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Fox B.R.,University of Oregon | Brinich B.L.,University of Oregon | Male J.L.,Pacific Northwest National Laboratory | Hubbard R.L.,Lambda Technologies | And 3 more authors.
Fuel | Year: 2015

A film-shear reactor was used to significantly enhance the oxidative desulfurization (ODS) of model fuels using hydrogen peroxide as the oxidant. Significant increases in the amount of sulfur removed were seen in comparison to conventionally stirred ODS reactions. For example, up to 50% desulfurization occurred in a single pass of the model fuel through the film-shear reactor at 10°C. The desulfurization reactions were very fast in the reactor, occurring on the time scale of seconds to minutes. Desulfurization was studied under a variety of conditions, and a statistical design of experiment (DOE) showed that the fuel to oxidant ratio was the only statistically significant parameter to impact the extent of desulfurization: a larger amount of oxidant led to higher desulfurization. A variety of benzothiophene contaminants (benzothiophene, 2-methylbenzothiophene, 5-methylbenzothiophene, dibenzothiophene, and 4,6-dimethyldibenzothiophene) were examined, and the film-shear reactor was effective in removing all of these contaminants. The film-shear reactor was effective at both low (0.5-2.0 mL/min) and high (100-300 mL/min) flow rates. Experiments showed that oxygen in air was not an effective oxidant for ODS in the film-shear reactor. Experiments using Mo(CO)6 as a molecular thermometer showed that "hot spots" are not forming in the film-shear reactor, and thus the increase in the ODS rate cannot be attributed to intense thermal activation occurring within the film-shear reactor. It is suggested that superb mixing of the aqueous and fuel phases is responsible for the increased rate of ODS in the reactor. © 2015 Elsevier Ltd. All rights reserved.


Hubbard R.L.,Lambda Technologies | Michael Strain S.,University of Oregon | Willemsen C.,University of Oregon | Tyler D.R.,University of Oregon
Journal of Applied Polymer Science | Year: 2016

It is demonstrated for the first time that an epoxy thermoset resin can be cured at temperatures well below its Tg ∞. This study compared the use of a uniform variable frequency microwave (VFM) field to standard oven curing at temperatures above and below Tg ∞. Using Tg, tan δ, modulus, and FTIR measurements, it is shown that the reaction of BFDGE with MDA to attain a product with Tg ∞ of 133 °C is achieved by VFM at temperatures from 100 to 140 °C; in contrast, the thermal cure normally requires 170 °C to attain the same Tg ∞ and the same extent of cure. By following the pregel cure reaction with 13C-NMR spectroscopy, it was determined that the lower cure temperatures of VFM cure predominately lead to chain extension and smaller amounts of crosslinking compared to the thermal cure. To explain these results, it is suggested that, after gelation, with VFM cure there is higher mobility from dipole rotations that continues the cure to completion without vitrification. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44222. © 2016 Wiley Periodicals, Inc.


Bordelon D.E.,Johns Hopkins University | Goldstein R.C.,AMF Life Systems LLC. | Nemkov V.S.,AMF Life Systems LLC. | Kumar A.,Lambda Technologies | And 3 more authors.
IEEE Transactions on Magnetics | Year: 2012

In this paper, we describe a modified solenoid coil that efficiently generates high amplitude alternating magnetic fields (AMF) having field uniformity (≤10%) within a 125-cm 3 volume of interest. Two-dimensional finite element analysis (2D-FEA) was used to design a coil generating a targeted peak AMF amplitude along the coil axis of ∼ 100 kA/m (peak-to-peak) at a frequency of 150 kHz while maintaining field uniformity to > 90% of peak for a specified volume. This field uniformity was realized by forming the turns from cylindrical sections of copper plate and by adding flux concentrating rings to both ends of the coil. Following construction, the field profile along the axes of the coil was measured. An axial peak field value of 95.8 ± 0.4 kA/m was measured with 650 V applied to the coil and was consistent with the calculated results. The region of axial field uniformity, defined as the distance over which field ≥ 90% of peak, was also consistent with the simulated results. We describe the utility of such a device for calorimetric measurement of nanoparticle heating for cancer therapy and for magnetic fluid hyperthermia in small animal models of human cancer. © 2006 IEEE.


PubMed | Johns Hopkins University, Lambda Technologies and AMF Life Systems LLC.
Type: Journal Article | Journal: IEEE transactions on magnetics | Year: 2014

In this paper, we describe a modified solenoid coil that efficiently generates high amplitude alternating magnetic fields (AMF) having field uniformity (10%) within a 125-cm


Prevey P.S.,Lambda Technologies | Jayaraman N.,Lambda Technologies | Ravindranath R.A.,U.S. Navy | Shepard M.,U.S. Air force
Journal of Engineering for Gas Turbines and Power | Year: 2010

Low plasticity burnishing (LPB) is now established as a surface enhancement technology capable of introducing through-thickness compressive residual stresses in the edges of gas turbine engine blades and vanes to mitigate foreign object damage (FOD). The "fatigue design diagram" (FDD) method has been described and demonstrated to determine the depth and magnitude of compression required to achieve the optimum high cycle fatigue strength, and to mitigate a given depth of damage characterized by the fatigue stress concentration factor, kf. LPB surface treatment technology and the FDD method have been combined to successfully mitigate a wide variety of surface damage ranging from FOD to corrosion pits in titanium and steel gas turbine engine compressor and fan components. LPB mitigation of fretting-induced damage in Ti-6Al-4V in laboratory samples has now been extended to fan and compressor components. LPB tooling technology recently developed to allow the processing of the pressure faces of fan and compressor blade dovetails and mating disk slots is described. Fretting-induced microcracks that form at the pressure face edge of bedding on both the blade dovetail and the dovetail disk slots in Ti-6-4 compressor components can now be arrested by the introduction of deep stable compression in conventional computer numerical control (CNC) machine tools during manufacture or overhaul. The compressive residual stress field design method employing the FDD approach developed at Lambda Technologies is described in application to mitigate fretting damage. The depth and magnitude of compression and the fatigue and damage tolerance achieved are presented. It was found that microcracks as deep as 0.030 in. (0.75 mm) large enough to be readily detected by current nondestructive inspection (NDI) technology can be fully arrested by LPB. The depth of compression achieved could allow NDI screening followed by LPB processing of critical components to reliably restore fatigue performance and extend component life. Copyright © 2010 by ASME.


Hornbach D.J.,Lambda Technologies | Scheel J.E.,Lambda Technologies
ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) | Year: 2012

Stress corrosion cracking (SCC) and corrosion fatigue (CF) of 12% Cr stainless steel components can lead to reduced availability of steam turbines (ST). Significant operation and maintenance (O&M) costs are required to protect against CF and SCC in both aging and new higher efficiency ST systems. Shot peening has been used to reduce the overall operating tensile stresses, however corrosion pits, foreign object damage (FOD), and erosion can penetrate below the relatively shallow residual compression providing initiation sites for SCC and CF. A means of reliably introducing a deep layer of compressive residual stresses in critical ST components will greatly reduce O&M costs by improving CF life, increasing damage tolerance, reducing SCC susceptibility, and extending the service life of components. Low plasticity burnishing (LPB) is an advanced surface enhancement process providing a means of introducing compressive residual stresses into metallic components for enhanced fatigue, damage tolerance, and SCC performance. LPB processing can be applied as a repair process during scheduled overhauls or on new production components. High cycle fatigue tests were conducted on Type 410 stainless steel, a common alloy used in critical ST components, to compare the corrosion fatigue benefits of LPB to shot peening. Samples were tested in an active corrosion medium of 3.5% NaCl solution. Mechanical or accelerated corrosion damage was placed in test samples to simulate foreign object damage, pitting damage and water droplet erosion prior to testing. High cycle fatigue and residual stress results are shown. Compression from LPB was much deeper than the damage providing a nominal 100X improvement in fatigue life compared to the shallow compression from SP. Life extension from LPB offers significant O&M cost savings, improved reliability, and reduced outages for ST power generators. Copyright © 2012 by ASME.


Scheel J.E.,Lambda Technologies | Hornbach D.J.,Lambda Technologies
ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) | Year: 2012

Sulfide stress cracking (SSC) and hydrogen embrittlement (HE) prevent the use of high strength carbon steel alloys in the recovery of fossil fuels in H2S containing 'sour' environments commonly experienced in deep well fossil fuel recovery efforts. Couplings are a common weak point in casing strings as high magnitude mean tensile stresses are generated by connection interferences created during power make-up of downhole tubular components. When subject to service loads both mean and alternating stresses are increased further providing the high tensile stresses necessary for SSC initiation. Since high strength carbon steel alloys are not typically suited for sour service environments, the current solution is to use or develop much more expensive alloys with increased corrosion-cracking resistance, or limit their use to significantly weaker sour environments, or higher operating temperatures. Failure due to fatigue is another major problem in downhole tubular components. Likelihood of fatigue failure is further exacerbated in corrosive environments (such as H2S and NaCl), commonly encountered in service. The cost for detecting the impending failure before final separation is dramatic at a factor 10X. A cost effective method of mitigating failure from SSC and corrosion fatigue would greatly reduce operational costs and extend component life. Introduction of stable, high magnitude compressive residual stresses into less expensive carbon steel alloys alleviates the tensile stresses, and mitigates SSC, while also improving fatigue performance. Low plasticity burnishing (LPB) is an advanced surface enhancement process providing a means of introducing compressive residual stresses into metallic components for enhanced fatigue, damage tolerance, and SCC performance. The effects of LPB on high cycle fatigue (HCF) and SSC were evaluated on quench and tempered API P110 grade steel. LPB processed specimens had an increase in fatigue life greater than an order of magnitude over untreated specimens. LPB was successful in completely mitigating SSC in all test specimens at tensile stresses up to 90% specified minimum yield strength (SMYS). The initial results indicate that LPB processing of P110 steel provides an economical means of SSC mitigation and fatigue strength improvement in sour environments. Copyright © 2012 by ASME.


Hubbard R.L.,Lambda Technologies | Zappella P.,Henkel AG | Zhu P.,Henkel AG
Proceedings - Electronic Components and Technology Conference | Year: 2010

Mechanical stress in flip-chip (FC) assemblies continues to be a significant problem both for the reliability of the component and for the assembly of a flat component to the next board-level assembly. This work describes the combination of unique low-temperature multi-step curing profiles with the use of Variable Frequency Microwaves (VFM) to produce lower warpage components both on the die side of the package as well as on the board carrier side. This lower warpage compared to standard convection cure is maintained even after three sequential lead-free solder reflow conditions. Statistical data supports this increased co-planarity by Shadow Moiré measurements at various stages of processing from as-received parts through prebake, cure, and three reflow cycles. Typical co-planarity improvement in the 12 to 65 percent range is observed and verified by confirmation sample sizes used for microwave cured parts and conventional box oven cured parts. Thinned and larger die, and reduced thickness substrate boards showed the most warpage improvement with VFM. Two under-fill chemistries show the same effect despite lower cure temperatures and faster cure cycle times. A reduction of the elastic modulus above Tg was found in the VFM step-cured samples which may account for the some of the reduction in stress of the under-filled packages. © 2010 IEEE.


Hubbard R.L.,Lambda Technologies | Zappella P.,Henkel AG
IEEE Transactions on Components, Packaging and Manufacturing Technology | Year: 2011

Mechanical stress in flip-chip assemblies continues to be a significant problem both for the reliability of the component and for the assembly of a flat component to the next board-level assembly. This paper describes the combination of unique low-temperature multi-step curing profiles with the use of variable frequency microwaves (VFM) to produce lower warpage components both on the die side of the package as well as on the board carrier side. This lower warpage compared to standard convection cure is maintained even after three sequential lead-free solder reflow conditions. Statistical data support this improved co-planarity by Shadow Moiré measurements at various stages of processing from as-received parts through prebake, cure, and three reflow cycles. Typical co-planarity improvement in the 12-65 percent range is observed and verified by confirmation sample sizes used for microwave cured parts and conventional box oven cured parts. Thinned and larger die, and reduced thickness substrate boards showed the most warpage improvement with VFM. Two under-fill chemistries show the same effect despite lower cure temperatures and faster cure cycle times. © 2011 IEEE.


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