with how historical levels of both UVB and UVA (320–400 nm) have influenced the structure of aquatic communities and geochemistry of lakes and their drainage basins. Suggestions for the development of generalized models for predicting the impact of UV radiation are provided and illustrate that both the response of a particular process as a function of wavelength and reliable predictions for underwater spectral irradience are needed. Direct effects on organisms are discussed in light of problems due to adaptation, avoidance, repair and consequences of changes from sensitive to tolerant species composition. Indirect effects mediated through photochemically produced highly reactive reduced oxygen species are introduced and related to redox reactions and metal speciation using the mercury cycle as an example. Although neglected in existing global carbon budgets, UV radiation is responsible for significant release of carbon dioxide and carbon monoxide as well as many other organic metabolites from refractory dissolved organic carbon (DOC). Finally, it was argued that some lakes are losing the “sun screen” provided by DOC, the principal attenuator of UV radiation, due to increased acidification and lower DOC export due to the warmer drier climate conditions.
Problems in Conducting In-situ Experiments to Evaluate the Influence of UV-B Radiation on Amphibian Eggs and Larvae
Authors: Berrill M , Lean DRS
Published: March 2009

Amphibian embryos and tadpoles may be sensitive to UV-B radiation in shallow pond water, and methods are needed to conduct UV-B exposures in the field. We exposed embryos and tadpoles of a variety of southern Ontario species in small flow through containers in lake and pond conditions to UV-B radiation.. The containers were supported on anchored racks, were submerged just below the water surface, and were exposed to solar radiation, solar radiation with UV-B blocked by Mylar-D, and solar radiation augmented with artificial UV-B produced by UV-B lamps. We found that the containers could not protect the embryos and tadpoles from even minor wave action in the lake site; these containers will work only in very protected sites. Initially, containers exposed to solar radiation and to augmented UV-B radiation had lids of cellulose acetate. Pond and lab tests subsequently established that, if the cellulose acetate came in contact with the water, toxicity to tadpoles was very high even in darkness. Therefore we raised the containers on their racks so that their lids were no longer submerged. Because UV-B radiation attenuates very rapidly in water with high DOC concentrations, it is difficult to significantly increase UV-B levels in pond water below a few cm. In situ experiments such as these demonstrate that interactive and often uncontrollable environmental variables can mitigate or enhance the effects of UV-B radiation.
Establishment of Quality Assurance Procedures for Aquatic Toxicity Testing with the Nematode Caenorhabditis elegans
Authors: Freeman MN , Marse TJ , Williams PL
Published: March 2009

In this study initial data were generated to develop laboratory control charts for aquatic toxicity testing using the nematode Caenorhabditis elegans. Tests were performed using two reference toxicants: CdCl2 and CuCl2. All tests were performed for 24 h without a food source and for 48 h with a food source in a commonly used nematode aquatic medium. Each test was replicated 6 times with each replicate having 6 wells per concentration with 10±1 worms per well. Probit analysis was used to estimate LC50 values for each test. The data were used to construct a mean (¯x) laboratory control chart for each reference toxicant. The coefficient of variation (CV) for three of the four reference toxicant tests was less than 20%, which demonstrates an excellent degree of reproducibility. These CV values are well within suggested standards for determination of organism sensitivity and overall test system credibility. A standardized procedure for performing 24 h and 48 h aquatic toxicity studies with C. elegans is proposed.
Developmental Arrest in Grass Shrimp Embryos Exposed to Selected Toxicants
Authors: Wilson JEH
Published: March 2009

Excised embryos of the grass shrimp (Palaemonetes pugio) were exposed to single pulse concentrations of selected pollutants for 4 days. The following toxicity endpoints were monitored: rate of embryonic development, embryo mortality, and types of embryo malformation. Each endpoint exhibited concentration—response relationships which were modified by the embryonic age (hence stage) at which exposure commenced. Developmental retardation of up to 3 days was effected by phenol at 0.01% (V/V) and complete developmental arrest occurred at 0.05% and 0.1% (V/V). Similarly for methylene chloride, developmental retardation of 1–3 days were observed at 0.1% (V/V) depending on the age of the embryos at the start of the tests. At concentrations of > 0.5% (V/V), there was complete developmental arrest irrespective of the embryonic stage. With ethanol, developmental retardation of between 1 and 2 days resulted when embryos in stages 3–6 were exposed to 1 and 1.5% (v/v). Developmental retardation of 2 days was consistently observed at an exposure concentration of 2% (v/v) for all embryonic stages tested. Complete developmental arrest occurred at 2.5 and 5.0 % (v/v) when stages 3–6 were exposed. For potassium dichromate, exposure of stages 3–6 embryos to nominal concentrations of 50 – 500 mg/L did not produce any effect (except for tests with stage 6 which showed a 1 day delay). At 1 000 mg/L there was retardation of 0.5 –1 day, while 2 000 mg/L resulted in complete arrest. The morphological abnormalities of the embryos are described. The ecological significance of these findings and implications for the development of short-term toxicity tests using grass shrimp embryos are discussed.
Identification of Cytochrome P4501A Inducers in Complex Mixtures of Polycyclic Aromatic Hydrocarbons
Authors: Villeneuve DL , De Vita WM , Crunkilton RL
Published: March 2009

An in vitro ethoxyresorufin O-deethylase (EROD) assay was used to study the ability of individual polycyclic aromatic hydrocarbons (PAHs) and mixtures of PAHs to induce Ah receptor (AhR) mediated cytochrome P4501A activity in PLHC-1 fish hepatoma cells. The purpose was to identify the most potent inducers from a set of thirteen separate PAHs and describe interactions occurring in complex mixtures of these PAHs. Where possible, potency was expressed in terms of 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD) equivalents (TCDD-EQ) by normalizing the PAH results to a TCDD standard curve. The most potent inducers were benzo(k)fluoranthene > benzo(a) pyrene ≈ benzo(b)fluoranthene > chrysene ≈ benzo(a)anthracene. At equal concentrations, these PAHs yielded potencies of 1670, 940, 655, 255, and 185 pg TCDD-EQ/g, respectively. Analysis of various mixtures of the thirteen PAHs suggested that complex interactions may be occurring.
Characterization of Ambient Levels of Metals and Polycyclic Aromatic Hydrocarbons for Surficial Soil in the Urban Piedmont Region of New Jersey
Authors: Wong DMW , Sanders PF
Published: March 2009

This investigation implemented a statistically based sampling program to determine the ambient levels of metals and carcinogenic polycyclic aromatic hydrocarbons in municipalities that meet urban center population criteria within the Piedmont Region of New Jersey. New Jersey Department of Environmental Protection (NJDEP)'s geographic information system (GIS) and on-line aerial photography were used in the sampling sites selection process. For surveying of sampling locations, Global Positioning System (GPS) technology was used. For each location, 1 sample was collected at 0–15.2 cm and analyzed for 23 target analyte list metals, 6 carcinogenic polycyclic aromatic hydrocarbons, total organic carbon, pH, loss on ignition, and particle size. Detected concentrations would represent naturally occurring levels plus those resulting from diffuse anthropogenic pollution (DAP). Arsenic, cadmium, beryllium, and lead were detected in 13% of soil samples at concentrations above state-proposed cleanup criteria. Carcinogenic polycyclic aromatic hydrocarbons were also detected in 18% of the samples at concentrations above state proposed cleanup criteria.
Use of Selective Silver Impregnation of Neuronal Degeneration as a Biomarker for Assessing Organophosphorus-Induced Neuropathy in the Central Nervous System. A Review
Authors: Tanaka D , Bursian SJ
Published: March 2009

Exposure to selected groups of organophosphorus compounds has been shown to result in neuronal degeneration in both avian and mammalian nervous systems. Previous investigators, using hematoxylin and eosin stains, concluded that the degeneration resulting from exposure to these compounds was restricted to peripheral nerves and to long fiber tracts of the spinal cord and lower brainstem. We re-examined the results of exposure to the organophosphorus compounds tri-o-tolyl phosphate, diisopropylphosphoro-fluoridate, and triphenyl phosphite using a variant of the Fink-Heimer silver impregnation method. This method selectively stains degenerating axons and axon terminals. Chickens, Japanese quail, rats, and mature and immature ferrets were used in these studies because of their differential clinical susceptibility to organophosphorus compounds. Our results indicate that exposure to each compound may result in a variable amount of degeneration within selected nuclei and tracts in the brain and spinal cord. The amount of degeneration seen in each instance corresponds well with the severity of the resultant clinical signs. In addition, the locus and severity of neuronal degeneration is dependent on the particular compound used, the species of animal exposed, and the age of the animal at the time of exposure.