18 Matching Results

Search Results

Results: 1 - 18
open access

Specimen Size Effect on the Creep of Si3N4

Description: The effect of specimen size on the measured tensile creep behavior of a commercially available gas pressure sintered Si3N4 was examined. Button-head tensile test specimens were used for the testing, and were machined to a variety of different gage section diameters (ranging from 2.5 to 6.35 mm) or different surface-area-to-volume ratios. The specimens were then creep tested at 1350 Degrees C and 200 MPa with tensile creep strain continuously measured as a function of time. The steady-state cree… more
Date: January 25, 1999
Creator: Barnes, A. S.; Ferber, M. K.; Kirkland, T. P. & Wereszczak, A. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Prediction of the Inert Strength Distribution of Si3N4 Diesel Valves

Description: Censored Weibull strength distributions were generated with NT551 silicon nitride four-point flexure data using the ASTM C1161-B and 5.0 mm diameter cylindrical specimens. Utilizing finite element models and AlliedSignal's life prediction codes, the inert or fast fracture strength failure probability of a ceramic diesel valve was estimated from these data sets. The failure probability prediction derived from each data set were found to be more conservative than valve strength data. Fractographi… more
Date: January 25, 1999
Creator: Andrews, M. J.; Breder, K. & Wereszczak, A. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Corrective Action Investigation Plan for Corrective Action Unit 240: Area 25 Vehicle Washdown Nevada Test Site, Nevada

Description: This Corrective Action Investigation Plan (CAIP) has been developed in accordance with the Federal Facility Agreement and Consent Order (FFACO) that was agreed to by the US Department of Energy, Nevada Operations Office (DOE/NV); the State of Nevada Division of Environmental Protection (NDEP); and the US Department of Defense (FFACO, 1996). The CAIP is a document that provides or references all of the specific information for investigation activities associated with Corrective Action Units (CAU… more
Date: January 25, 1999
Creator: DOE/NV
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

An Investigation of Cross-Borehole Ground Penetrating Radar Measurements for Characterizing the 2D Moisture Content Distribution in the Vadose Zone

Description: The use of cross-borehole ground penetrating radar (GPR) imaging for determining g the two dimensional (2D) in situ moisture content distribution within the vadose zone is being investigated. The ultimate goal is to use the GPR images as input to a 2D hydrologic inversion scheme for recovering the van Genuchten parameters governing unsaturated ,hydraulic flow. Initial experiments conducted on synthetic data have shown that at least in theory, cross-borehole GPR measurements can provide realisti… more
Date: January 25, 1999
Creator: Alumbaugh, D. & Paprocki, L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Understanding and Tailoring the Mechanical Properties of LIGA Fabricated Materials

Description: LIGA fabricated materials and components exhibit several processing issues affecting their metallurgical and mechanical properties, potentially limiting their usefulness for MEMS applications. For example, LIGA processing by metal electrodeposition is very sensitive to deposition conditions which causes significant processing lot variations of mechanical and metallurgical properties. Furthermore, the process produces a material with a highly textured lenticular rnicrostructural morphology sugge… more
Date: January 25, 1999
Creator: Buchheit, T.E.; Christenson, T.R.; Lavan, D.A. & Schmale, D.T.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Microseismic Monitoring of the Mounds Drill Cuttings Injection Tests

Description: This paper describes the microseismic mapping of repeated injections of drill cuttings into two separate formations at a test site near Mounds, OK. Injections were performed in sandstone and shale formations at depths of 830 and 595 m, respectively. Typical injection disposal was simulated using multiple small-volume injections over a three-day period, with long shut-in periods interspersed between the injections. Microseismic monitoring was achieved using a 5-level array of wireline-run, triax… more
Date: January 25, 1999
Creator: Branagan, P. T.; Mahrer, K. D.; Moschovidis, Z. A.; Warpinski, N. R. & Wolhart, S. L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Optical Properties of InGaAsN: A New 1eV Bandgap Material System

Description: InGaAsN is a new semiconductor alloy system with the remarkable property that the inclusion of only 2% nitrogen reduces the bandgap by more than 30%. In order to help understand the physical origin of this extreme deviation from the typically observed nearly linear dependence of alloy properties on concentration, we have investigated the pressure dependence of the excited state energies using both experimental and theoretical methods. We report measurements of the low temperature photohnninesce… more
Date: January 25, 1999
Creator: Allerman, A. A.; Fritz, I. J.; Jones, E. D.; Kurtz, S. R.; Modine, N. A.; Tozer, S. T. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Effects of Particulate Debris Morphology on the Rolling Wear Behavior of All-Steel and Si(Sub 3)N(Sub 4)-Steel Bearing Element Couples

Description: Rolling contact fatigue experiments were performed on all-steel and hybrid Si{sub 3}N{sub 4}-M50 steel rolling bearing systems using particulate contaminated lubricants. The particulate contaminants used were glycothermally synthesized {alpha}-Al{sub 2}O{sub 3} platelets or Arizona test dust. The effects of contaminant composition and morphology on rolling contact fatigue and wear behavior were explored. The effects of bearing element material properties on fatigue and wear behavior were also e… more
Date: January 25, 1999
Creator: Adair, J.H.; Mecholsky, J.J., Jr. & Mitchell, D.J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Determination of Strength for Reliability Analysis of Multilayer Ceramic Capacitors

Description: A Nanoindenter<sup>TM</sup> equipped with a Vickers indenter was used to measure fracture toughness of Multilayer Capacitors (MLCs) and BaTiO<sub>3</sub> blanks. Strength of blanks of 6.3 x 4.7 x 1.1 mm<sup>3</sup> was measured by performing three-point flexure using a 4 mm support span. The size of the strength limiting pores in the flexure tests was compared to pore sizes measured on polished MLC cross sections, and it was found that much larger pores were present in the 3-point flexure speci… more
Date: January 25, 1999
Creator: Breder, K.; Bridge, R. J.; Kirkland, T. P.; Riester, L. & Wereszczak, A. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Immobilization of excess weapons plutonium in Russia

Description: In this paper, we examine the logic and framework for the development of a capability to immobilize excess Russian weapons plutonium by the year 2004. The initial activities underway in Russia, summarized here, include engineering feasibility studies of the immobilization of plutonium-containing materials at the Krasnoyarsk and Mayak industrial sites. In addition, research and development (R&D) studies are underway at Russian institutes to develop glass and ceramic forms suitable for the immobi… more
Date: January 25, 1999
Creator: Borisov, G B; Jardine, L J & Mansourov, O A
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Coupled THM analysis of the single-heater test at yucca mountain

Description: This paper presents a summary of results from the Single-Heater Test (SHT) at Yucca Mountain, Nevada. In the SHT, a horizontal, 5-m-long, line-heat source was used to heat a rock pillar for nine months. Moisture movement was monitored during and after heating using electrical-resistance tomography (ERT) and neutron-logging techniques. Results indicate drying in regions of the rock where temperature reached 60°C and above. The drying zone is asymmetric and is not centered on the heater, but has … more
Date: January 25, 1999
Creator: Blair, S. C.; Buscheck, T. A.; Daily, W. D.; Lin, W. & Ramirez, A. L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

In situ examination of moving crack tips in ordered intermetallics.

Description: Recent studies have shown that high stress concentrations at moving crack tips in the intermetallic compound NiTi can induce a crystalline-to-amorphous (C-A) transformation of the crack tip region. This stress-induced C-A transformation has a temperature dependence and crystallization behavior similar to those of ion irradiation-induced C-A transformation of NiTi. The present study examines if these similarities between stress- and irradiation-induced amorphization hold true for two other inter… more
Date: January 25, 1999
Creator: Heuer, J.; Lam, N. Q.; Okamoto, P. R. & Stubbins, J. F.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Legacy material work-off project

Description: Los Alamos National Laboratory (LANL) and its subcontractors recently completed a nine-month legacy material clean-up effort. Legacy materials were defined as chemicals, hazardous, non-hazardous, and both hazardous and radioactive (mixed), that no longer served a programmatic use and had no identified individual owner within the Laboratory. Once personnel identified the legacy materials, the items were transferred to Solid Waste Operation`s (EM-SWO) control. Upon completing this process, the re… more
Date: January 25, 1999
Creator: Sloan, Timothy J. & Baker, Don H., IV
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
Back to Top of Screen