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in subjects: "Matrix Materials"

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Observation of an elementary cuboctahedron of Xe nanocrystal in an Al matrix.

When a noble gas element such as Xe is implanted in an fcc metal matrix such as Al at room temperature, a fine dispersion of precipitates forms. The precipitates are elementary fcc crystals up to diameters of several nanometers (for Xe in Al, 8-10 rim), above which they are non-crystalline. The precipitates exhibit a cube-on-cube orientation relation with the matrices and have lattice parameters which are much larger than those of the matrices (a{sub Xe} = 1.5a{sub Al}). Thus the interphase int… more

Date: March 10, 1999

Creator: Allen, C. W.; Birtcher, R. C.; Donnelly, S. E.; Furuya, K.; Ryan, E. A. & Song, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Deformation texture development in a model composite system

Model composites fabricated with a polycrystalline copper matrix and continuous tungsten fibres were deformed in plane strain compression with the fibres perpendicular to the loading axis and parallel to the direction of zero strain. The development of texture in the matrix due to deformation was measured using x-ray diffraction. It was observed that the macroscopic texture development in the composite was weaker than for unreinforced copper. The pattern of deformation in the matrix was quantif… more

Date: May 1, 1995

Creator: Poole, W. J.; MacEwen, S.; Kocks, U. F. & Embury, J. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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A cell model for homogenization of fiber-reinforced composites: General theory and nonlinear elasticity effects

The theoretical basis of the homogenization technique developed by Aboudi is presented and assessed. Given the constitutive relations of the constituents, this technique provides an equivalent, homogeneous, constitutive model of unidirectional, continuous-fiber-reinforced composites. The expressions that comprise the first-order version of the technique are given special attention as this treatment has considerable practical value. Nonlinear elasticity effects are added to it. This extension in… more

Date: November 1, 1995

Creator: Aidun, J.B. & Addessio, F.L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Development and compatibility of magnesium matrix fuel plates clad with 6061 aluminum alloy.

Aluminum (Al) is a commonly used matrix for research reactor fuel plates. It has been found that a reaction between the fuel and the aluminum matrix may reduce or increase the irradiation stability of the fuel. To further understand the contribution of the reaction to the irradiation stability, experiments to develop a non-reacting matrix were performed. The work focused on magnesium (Mg), which is an excellent non-reacting matrix candidate and has a neutron absorption coefficient similar to Al… more

Date: October 22, 1998

Creator: Wiencek, T. C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Mechanical properties and failure mechanisms of carbon fiber reinforced epoxy laminated composites

The mechanical behavior of quasi-isotropic and unidirectional epoxy-matrix carbon-fiber laminated composites subjected compressive loading at strain rates of 10{sup {minus}3} and 2000 s{sup {minus}1} are described. Failure in the studied composites was dominated by delamination which proceeded by brittle fracture of the epoxy-matrix. The matrix-fiber bonding in these composites is very strong and prevented the occurrence of significant fiber-pullout. The mode I delamination strain energy releas… more

Date: September 1, 1995

Creator: Thissell, W.R.; Zurek, A.K. & Addessio, F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Development of metal hydride composites

Most of current hydride technology at Savannah River Site is based on beds of metal hydride powders; the expansion upon hydridation and the cycling results in continued breakdown into finer particles. Goal is to develop a composite which will contain the fines in a dimensionally stable matrix, for use in processes which require a stable gas flow through a hydride bed. Metal hydride composites would benefit the advanced Thermal Cycling Absorption process (hydrogen isotope separation), and the Re… more

Date: December 1, 1992

Creator: Congdon, J. W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Novel oxide-oxide fiber reinforced hot gas filter development

The objective of this program is to fabricate and test oxide fiber reinforced composite hot gas filter elements for advanced power generation systems. The level of mechanical durability exhibited by the currently available filters in field tests indicates that more rugged filters are required to meet the demands of large power generation systems. Furthermore, long term corrosion resistance of currently available filters has yet to be demonstrated in PFBC systems. The essential requirements of a… more

Date: December 1, 1995

Creator: Wagner, R. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Microstructure and Phase Development of Buried Resistors in Low Temperature Co-Fired Ceramic

Embedded resistor circuits have been generated with the use of a Micropen system Ag conductor paste (DuPont 6142D), a new experimental resistor ink from DuPont (E84005-140), and Low Temperature Co-fired Ceramic (LTCC) green tape (DuPont A951). Sample circuits were processed under varying peak temperature ranges (835 C-875 C) and peak soak times (10 min-720 min). Resistors were characterized by SEM, TEM, EDS, and high-temperature XRD. Results indicate that devitrification of resistor glass phase… more

Date: November 30, 1999

Creator: Dimos, Duane B.; Kotula, Paul G.; Rodriguez, Mark A. & Yang, Pin

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Final report for the ORNL/3M CRADA No. ORNL91-0061 for the period January 1, 1992--December 31, 1992

Oxide fiber-reinforced silicon carbide matrix composites were fabricated employing the forced-flow, thermal gradient chemical vapor infiltration (FCVI) process. Composites using Nextel{trademark} fibers of varying composition were prepared to investigate the effectiveness of each Nextel{trademark} fiber as a reinforcement for the given matrix. A carbon interface coating was used for the baseline materials, however, alternate interlayers with improved oxidation resistance were also explored. Roo… more

Date: October 1, 1995

Creator: Weaver, B.L.; Besmann, T.M. & Lowden, R.A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Criteria for progressive interfacial debonding with friction in fiber-reinforced ceramic composites

Criteria for progressive debonding at the fiber/matrix interface with friction along the debonded interface are considered for fiber-reinforced ceramic composites. The energy-based criterion is adopted to analyze the debond length, the crack-opening displacement, and the displacement of the composite due to interfacial debonding. The analytical solutions are identical to those obtained from the mismatch-strain criterion, in which interfacial debonding is assumed to occur when the mismatch in th… more

Date: December 31, 1995

Creator: Hsueh, C.H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Composite heat damage assessment

The effects of heat damage were determined on the residual mechanical, physical, and chemical properties of IM6/3501-6 laminates, and potential nondestructive techniques to detect and assess material heat damage were evaluated. About one thousand preconditioned specimens were exposed to elevated temperatures, then cooled to room temperature and tested in compression, flexure, interlaminar shear, shore-D hardness, weight loss, and change in thickness. Specimens experienced significant and irreve… more

Date: December 31, 1993

Creator: Janke, C. J.; Wachter, E. A.; Philpot, H. E. & Powell, G. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Using transverse isotropy to model arbitrary deformation-induced anisotropy

A unifying framework is developed for the analysis of brittle materials. Heretofore diverse classes of models result from different choices for unspecified coefficient and distribution functions in the unified theory. Material response is described in terms of expectation integrals of transverse symmetry tensors. First, a canonical body containing cracks of all the same orientation is argued to possess macroscopic transverse isotropy. An orthogonal basis for the linear subspace consisting of al… more

Date: July 1, 1996

Creator: Brannon, R.M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Functionally Gradient Materials for Thermal Barrier Coatings in Advanced Gas Turbine Systems

New designs for advanced gas turbine engines for power production are required to have higher operating temperatures in order to increase efficiency. However, elevated temperatures will increase the magnitude and severity of environmental degradation of critical turbine components (e.g. combustor parts, turbine blades, etc.). To offset this problem, the usage of thermal barrier coatings (TBCs) has become popular by allowing an increase in maximum inlet temperatures for an operating engine. Alth… more

Date: December 31, 1995

Creator: Banovic, Stephen W.; Chan, Helen M.; Marder, Arnold R.; Puerta, Douglas G.; Barmak, Katayun; Harmer, Martin P. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Environmental aging degradation in continuous fiber ceramic composites

The thermal stability of two-continuous fiber ceramic composites (CFCC`s) has been assessed. A Nicalon/CaO-Al{sub 2}O{sub 3}-SiO{sub 2} (CAS) glass-ceramic composite has been subjected to unstressed, oxidation heat treatments between 375 and 1200{degrees}C, after which the material was tested in flexure at room temperature. The static fatigue behavior of a chemical vapor infiltrated (CVI) Nicalon/SiC ceramic matrix composite has been assessed in air, between 425 and 1150{degrees}C, both with an… more

Date: December 31, 1995

Creator: Plucknett, K. P.; Lin, H. T.; Braski, D. N. & Becher, P. F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Carbonate fuel cell matrix strengthening

The present baseline electrolyte matrix is a porous ceramic powder bed impregnated with alkali carbonate electrolyte. The matrix provides both ionic conduction and gas sealing. During fuel cell stack operation, the matrix experiences both mechanical and thermal stresses. Different mechanical characteristics of active and wet seal areas generate stress. Thermal stress is generated by nonuniform temperature distribution and thermal cycling. A carbonate fuel cell generally may experience planned a… more

Date: December 31, 1995

Creator: Yuh, C. Y.; Haung, C. M. & Johnsen, R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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NO decomposition in non-reducing atmospheres. Technical progress report, June 1995--August 1995

Samples of Mn(II) Nafion, MN(II)-A zeolite, and various Co(II)-ZSM-5 zeolites were prepared by aqueous ion exchange techniques. Co(II)- and Mn(II)-containing ZSM-5, erionite, and mordenite were obtained from other sources. Co(II)-containing samples were studied by diffuse reflectance spectroscopy in the dehydrated state and after exposure to NO atmosphere. In addition, the magnetic susceptibilities of these samples were determined. It was shown that two NO molecules were adsorbed onto each Co(I… more

Date: September 1, 1995

Creator: Klier, Kamil; Herman, Richard G. & Dědeček, Jiří

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Potential benefits and impacts on the CRWMS transportation system of filling spent fuel shipping casks with depleted uranium silicate glass

A new technology, the Depleted Uranium Silicate COntainer Fill System (DUSCOFS), is proposed to improve the performance and reduce the uncertainties of geological disposal of spent nuclear fuel (SNF), thus reducing both radionuclide release rates from the waste package and the potential for repository nuclear criticality events. DUSCOFS may also provide benefits for SNF storage and transport if it is loaded into the container early in the waste management cycle. Assessments have been made of th… more

Date: June 1, 1996

Creator: Pope, R. B.; Forsberg, C. W.; DeHart, M. D.; Childs, K. W. & Tang, J. S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Cure shrinkage effects in epoxy and polycyanate matrix composites

A relatively new advanced composite matrix, polycyanate ester, was evaluated for cure shrinkage. The chemical cure shrinkage of composites is difficult to model but a number of clever experimental techniques are available to the investigator. In this work the method of curing a prepreg layup on top of a previously cured laminate of identical ply composition is utilized. The polymeric matrices used in advanced composites have been primarily epoxies and therefore a common system of this type, Fib… more

Date: December 22, 1995

Creator: Spellman, Gordon P.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Interface degradation in CAS/Nicalon during elevated temperature aging

A CaO-Al{sub 2}O{sub 3}-SiO{sub 2} (CAS)/Nicalon glass-ceramic matrix composite has been subjected to elevated temperature oxidation heat-treatments between 375 and 1200{degrees}C, for up to 100 hours. Micro- and macro-mechanical properties have been determined by fiber push-down, using a mechanical properties microprobe, and flexure testing, respectively. Aging between 450 and 800{degrees}C results in significant property degradation, with reduced bending modulus and flexure strength, increase… more

Date: March 1, 1995

Creator: Plucknett, Kevin P.; Cain, Rebecca L. & Lewis, M. H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Determination of fission neutron transmission through waste matrix material using neutron signal correlation from active assay of {sup 239}Pu

The accuracy of TRU (transuranic) waste assay using the differential die-away technique depends upon significant corrections to compensate for the effects of the matrix material in which the TRU waste is located. The authors have used a new instrument, the Combined Thermal/Epithermal Neutron (CTEN) instrument for the assay of TRU waste, to develop methods to improve the accuracy of these corrections. Neutrons from a pulsed 14-MeV neutron generator are moderated in the walls of the CTEN cavity a… more

Date: September 1, 1996

Creator: Hollas, C.L.; Arnone, G.; Brunson, G. & Coop, K.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Results from the first Waste and Residue NDA Measurements School

The first Waste and Residue Nondestructive Assay (NDA) Measurements School was given at Los Alamos on June 3--7, 1996. This school is a new part of the DOE Office of Safeguards and Security, Safeguards Training Program, with additional instructor support from the National Transuranic Waste Program, Idaho National Engineering Laboratory, Oak Ridge National Laboratory, Portsmouth Gaseous Diffusion Plant, Westinghouse savannah River Company, Pajarito Scientific Corporation, and Canberra Industries… more

Date: September 1, 1996

Creator: Ensslin, N.; Abhold, M.; Coop, K.; Prettyman, T.; Rinard, P.; Sheppard, G. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Implementation of advanced matrix corrections for active interrogation of waste drums using the CTEN instrument

The combined thermal/epithermal neutron instrument (CTEN) was designed at Los Alamos to improve measurement accuracy and mitigate self shielding effects inherent in the differential dieaway technique (DDT). A major goal in this research effort has been the development of a calibration technique that incorporates recently developed matrix and self-shielding corrections using data generated from additional detectors and new acquisition techniques. A comprehensive data set containing both active a… more

Date: December 31, 1998

Creator: Melton, S.; Estep, R. & Hollas, C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The effects of surface modification on the speciation of metal ions intercalated into aluminosilicates

Microporous aluminosilicates, including clay minerals and zeolites, are ion-exchange materials. In their most common forms, they have the ability to incorporate cationic species within their matrices. Because of this property, microporous aluminosilicates have been proposed as storage media for hazardous waste. In this paper the authors use X-ray absorption spectroscopy (XAS) to examine the structure of cations held within smectite clay minerals and to determine how modification of the surface … more

Date: December 31, 1996

Creator: Wasserman, S.R.; Giaquinta, D.M.; Yuchs, S.E. & Soderholm, L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Approach to inherently stable interfaces for ceramic matrix composites

Virtually all ceramic matrix composites require and interface coating between the fibers and matrix to achieve the desired mechanical performance. To date, the most effective interface materials for non- oxide matrix composites have been carbon and boron nitride. They are, however, susceptible to oxidation at elevated temperatures, and thus under many envisioned operating environments they will fail, possibly allowing oxidation of the fibers as well, adversely affecting mechanical behavior. Cur… more

Date: September 1, 1996

Creator: Besmann, T.M.; Kupp, E.R.; Stinton, D.P. & Shanmugham, S.

Item Type: Article

Partner: UNT Libraries Government Documents Department