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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Cryogenic treatment of laminated copper-clad microwave circuit boards eliminates stresses that cause warpage when a circuit is etched on one side of the board. After etching, the stresses may be eliminated to reduce warpage.
Analysis of cylindrical reactor fuel pin for clad stress caused by fission gases
Stress relief of copper-clad microwave circuit laminates to reduce and prevent warpage
Radial power tailoring for uranium dioxide-T-111 clad reactor with contained fission product gases
Development of ductile oxidation-resistant cladding alloys for thoria dispersion, strengthened nickel and nickel-chromium
Three oxidation-resistant alloy foil claddings for protecting typical gas turbine engine alloys of nickel and cobalt
Mach 1 burner rig tests at 2100 F for oxidation resistance evaluation of NiCrAl and FeCrAlY claddings on TD-NiCr
Metallographic and ductility effects of lithium on tungsten-lined titanium alloy clad uranium mononitride cylinders after long term exposure
Tensile and fatigue properties and liquid oxygen compatibility of bilaminate stainless steel-clad titanium prepared by vacuum deposition and explosive welding
Computer program HETRAN to solve two dimensional steady state heat conduction on cladded tube with connecting fin
Oxidation protection of superalloys by thin claddings of Ni-Cr-Al-Si and Fe-Cr-Al-Y alloys examined and compared with commercial aluminide coatings
Oxidation and nitrogen absorption protection of Cr alloy by Ni alloy claddings applied by gas pressure bonding
A Russian paper by A. A. Babad-Zakhryapina contributes much to the understanding of fuel, clad interactions, and thus to nuclear thermionic technology. In that publication the basic diffusion expression is a simple one. A more general but complicated equation for this mass transport results from the present work. With appropriate assumptions, however, the new relation reduces to Babad-Zakhryapina's version.
Computer modeling studies conducted on four-layer silicon-clad dielectric waveguides indicate that the attenuation (alpha) and mode index (beta/K) behave as exponentially damped sinusoids as the silicon thickness is increased. The observed effect can be explained quite simply as a periodic coupling between the guided modes of the lossless structure and the lossy modes supported by the high-refractive index silicon. The attenuation and mode index are significantly altered by conductivity changes in the silicon; an amplitude modulator and an intensity modulator were proposed using these results. Predicted high attenuations in the device may be reduced significantly with a silicon dioxide buffer layer between the semiconductor and the polystyrene guide. Experimental confirmation of the predicted characteristics is still necessary. A number of thin-silicon film waveguides have been RF sputtered but attenuation measurements to verify the damped oscillatory behavior are forthcoming. Conductivity variations of the silicon should demonstrate the modulation capabilities.
A successful brazing process was developed and evaluated for fabricating full-scale titanium-clad Borsic/aluminum skin-stringer panels. A panel design was developed consisting of a hybrid composite skin reinforced with capped honeycomb-core stringers. Six panels were fabricated for inclusion in the program which included laboratory testing of panels at ambient temperatures and 533 K (500 F) and flight service evaluation on the NASA Mach 3 YF-12 airplane. All panels tested met or exceeded stringent design requirements and no deleterious effects on panel properties were detected followng flight service evaluation on the YF-12 airplane.
Etched metallic conductor lines on metal clad polymeric substrates are used for electronic component interconnections. Significant signal losses are observed for microstrip conductor lines used for interconnecting high frequency devices. At these frequencies, the electronic signal travels closer to the metal-polymer interface due to the skin effect. Copper-teflon interfaces were characterized by scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) to determine the interfacial properties. Data relating roughness of the copper film to signal losses was compared to theory. Films used to enhance adhesion are found, to contribute to these losses.
A variety of techniques have been proposed for fabricating integrated optical devices using semiconductors, lithium niobate, and glasses as waveguides and substrates. The use of glass waveguides and their interaction with thin semiconductor cladding layers was studied. Though the interactions of these multilayer waveguide structures have been analyzed here using glass, they may be applicable to other types of materials as well. The primary reason for using glass is that it provides a simple, inexpensive way to construct waveguides and devices.