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CRT compatibility evaluation of LX-16 and Halthane 73-18

Description: A preliminary compatibility study was carried out between the plastic-bonded PETN-based high explosive LX-16 and the adhesive Halthane 73-18. The work, based on the Chemical Reactivity Test (CRT), used non-standard times and temperatures to find conditions corresponding to accelerated decomposition. This study is a prequel to a more comprehensive isothermal and thermal cycling study that will include both material evaluation and test fire.
Date: August 24, 1999
Creator: Foltz, M F; Reyes, P & Foster, P A
Partner: UNT Libraries Government Documents Department

CRT compatibility evaluation of LX-16 and Halthane 73-18

Description: A preliminary compatibility study was carried out between the plastic-bonded PETN- based high explosive LX-16 and the adhesive Halthane 73-l 8. The work, based on the Chemical Reactivity Test (CRT), used non-standard times and temperatures to find conditions corresponding to accelerated decomposition. This study is a prequel to a more comprehensive isothermal and thermal cycling study that will include both material evaluation and test tire.
Date: March 26, 1999
Creator: Foltz, M F & Foster, P A
Partner: UNT Libraries Government Documents Department

Rapid thermal cycling of metal-supported solid oxide fuel cellmembranes

Description: Solid oxide fuel cell (SOFC) membranes were developed in which zirconia-based electrolyte thin films were supported by a composite metal/ceramic electrode, and were subjected to rapid thermal cycling between 200 and 800 C. The effects of this cycling on membrane performance were evaluated. The membranes, not yet optimized for performance, showed a peak power density of 350mW/cm2at 900 C in laboratory-sized SOFCs that was not affected by the thermal cycling. This resistance to cycling degradation is attributed to the close matching of thermal expansion coefficient of the cermet support electrode with that of the zirconia electrolyte.
Date: January 2, 2004
Creator: Matus, Yuriy B.; De Jonghe, Lutgard C.; Jacobson, Craig P. & Visco, Steven J.
Partner: UNT Libraries Government Documents Department

Reliability Testing the Die-Attach of CPV Cell Assemblies

Description: Results and progress are reported for a course of work to establish an efficient reliability test for the die-attach of CPV cell assemblies. Test vehicle design consists of a ~1 cm2 multijunction cell attached to a substrate via several processes. A thermal cycling sequence is developed in a test-to-failure protocol. Methods of detecting a failed or failing joint are prerequisite for this work; therefore both in-situ and non-destructive methods, including infrared imaging techniques, are being explored as a method to quickly detect non-ideal or failing bonds.
Date: February 1, 2011
Creator: Bosco, N.; Sweet, C. & Kurtz, S.
Partner: UNT Libraries Government Documents Department

Burst Martensitic Transformations in a Steel and in a Pu-Ga Alloy

Description: Upon cooling a Pu-2.0 at% Ga alloy from the ambient temperature, the metastable delta phase partially transforms martensitically to the alpha-prime phase. Because this transformation involves a 25% volume contraction, plastic accommodation by the delta matrix must occur. When the material is isochronally heated or isothermally annealed above ambient temperatures, the reversion of alpha-prime to delta is likely to occur by the alpha-prime/delta interface moving to consume the alpha-prime particles. This reversion exhibits a burst martensitic mode and is observed as sharp spikes in differential scanning calorimetry data and as steps in resistometry data. These large bursts appear to be the result of an interplay between the autocatalytically driven transformation of individual alpha-prime particles and self-quenching caused by small changes in temperature and/or stress accompanying each burst. The behavior of this Pu-Ga alloy is compared to that of a steel referred to as a ''burst martensite'' in the literature, which also exhibits bursts during both thermal cycling and isothermal holds.
Date: June 14, 2005
Creator: Blobaum, K; Krenn, C; Wall, M & Schwartz, A
Partner: UNT Libraries Government Documents Department

Packaging strategies for printed circuit board components. Volume I, materials & thermal stresses.

Description: Decisions on material selections for electronics packaging can be quite complicated by the need to balance the criteria to withstand severe impacts yet survive deep thermal cycles intact. Many times, material choices are based on historical precedence perhaps ignorant of whether those initial choices were carefully investigated or whether the requirements on the new component match those of previous units. The goal of this program focuses on developing both increased intuition for generic packaging guidelines and computational methodologies for optimizing packaging in specific components. Initial efforts centered on characterization of classes of materials common to packaging strategies and computational analyses of stresses generated during thermal cycling to identify strengths and weaknesses of various material choices. Future studies will analyze the same example problems incorporating the effects of curing stresses as needed and analyzing dynamic loadings to compare trends with the quasi-static conclusions.
Date: September 1, 2011
Creator: Neilsen, Michael K. (Kansas City Plant, Kansas City, MO); Austin, Kevin N.; Adolf, Douglas Brian; Spangler, Scott W.; Neidigk, Matthew Aaron & Chambers, Robert S.
Partner: UNT Libraries Government Documents Department

Modeling phase transformation behavior during thermal cycling in the heat-affected zone of stainless steel welds

Description: An implicit finite-difference analysis was used to model the diffusion-controlled transformation behavior in a ternary system. The present analysis extends earlier work by examining the transformation behavior under the influence of multiple thermal cycles. The analysis was applied to the Fe-Cr-Ni ternary system to simulate the microstructural development in austenitic stainless steel welds. The ferrite-to-austenite transformation was studied in an effort to model the response of the heat-affected zone to multiple thermal cycles experienced during multipass welding. Results show that under some conditions, a transformation ``inertia`` exists that delays the system`s response when changing from cooling to heating. Conditions under which this ``inertia`` is most influential were examined. It was also found that under some conditions, the transformation behavior does not follow the equilibrium behavior as a function of temperature. Results also provide some insight into effect of composition distribution on transformation behavior.
Date: December 31, 1995
Creator: Vitek, J.M.; Iskander, Y.S. & David, S.A.
Partner: UNT Libraries Government Documents Department

Modeling non-isothermal intermetallic layer growth in the 63Sn-37Pb/Cu system

Description: A model describing diffusion-controlled growth of multiple intermetallic layers and the displacement of the interfaces between layers was developed and implemented in a 1-D computer code based on method-of-lines. The code was applied to analysis of intermetallic layer growth in isothermal solder aging experiments performed with 100 Sn/Cu and 63Sn-37Pb/Cu solder-substrate systems. Analyses indicated that intermetallic layer growth was consistent with a bulk diffusion mechanism involving Cu and/or Sn. In this work, nonisothermal solder-aging experiments were done with the 63Sn- 37Pb/Cu system using two temperature histories (4 cycles/day between 223-443 K, and 72 cycles/day between 223-443 K). Isothermal experiments were also done at 443 K. Thickness of Cu{sub 3}Sn and Cu{sub 6}Sn{sub 5} intermetallic layers were determined vs time for each temperature history. An updated version of the model and code were used to predict the intermetallic layer growth. Arrhenius expressions for diffusion coefficients in both Cu3Sn and Cu6Sn5 layers were determined. Agreement between prediction and experiment was generally good. In some cases, predicted layer growth was less than experiment, but within error. This paper describes the nonisothermal experiments and a comparison of predicted and observed layer growth vs time.
Date: December 31, 1996
Creator: Vianco, P.T.; Hopkins, P.L.; Erickson, K.L.; Frear, D.R. & Davidson, R.
Partner: UNT Libraries Government Documents Department

In situ study of dislocation behavior in columnar Al thin film on Si substrate during thermal cycling

Description: In situ transmission electron microscopy (150 kV) has been employed to study the evolution of dislocation microstructure during relatively rapid thermal cycling of a 200 nm Al thin film on Si substrate. After a few thermal cycles between 150 and 500 C, nearly stable Al columnar grain structure is established with average grain less than a {micro}m. On rapid cooling (3--30+ C/s) from 500 C, dislocations first appear at a nominal temperature of 360--380 C, quickly multiplying and forming planar glide plane arrays on further cooling. From a large number of such experiments the authors have attempted to deduce the dislocation evolution during thermal cycling in these polycrystalline Al films and to account qualitatively for the results on a simple dislocation model.
Date: December 13, 1999
Creator: Allen, C. W.; Schroeder, H. & Hiller, J. M.
Partner: UNT Libraries Government Documents Department

Transformation kinetics in controlled-power and controlled-temperature cycle testing

Description: On-heating transformation kinetics were investigated for several steels by using a Gleeble capable of programmable power input as well as programmable temperature cycling. Transformation kinetics determined in both modes are reported. The temperature cycles are significantly different between the two modes due to the latent heat associated with the phase transformations. Both diffusion rates and transformation driving force increase with temperature above the eutectoid temperature, therefore the latent heat can potentially have a significant impact on the transformation kinetics. Experiments with plain carbon steels illustrate that the latent heat of austenite formation causes an appreciable temperature arrest during transformation, and the dilatation response is similarly altered. A kinetic transformation model, based on the decomposition of pearlite and the diffusional growth of austenite, reproduced the transient dilatation data obtained from both control modes reasonably well using the same kinetic parameter values.
Date: June 1, 1998
Creator: Robino, C.V.; Knorovsky, G.; Dykhuizen, R.C.; MacCallum, D.O. & Damkroger, B.K.
Partner: UNT Libraries Government Documents Department

Plasma synthesis of high temperature ceramic films

Description: Thin films of alumina, chromia, mullite, yttria and zirconia have been synthesized using a plasma-based method called metal plasma immersion ion implantation and deposition (Mepiiid)--a highly versatile plasma deposition technique with ion energy control. Monolithic films (a single ceramic component) and multilayer films (individual layers of different ceramic materials) were formed. The films were characterized for their composition and structure in a number of different ways, and the high temperature performance of the films was explored, particularly for their ability to maintain their integrity and adhesion when subjected to repetitive high temperature thermal cycling up 1100 C. We found that the films retain their adhesion and quality without any apparent degradation with time, even after a large number of cycles; (the tests were extended out to a total of 40 cycles each of 24 hours duration). After repetitive high temperature thermal cycling, the film-substrate adhesion was greater than {approx}70 Mpa, the instrumental limit of measurement, and the interface toughness was approximately 0.8 MPa m{sup 1/2}.
Date: November 1, 1998
Creator: Brown, I.G. & Monteiro, O.R.
Partner: UNT Libraries Government Documents Department

Stability of Tl-Ba-Ca-Cu-O Superconducting Thin Films

Description: We report the stability of TlBa{sub 2}CaCu{sub 2}O{sub 7} (Tl-1212) and Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8} (T1-2212) thin films and by inference, the stability of TlBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub 9} (Tl-1223) and Tl{sub 2}Ba{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10} (Tl-2223) thin films, under a variety of conditions. In general, we observe that the stability behavior of the single Tl-O layer materials (Tl-1212 and Tl-1223)are similar and the double Tl-O layer materials (Tl-2212 and Tl-2223) are similar. All films are stable with repeated thermal cycling to cryogenic temperatures. Films are also stable in acetone and methanol. Moisture degrades film quality rapidly, especially in the form of vapor. Tl-1212 is more sensitive to vapor than Tl-2212. These materials are stable to high temperatures in either N{sub 2}, similar to vacuum for the cuprates, and O{sub 2} ambients. While total degradation of properties (superconducting and structural) occur at the same temperatures for all phases, 600 C in N{sub 2} and 700 C in O{sub 2}, the onset of degradation occurs at somewhat lower temperatures for Tl-1212 than for Tl-2212 films. In all cases, sample degradation is associated with Tl depletion from the films.
Date: August 23, 1999
Creator: Siegal, M.P.; Overmyer, D.L.; Venturini, E.L.; Padilla, R.R. & Provencio, P.N.
Partner: UNT Libraries Government Documents Department

Thermal cycle test for invar pipe with fixed ends and many welds

Description: This report discusses some work which was done to help insure the wisdom of using an invar ( 36 % Ni steel) cold tube as the vacuum containment for a transmission line type conductor for magnetizing warm iron for a very large hadron collider. The advantages of invar are that it has a very low coefficient of thermal expansion. The expansion is so low that the transmission line can be built without the use of bellows or other flexible sections, which would result in lower cost and increased reliability. The goal is to test whether the invar pipe can undergo many thermal cycles from 300 K to saturated liquid nitrogen temperature while the ends of the pipe are held fixed. A secondary goal is determine the cryogenic reliability of a large sample of invar welds. Ideally, the strain induced in the invar during a cool down is independent of the total length of the pipe. In a world with errors, such as bending of supports, one gets a more accurate test by using a long pipe. The use of a long pipe reduces the importance of end effects, where the undesirable bending occurs.
Date: December 1, 1998
Creator: Moreland, G.W. Foster and Tom & Walker, R.J.
Partner: UNT Libraries Government Documents Department

Damage evolution and residual stresses in plasma-sprayed zirconia thermal barrier coatings.

Description: Air-plasma-sprayed zirconia thermal barrier coatings were subjected to thermal cycling and residual stress evolution in thermally grown oxide scale was studied by micro- and macro-ruby fluorescence spectroscopy. The macro approach reveals that compressive stress in the oxide scale increases with increasing number of thermal cycles (and thus increasing scale thickness), reaching a value of 1.8 GPa at a scale thickness of 3-4 {micro}m (80 cycles). Micro-ruby fluorescence spectroscopy indicates that protrusions of the zirconia top coat into the bond coat act as localized areas of high stress concentration, leading to damage initiation during thermal cycling.
Date: February 3, 1999
Creator: Singh, J. P.
Partner: UNT Libraries Government Documents Department

Measurement of Thermal Diffusity and Flow Resistance for TCAP Materials

Description: SRS uses the Thermal Cycling Absorption Process (TCAP) to separate isotopes of hydrogen. The frequency of thermal cycles is a limit of the productivity of the process and that frequency is largely determined by the thermal diffusivity of the absorbent material. For a given tube diameter, a larger thermal diffusivity decreases the time required for each cycle. In 1998, the Engineering Development Laboratory measured thermal diffusivity and thermal conductivity for three TCAP materials in helium.
Date: November 11, 2004
Creator: Steimke, John
Partner: UNT Libraries Government Documents Department


Description: This report summarizes the work performed for April 2003--September 2003 reporting period under Cooperative Agreement DE-FC26-01NT41245 for the U.S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Solid State Energy Conversion Alliance (SECA) Solid oxide Fuel Cell Program''. During this reporting period, the conceptual system design activity was completed. The system design, including strategies for startup, normal operation and shutdown, was defined. Sealant and stack materials for the solid oxide fuel cell (SOFC) stack were identified which are capable of meeting the thermal cycling and degradation requirements. A cell module was tested which achieved a stable performance of 0.238 W/cm{sup 2} at 95% fuel utilization. The external fuel processor design was completed and fabrication begun. Several other advances were made on various aspects of the SOFC system, which are detailed in this report.
Date: October 1, 2003
Creator: Minh, Nguyen & Powers, Jim
Partner: UNT Libraries Government Documents Department

Long-Term Cyclic Oxidation Behavior of Wrought Commercial Alloys at High Temperatures

Description: The oxidation resistance of a high-temperature alloy is dependent upon sustaining the formation of a protective scale, which is strongly related to the alloying composition and the oxidation condition. The protective oxide scale only provides a finite period of oxidation resistance owing to its eventual breakdown, which is especially accelerated under thermal cycling conditions. This current study focuses on the long-term cyclic oxidation behavior of a number of commercial wrought alloys. The alloys studied were Fe- and Ni-based, containing different levels of minor elements, such as Si, Al, Mn, and Ti. Oxidation testing was conducted at 1000 and 1100 C in still air under both isothermal and thermal cycling conditions (1-day and 7-days). The specific aspects studied were the oxidation behavior of chromia-forming alloys that are used extensively in industry. The current study analyzed the effects of alloying elements, especially the effect of minor element Si, on cyclic oxidation resistance. The behavior of oxide scale growth, scale spallation, subsurface changes, and chromium interdiffusion in the alloy were analyzed in detail. A novel model was developed in the current study to predict the life-time during cyclic oxidation by simulating oxidation kinetics and chromium interdiffusion in the subsurface of chromia-forming alloys.
Date: August 5, 2003
Creator: Li, Bingtao
Partner: UNT Libraries Government Documents Department


Description: A change in field harmonics after quench and thermal cycles has been observed in superconducting magnets for the Relativistic Heavy Ion Collider (RHIC). This paper presents the results of a systematic investigation of this effect in a number of RHIC dipole and quadrupole magnets. These changes in field harmonics may limit the ultimate field quality and its reproducibility in superconducting magnets. A change in pre-stress has also been observed after quench and thermal cycles. A possible link between these two changes is explored.
Date: May 12, 1997
Partner: UNT Libraries Government Documents Department

Final Report for the PolyHANAA

Description: The PolyHanaa is a 24 chamber thermal cycling instrument designed to perform rapid, real-time optical detection of biological agents using the Polymerase Chain Reaction (PCR) process with TaqMan{trademark} reagents. Liquid samples are pipetted into small, disposable polypropylene tubes that are then inserted into the chambers. The 24 duplex chambers are divided into 6 independent groups and run information is presented simultaneously, in real time, for all groups.
Date: April 30, 2001
Creator: Richards, J. B.; Stratton, P. L.; Benett, W. J.; Koopman, R. P. & Milanovich, F. P.
Partner: UNT Libraries Government Documents Department


Description: This report details the efforts by engineers at the National Synchrotron Light Source (NSLS) of Brookhaven National Laboratory (BNL) to evaluate the reliability of water-cooled radiation absorbers used in the NSLS X-ray ring. These absorbers are part of the 16 dipole vacuum chambers which comprise the arc sections of the ring. They are located at the intersections (crotch) of the beamline exit ports with the electron beam chamber, and are commonly referred to as "crotches". The purpose of these efforts was to demonstrate the reliability of the crotches under operating conditions that the crotches will be subjected to over the entire expected life of the ring. The efforts described include engineering calculations, finite element analysis, conceptual design for a reliability test, test implementation and descriptions, results and conclusions related to these analyses and tests.
Date: April 9, 1999
Creator: Lynch, D. R.
Partner: UNT Libraries Government Documents Department

NREL PV Module Reliability and Performance R&D Status and Accomplishments

Description: This paper presents a brief overview of the status and accomplishments during Fiscal Year (FY)2004 of the Photovoltaic (PV) Module Reliability and Performance R&D Subtask, which is part of the PV Module Reliability R&D Project (a joint NREL-Sandia project).
Date: January 1, 2005
Creator: Osterwald, C. R.
Partner: UNT Libraries Government Documents Department