Publications

We have measured 1/f noise in MOS transistors as a function of gate and drain bias, total ionizing dose, and postirradiation biased annealing time. The transistors tested varied in size, radiation hardness, and process technology. The radiation-induced 1/f noise correlates strikingly with the oxide trap charge through irradiation and anneal, but not with interface-trap charge, for frequencies up to 10 kHz. This implies that oxide trapped charge is the pre-dominant factor which leads to the increased 1/f noise in irradiated MOS devices. © 1990 IEEE

The electric field dependence of radiation-induced interface-trap formation has been reported to be different for metal-gate capacitors and polysilicon-gate capacitors and transistors. For metal-gate capacitors, interface-trap formation steadily increases with increasing positive field. On the other hand, for polysilicon-gate capacitors and transistors, interface-trap buildup peaks near fields of 1 MV/cm to 2 MV/cm and decreases with an approximate E{sup {minus}1/2} dependence at higher fields. The previously reported field dependence for interface-trap generation for Al-gate capacitors is consistent at all fields with McLean's physical explanation of the two-stage process, which depends on hydrogen ion (H {sup +}) release in the bulk of the oxide as radiation-induced holes transport to either interface via polaron hopping. Above 1 MV/cm, the field dependence of interface-trap buildup for polysilicon-gate devices is inconsistent with this model. Instead, it is similar to the field dependence for hole-trapping in SiO{sub 2}, suggesting that hole trapping may play a key role in interface-trap generation in Si-gate devices. However, recent studies of the time-dependence of interface-trap buildup have known that hole trapping cannot be the rate-limiting step in interface-trap buildup in polysilicon gate devices. Consistent with McLean's physical explanation of the two-stage process, the rate-limiting step in interface-trap formation appears to be H{sup +} transport to the Si/SiO{sub 2} interface. We will show that the electric field dependence of radiation-induced oxide- and interface-trap charge buildup for both polysilicon and metal-gate transistors follows an approximate E{sup {minus}1/2} field dependence over a wide range of electric fields when electron-hole recombination effects are included. Based on these results a hole trapping/hydrogen transport (HT){sup 2} model for interface-trap buildup is proposed.

Short communication.

The identification of unknown phases in the JCPDS-ICDD Powder Diffraction File (PDF) using diffraction data is a three-step process. First, the Search step rapidly screens the entire PDF to produce a list of candidate solutions that correspond to the unknown phase's d-spacings and chemistry. Second, the Match step examines closely every aspect of each phase in the candidate list, vs the unknown, to make the final identification. Third, the Decision step: Does the solution found make crystal-chemical-thermodynamic sense A hindrance to the identification process for electron diffraction applications is that the PDF consists of x-ray diffraction powder data. The present Elemental and Interplanar Spacing Index (EISI) book is based on the successful 1979 Max-d/Alphabetical Index rules, but with significantly enhanced capability, as it utilizes the combined NIST/Sandia/ICDD Database. The EISI is designed to be used independently as a searching tool. As a searching tool it provides a list of candidate phases for consideration as solutions to the unknown phase diffraction data. The EISI index was designed to assist the actual steps taken by an Analytical Electron Microscope (AEM) diffractionist when confronted with an unknown diffraction dataset: the assemblage and d-spacing searching of a microfile of data containing chemically correct phases. The construction of the NIST/Sandia/ICDD Database overcomes many of the disadvantages associated with searching x-ray derived databases for solutions to electron diffraction problems. 8 refs., 1 fig.

The activities involved in establishing a Computer Integrated Manufacturing (CIM) database at Sandia National Laboratories (SNL) are part of a common effort to implement a proactive data administration function across administrative and technical databases. Data administration activities include the establishment of corporate data dictionary, a corporate information model, and a library of important objects and their relationships with other objects. Processes requiring information will be identified and supported with future information systems that share administrative and technical data. The process to create databases is being established based upon accepted engineering design practices. This paper discusses the CIM database, presents the selected information modeling technique and describes the information engineering process. 9 refs.

A simplified, rugged VISAR (Velocity Interferometer System for Any Reflector) system has been developed using a non-removable delay element and an essentially non-adjustable interferometer cavity. In this system, the critical interference adjustments are performed during fabrication of the cavity, freeing the user from this task. Prototype systems are easy to use and give extremely high quality results. 6 refs., 7 figs.

The High-Temperature Borehole Televiewer is a downhole instrument which provides acoustic pictures of the borehole walls that are suitable for casing inspection and fracture detection in geothermal wells. The Geothermal Drilling Organization has funded the development of a commercial tool survivable to temperatures up to 275{degree}C and pressures of 5000 psi. A real-time display on an IBM-compatible PC was included as part of the developmental effort. This paper describes the three principal components are: the mechanical section, the electronics, and the computer software and hardware. Each of these three components are described with special attention to important design changes most pertinent to a high temperature environment. The results of two field tests of the televiewer system are also described. 7 refs., 4 figs.

Early attempts at estimation of stress wave damage in blasting by use of finite element analysis met with limited success due to numerical instabilities that prevented calculations from being carried to late times after significant fragmentation had occurred. A new damage model based on microcrack growth in tension allows finite element calculations which remain stable at late times. Estimation of crater profiles for blasting experiments in granite, using laboratory properties for all parameters, demonstrate a high level of success for this damage model. However, estimated crater profiles show systematic differences from excavated crater profiles which motivate further developments of this model. 19 refs., 16 figs.

Borated stainless steel tensile testing is being conducted at Sandia National Laboratories (SNL). The goal of the test program is to provide data to support a code case inquiry to the ASME Boiler and Pressure Vessel Code, Section 3. The adoption by ASME facilitates a materials qualification for structural use in transport cask applications. The borated stainless steel being tested conforms to ASTM specification A-887, which specifies 16 grades of material as a function of boron content (0.20% to 2.25%) and fabrication technique. For transport cask basket applications, the potential advantage to using borated stainless steel arises from the fact that the structural and criticality control functions can be combined into one material. The test program at SNL involves procuring material, machining test specimens, and conducting the tensile tests. From test measurements obtained so far, general trends indicate that tensile properties (yield strength and ultimate strength) increase with boron content and are in all cases superior to the minimum required properties established in SA-240, Type 304, a typical grade of austenitic stainless steel. Therefore, in a designed basket, web thickness using borated stainless steel would be comparable to or thinner than an equivalent basket manufactured from a typical stainless steel without boron additions. 3 figs., 5 tabs.

A 2D-Laser Radar Imaging System consisting of a prototype 2D-Laser Radar Sensor and an Image Processing System is currently being developed as an intrusion detection system capable of immediate detection and quick assessment for perimeter security and surveillance. The objective of this system is to produce a thin laser wall as an invisible intrusion barrier. Since only a small space is needed to create a narrow laser radar wall, this system will work well where there is only limited or narrow zones available to create the secure perimeter. Images are created of objects which penetrate the laser radar wall for assessment and to determine the appropriate alarm response. Such a system can be used to protect against airborne threats from rooftop areas or to guard against ground threats across perimeter zones of critical facilities. This paper will discuss the operational concepts, the technology, and an initial performance of this prototype system. 2 refs., 6 figs.

The use of a negative coefficient of thermal expansion (CTE) mineral filler ({beta}-eucryptite) is examined as a means of reducing CTE of a bismaleimide polymer (Kerimid 601). Results show that {beta}-eucryptite is effective in lowering CTE of the polymer and of glass fabric composites with a filled matrix phase. A theoretical model is presented that effectively predicts CTE of the filled BMI but underestimates the observed results by approximately 15%. The lower predicted CTE is believed to be due to poor interfacial adhesion at the {beta}-eucryptite/bismaleimide interface. Poor interfacial adhesion is supported by ultimate tensile strength results. 27 refs., 7 figs., 3 tabs.

This paper will focus on the electronic and photochemical properties of polysilylenes, with particular emphasis on the many resemblances in the electronic properties of polysilylenes to those of the familiar {pi}-conjugated polymers. In this context, the term {sigma}-conjugation'' will appear in this paper, as it is almost universally prevalent in the field. However, the use of this term should only be interpreted to suggest a correspondence in the electronic properties with those of {pi}-conjugated materials. No direct correspondence in electronic interactions at the atomic level is implied. In fact, the theoretical underpinnings of the mechanism of electron delocalization in {sigma}-bonded systems remain incomplete, at best. The systematic name polysilylene'' will be used in place of the equivalent and widely used term polysilane.'' In this context, these terms are intended to refer to polydiorganosilylenes, i.e. silicon backbones having substituents other than hydrogen. Moreover, since, with the exception of the commercial use of the intractable polydimethylsilylene as a precursor to {beta}-Sic fibers, the overwhelming majority of the interest in the field is in soluble polysilylenes, the discussion here will be of that greatly predominant group of the materials which are fully tractable and processible. 75 refs., 4 figs., 2 tabs.

Short communication.

We have demonstrated that CI{sub 2} RIBE is a useful dry-etch technology for InSb and InAsSb/InSb Strained-Layer Superlattices (SLSs) in spite of the low vapor pressure of the In chlorides. Etching of these materials using both Cl{sub 2} Reactive-Ion-Beam Etching (RIBE) and Ar IBE resulted in extremely smooth surfaces and well controlled etch rates with CI{sub 2} RIBE accelerating the etch rate by approximately a factor of two compared to Ar IBE over the range of beam energies studied. Sloped sidewalls resulted at all tested Cl{sub 2} RIBE energies and are probably caused by sidewall passivation with In chlorides. The anisotropy and reduced etch-induced damage of Cl{sub 2} RIBE is expected to become of critical importance in the fabrication of dense arrays of long-wavelength photodetectors. 2 figs.

A sol-gel method was use to prepare bulk, closed pore, amorphous alumina-silica. Films prepared from this 47wt% Al{sub 2}O{sub 3}- SiO{sub 2} composition were examined by SAW, elipsometry and electrical measurements. The films were found to have a surface area of 1.1 cm{sup 2}/cm{sup 2}, a refractive index of 1.44 at 633 nm, and a relative permittivity of 6.2 at 200 KHz. These properties indicate potential applications as hermetic seals, barrier coatings, dielectric layers for capacitors and passivation coatings for electronic circuits.

Short communication.

We report on the rapid thermal processing (RTP) of Y-123 fibers with and without presintering to form the orthorhombic phase. We show that fibers which were originally semiconducting and tetragonal before rapid thermal processing form normal twinned orthorhombic material after processing for 2--4 seconds at > 1000{degrees}C with a 3 min. cool down in oxygen. They subsequently show {Tc} to 90K and magnetization indicative of substantial diamagnetic shielding. We present the effects of varying the RTP parameters on the morphology, phase, and superconducting properties of a number of tetragonal and orthorhombic Y-123 fibers. 2 refs., 5 figs., 1 tab.

There has long been a need for fast read nonvolatile, rad hard memories for military and space applications. Recent advances in EEPROM technology now allow this need to be met for many applications. Harris/Sandia have developed a 16k and a 256k rad hard EEPROM. The EEPROMs utilize a Silicon-Oxide-Nitride-Oxide-Silicon (SONOS) memory transistor integrated into a 2 {mu}m, rad hard two level metal CMOS process. Both the 16k and the 256k parts have been designed to interface with the Intel 8085 or 80C51 and National 32000 series microprocessors and feature page and block clear modes. Both parts are functionally identical, and are produced by the same fabrication process. They are also pin for pin compatible with each other, except for the extra address and ground pins on the 256k. This paper describes the characteristics of this EEPROM family. 1 ref.

The concentrations of carbon dioxide, methane, sulfur dioxide, nitrous oxides and chlorofluorocarbons is increasing in the earth's atmosphere. Increased concentrations of these trace gases could lead to global warming, increased acid rain and increased UV radiation on the earth's surface; however, the actual impacts are still uncertain and are also the subject of great debate. Application of clean'' energy sources such as geothermal are obviously desirable for decreasing these effects and improving our overall general environment. This paper briefly summarizes the global environment concerns, providing a backdrop for the following papers which describe the geothermal role in future environmental considerations. 5 refs., 2 figs., 1 tab.

Experimental laminar condensation heat transfer data is reported for fluids with Stefan number up to 3.5. The fluid is a member of a family of fluorinated fluids developed in the last decade which have been extensively used in the electronics industry for soldering, cooling, and testing applications. Experiments were performed by suddenly immersing cold copper spheres in the saturated vapor of this fluid, and heat transfer rates were calculated using the quasi-steady temperature response of the spheres. In these experiments, the difference between saturation and wall temperature varied from 0.5{degree}C to 190{degree}C. Over this range of temperature difference, the condensate properties vary significantly. For example, viscosity of the condense varies by a factor of over 50. Corrections for the temperature dependent properties of the condensate therefore were incorporated in calculating the Nusselt number based on the average heat transfer coefficient. The results are discussed in light of past experimental data theory for Stefan number less than 1. To the knowledge of the authors, this is the first reported study of condensation heat transfer for Stefan number greater that unity. 24 refs., 7 figs., 2 tabs.

A method is presented for determining the force spectral density function for a vibration test where a combination of force and acceleration is used for control. First the acceleration spectral density is established based on an envelope of the interface motion between the test item and the mounting structure (the base) in the use (field) environment. The driving point accelerance (acceleration/force) of the test item is measured at the mounting interface. The force required to drive the test item in an acceleration controlled test is then estimated. A force spectral density is then established using the estimated motion controlled force, and a derived force reduction factor. An extremal control vibration test is then performed based on which parameter (input force or input acceleration) reaches based on which parameter (input force or input acceleration) reaches its envelope first. 7 refs., 7 figs., 2 tabs.

The success of probabilistic risk assessment (PRA) has led to numerous improvements to the safety of commercial nuclear power plants. Those very successes, however, have led to situation where the events that PRAs have traditionally modeled are extremely rare. As a result, current PRAs have the potential to be misleading because events previously considered to be unimportant and, thus, not included in the scope of the analyses may now be dominant. This paper provides an assessment of the current status of accident sequence analysis methods and identifies particular limitations that should be addressed in future studies.

Laboratory deformation and permeability measurements have been made on chalk samples from Ekofisk area fields as a function of confining stress and pore pressure to determine the effective stress laws for chalk. An understanding of the effective stress law is essential to obtain correct reservoir-property data from core analysis and is critical for reservoir management studies and reservoir compaction models. A powerful statistical technique known as the response surface method has been used to analyze our laboratory data determine the form of the effective stress law for deformation and permeability. Experiments were conducted on chalk samples that had a range of porosities from 15% to 36%, because porosity is the dominant intrinsic property that effects deformation and permeability behavior of chalk. Deformation of a 36% porosity chalk was highly nonlinear, but the effective stress law was linear, with {alpha} equal to about unity. Lower-porosity samples showed linear strain behavior and a linear effective stress law with {alpha} as low as 0.74. Analysis of the effective stress law for permeability is presented only for the lowest porosity chalk sample because changes in permeability in the higher-porosity chalk samples due to increasing confining stress or pore pressure were not were large enough, to deduce meaningful effective stress relationships. 15 refs., 8 figs., 2 tabs.

In actual circuit application, MOS transistor bias is generally not constant through radiation exposure. Nevertheless, the overwhelming majority of radiation effects studies and hardness assurance testing is performed at constant bias for simplicity and practicality. In the past 15 years, however, it has been shown that oxide- and interface-trap charge buildup and annealing during switched-bias exposures can differ quantitatively and qualitatively from that observed during steady-state exposures. This has made it difficult to develop predictive models of MOS circuit response for actual use conditions, and has introduced uncertainty into hardness assurance testing of MOS circuits. In this summary, defect growth and annealing rates are compared for steady-state and switched-biased irradiations of MOS transistors. A simple method is described to predict MOS oxide-trap charge, interface-trap charge, and mobility degradation during switched-bias exposures from steady-state ( on'' and off'') irradiations. Over a wide range of switching conditions for the devices examined, this method has provided predictions typically accurate to within better than 20%. The maximum error observed to data is less than 40%. This method should allow the total-dose radiation response of MOS circuits in real-use scenarios to be modeled with improved accuracy and flexibility. 9 refs., 3 figs.

Drillhole H-16 is an exploratory test hole, 850.9 ft deep, drilled in eastern Eddy County, New Mexico, to study the hydrologic parameters of possible aquifers and how these aquifers could affect the construction and maintenance of a shaft to be located about 54 ft from the drillhole. This shaft will connect the underground working of the WIPP (Waste Isolation Pilot Plant) site to the surface. Oeophysical logs were taken to measure acoustic velocities, density, radioactivity, porosity, and formation resistivities. This report describes the data collected during the drilling of exploration drillhole H-16. 2 refs., 2 figs., 3 tabs.

Recent legislation mandated the improvement of national competitiveness as a mission of the defense programs of the US Department of Energy. As a consequence, technology transfer --- the process of transferring commercially valuable technologies developed under government sponsorship to industry for commercialization --- is becoming an important emphasis at many DOE laboratories. Technology transfer processes take many forms, and there are different perspectives on how to approach this activity. In this paper, a taxonomy of technology transfer processes at a national laboratory is presented. In addition, the focus and rationale of Sandia National Laboratories' unique new initiative called the Technology Maturation Program is discussed. This program is designed to complete one essential element of technology transfer that advanced technologies toward commercial applications to the point that industry is willing to assume the investment risk. Strategies and program plans designed to improve the effectiveness of Sandia's contribution to enhancing US industry's competitive position in world markets are also presented.

ENDF/B-VI cross sections were released to the testing community in January 1990. Work at Sandia National Laboratories, with pre-released versions of the new cross sections indicates that changes in the neutron-induced charged-particle reactions will significantly affect 14-MeV neutron dosimetry. Reactions that are important for fission reactor dosimetry were examined and most did not change significantly. 12 refs., 3 figs., 3 tabs.

We have systematically varied processing parameters to fabricate PZT 53/47 thin films. Polycrystalline PZT thin films were fabricated by spin depositing Pt coated SiO{sub 2}/Si substrates with alkoxide solutions. Our study focused on two process parameters: (1) heating rate and (2) excess Pb additions. We used rapid thermal processing techniques to vary heating rates from 3{degree}C/min to 8400{degree}C/min. Films were characterized with the following excess Pb additions: 0, 3, 5, and 10 mol %. For all process variations, films with greater perovskite content had better ferroelectric properties. Our best films were fabricated using the following process parameters: an excess Pb addition of 5 mol %, a heating rate of 8400{degree}C/min and annealing conditions of 700{degree}C for 1 min. Films fabricated using these process conditions had a remanent polarization of 0.27 C/m{sup 2} and a coercive field of 3.4 MV/m. 12 refs., 4 figs.

Lost circulation is the phenomenon where circulating drilling fluid is lost to fractures or pores in the rock formation rather than returning to the surface through the wellbore annulus. In geothermal drilling, lost circulation can be a serious problem that contributes greatly to the cost of the average geothermal well. A DOE-sponsored program is underway at Sandia National Laboratories to develop new technology for solving lost circulation problems. The Lost Circulation Technology Development Program currently consists of twelve projects in three areas: technology to plug porous and minor-fracture loss zones; technology to plug major-fracture loss zones; and technology to characterize loss zones. This paper describes the program and highlights recent progress. 12 refs., 10 figs.

The SEU vulnerability of the SA3300 16-bit microprocessor has been characterized, and the effects of two different design revisions on error rate have been explored. We found that the threshold for upset depends on the data pattern written into the general purpose registers. With all bits in the general purpose registers set to logic one, a design with 2-µm n- and p-channel transistor lengths had a threshold LET of 35 MeV-cm2/mg at 25°C and 4.5 volt operation. With all zero's stored in the registers the upset threshold increased by more than a factor of two to 83 MeV-cm2/mg. A second design revision, with 1.25-µm and 1.75-µm n- and p-channel transistor lengths, respectively, was more vulnerable to upset, but exhibited a smaller dependence on logic state. Measured threshold LET was 23 and 35 MeV-cm2/mg with all one's and all zero's, respectively. Microprobe measurements using a pulsed Nd:YAG laser suggest that the observed pattern dependence for both design revisions is due to bipolar photocurrent in a vertical n+pn transistor. A slight temperature dependence was observed in both design revisions. This is consistent with the use of oversized restoring transistors to minimize SEU vulnerability rather than polysilicon feedback resistors. More recent data show thresholds above 120 MeV-cm2/mg with 80 kΩ feedback resistors. © 1990 IEEE

The paper reviews the interaction of plasmas with materials and presents a status summary based on experience in large fusion experiments, laboratory investigations and design studies. The phenomena that are discussed limit the power densities and confinement properties attainable in plasmas; their control is an essential element of the design of future fusion devices. © 1990 IOP Publishing Ltd.

The use of porous oxide coatings, formed using sol-gel chemistry routes, as the discriminating elements of acoustic wave (AW) chemical sensors, is investigated. These coatings provide several unique advantages: durability, high adsorption capacity based on large surface areas, and chemical selectivity based on both molecular size and chemical interactions. The porosity of these coatings is determined by performing nitrogen adsorption isotherms using the AW device response to monitor the uptake of nitrogen at 77 K. The chemical sensitivity and selectivity obtained with this class of coatings is demonstrated using several examples: hydrous titanate ion exchange coatings, zeolite/silicate microcomposite coatings, and surface modified silicate films.

In light sources such as tungsten filament bulbs, fluorescent tubes and gas tube type radioluminescent (RL) lamps, visible light is emitted from a thin surface layer of excited material. In contrast, neon bulbs, xenon flash tubes and lasers emit light generated throughout their volumes. The first group can be characterized as surface emitters and the latter as volumetric emitters. Theoretically, an ideal volumetric light source has definite advantages over a surface source. In reality, practical volumetric sources will have limitations as well. These advantages and limitations will be discussed with particular emphasis on comparisons between current gas tube type RL lamps and the more advanced volumetric RL lamps.

A new generation of digital multimeters was used to compare the ratios of the resistances of wire-wound reference resistors and quantized Hall resistances. The accuracies are better than 0.1 ppM for ratios as large as 4:1 if the multimeters are calibrated with a Josephson array. 9 refs.

A class of borazene polymers was developed which consists of a two‐dimensional array of six‐membered borazene rings with the borons of adjacent borazene rings separated by ‐NH‐ groups. Pyrolysis of these polymers above ∼1000°C leads to crystalline graphite‐like boron nitride (h‐BN). The thermal chemistry of thin films of one polymer deposited on KOH‐eched aluminum was examined by thermal decomposition mass spectroscopy (TDMS) and thermal gravimetric analysis (TGA), and the gas evolution chemistry was found to be essentially complete at temperatures less than 400°C. All products desorb with the same temperature profile and the major desorbing species are NH3 and N2, consistent with a loss of excess nitrogen and hydrogen in the polymer, and HCl from decomposition of byproducts of the synthesis step. Since the formation of ordered crystalline h‐BN films requires heating to temperatures of the order of 1000°C, whereas the gas evolution chemistry is complete by roughly 400°C, it is concluded that gas evolution chemical processes are not rate limiting in BN ceramic production. Copyright © 1990, Wiley Blackwell. All rights reserved

Constitutive modeling and bifurcation analyses are combined with axisymmetric (triaxial), triaxial/torsion, and plane-strain experiments to interpret and anticipate the development of shear localization in rocks. This paper discusses preliminary results. 22 refs., 3 figs.

The effects of total-dose irradiation on PbO-ZrO{sub 2}-TiO{sub 2} ferroelectric capacitors have been studied in detail. It is shown that significant total-dose degradation of ferroelectrics can occur at dose levels greater than 1 Mrad(Si). 6 refs., 5 figs.

A program was undertaken to radiation harden AT&T's existing power integrated circuit technology (BCDMOS) to total dose, gamma dot, SEU, and neutrons. Efforts have centered around hardening and optimizing our CMOS, DMOS, and NPN devices. Initial results indicate a substantial improvement in hardness over our existing commercial technology. © 1990 IEEE

The objective of this work is the development of numerical models of rock fragmentation by blasting that can be applied to oil shale recovery. Specifically, these models should be used to improve mining efficiency, evaluate alternative mining strategies and provide a basis for evaluating the blast design for in situ retort construction. 11 refs., 7 figs.

Studies of falling-ball rheometry in concentrated suspensions, embodying a combination of analysis experiment, and numerical simulation, are discussed. Experiments involve tracking small balls falling slowly through otherwise quiescent suspensions of neutrally buoyant particles. A theory has been developed relating the average ball velocity to the macroscopic suspension viscosity, and, for dilute suspensions, agreement is obtained with Einstein's sheared suspension viscosity. Detailed trajectories of the balls, obtained either with new experimental techniques or by numerical simulation, are statistically interpreted in terms of the mean settling velocity and the dispersion about that mean. We show that falling-ball rheometry, using small balls relative to the suspended particles, can be a means of measuring the macroscopic zero-shear viscosity without disturbing the original microstructure significantly; therefore, falling-ball rheometry can be a powerful tool to study the effects of microstructure on the macroscopic properties of suspensions. 25 refs.

Joining ceramics to metals requires solutions to both scientific and practical engineering problems. Scientific issues include understanding the fundamental nature of adhesion at metal-ceramic interfaces, predicting interfacial reactions, and understanding the relation between chemical bonding and mechanical stresses at the interface on the atomic level. Engineering a specific ceramic-metal joint requires finding the optimum among what may be inherently incompatible properties. The following review briefly outlines some of the different methods for joining ceramics. Following that, some fundamental aspects of ceramic joining are presented. The paper concludes with examples of ceramic bonding in several engineering ceramic systems.

The assumptions, approximations, and uncertainty in the 1-MeV equivalent silicon damage methodology are reviewed. A new silicon displacement kerma function, based on ENDF/B-VI cross sections, is presented and its shape is experimentally confirmed. The issue of an associated 1-MeV equivalent reference kerma value is discussed. 19 refs., 4 figs.

Long term reliability of solder joints in thick film Au hybrid microcircuits require either minimization of the solid state growth of intermetallics or verification that if present, they do not compromise component performance. Intermetallic compounds such as AuIn{sub 2} or AuSn{sub 4} arise from the solid state reaction between Au thick films and 50Pb--50In or 63Sn--37Pb solder alloys, respectively; they are undesirable due to their brittle mechanical behavior caused by lack of a sufficient number of independent slip systems for plastic deformation. In addition, they may alter the resistivity of a circuit and thereby alter electronic performance. This paper will present a brief overview of the Au thick film inks/solder alloy systems whose intermetallic growth kinetics have been characterized at SNL, Albuquerque for hybrid microcircuit electronic applications. 6 refs., 3 figs., 2 tabs.

Examination of the durability of zirconia-coated rigid disks in various environments reveals a sensitivity to the presence of water vapor during sliding. Vacuum and dry air yield contact durabilities of 300 to 400 m, while in 50% relative humidity air the contact life increases to about 20 km. The durability of amorphous carbon-coated disks was also found to be more sensitive to the presence of moisture than to oxygen. The dominant factors affecting wear are believed to be oxidation of metallic debris and interaction of the overcoat layer with water vapor. Tests with ferrite read/write sliders on carbon-coated disks suggest that the pin-on-disc test is a valid simulation of the tribological behavior of this system. Carbon film thickness measurements indicate that the carbon film remains intact without appreciable thinning until the point of failure. 25 refs., 12 figs., 1 tab.

A method is presented for smoothing and differentiating noisy data given on a rectangular grid. The method makes use of a one-dimensional smoothing algorithm to construct the solution to an associated two-dimensional problem. Smoothing parameter selection is automated using a technique that does not require prior knowledge of the amount of noise in the data. Numerical examples are provided demonstrating the application of the method. 4 refs., 8 figs., 2 tabs.

Drillhole H-12 was drilled where hydraulic data were needed to better establish flow characteristics existing south-southeast of the WIPP site. The fluid-bearing zones of interest are the Magenta and Culebra dolomite units of the Rustler Formation. Dissolution of halite in the Rustler Formation has occurred in the uppermost member, but has not yet begun in the lower halite-bearing members. Cuttings and cores were taken at selected intervals and geophysical logs were run over the entire depth of the hole. 3 refs., 2 figs., 3 tabs.

Research has shown that long-term hourly insolation data are necessary to properly size stand-alone photovoltaic systems. Even if these data are available, their direct use requires extensive computing capabilities and is not practical on a routine basis. This paper describes a three-step model that generates realistic long-term hourly insolations from average monthly insolations. The model executes rapidly on a personal computer and generates the hourly data needed to properly size stand-alone systems. The approach used to develop this model was unique in that system performance predictions rather than statistical properties were used to verify that the synthetic data were representative of actual data. Results of verification tests show that array sizes resulting from the synthetic data are within 6% of the array sizes resulting from actual hourly data for any system with at least two days of energy storage. 5 figs., 4 tabs.

Sandia designed, built, and tested prototypes of a new photovoltaic concentrator module, the Sandia Baseline Module 3 (SBM3). The SBM3 is intended to be a high-efficiency module that can be readily adapted for commercial production. It consists of a 2 by 12 parquet of lenses arranged with 24 cells in an aluminum housing. The geometric concentration ratio is 185. The cells were made at the University of New South Wales and employ prismatic covers designed by ENTECH. The module features a new concept in cell assemblies in that the cells are soldered directly to a copper heat spreader, eliminating the expensive ceramic wafer and heat sink that have been used in previous designs. Electrical isolation was accomplished by anodizing the electrophoretically coating the aluminum housing. Lessons learned during construction and testing of the SBM3 are presented, along with the outdoor performance characteristics of prototype modules and results from qualification testing. 7 refs., 11 figs.

The Sandia Sorption Data Management System (SSDMS II) stores and retrieves trace element sorption data. The data management system has potential applications in performance assessment studies of transuranic high- and low-level, and toxic waste sites. The current version stores information describing the degree of sorption, the compositions of rocks and solutions used in the sorption experiment, and the experimental procedures. This User's Manual describes SSDMS II data searches, creation of new data files, and the merging of new with existing data base files. These extended data bases can be used to examine relationships among experimental variables, mineralogy of the substrate, water composition, and sorption ratios. Examples of using SSDMS II with a data base of radionuclide sorption data are given. 3 figs., 13 tabs.

Under the sponsorship of the US Department of Energy Office of Defense Programs, Sandia National Laboratories' Transportation Technology Center has developed computerized software to assist state and local governments in determining highway routing alternatives for radioactive materials. The techniques have a still wider application in analyzing route alternatives for all hazardous materials transport activities. The specific techniques discussed in this presentation are the latest update of the StateGEN/StateNET model structure and routing algorithm which contains the codified US Department of Transportation (DOT) Guidelines for Highway Route Controlled Quantity shipments of radioactive materials. 6 refs.