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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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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Method of making porous conductive supports for electrodes

Porous conductive supports for electrochemical cell electrodes are made by electroforming thin corrugated nickel foil, and by stacking pieces of the corrugated foil alternatively with pieces of thin flat nickel foil. Corrugations in successive corrugated pieces are oriented at different angles. Adjacent pieces of foil are bonded by heating in a hydrogen atmosphere and then cutting the stack in planes perpendicular to the foils.

Schaer, G. R.↗
NASA NTRS1974

Solar simulator mirror refurbishment

Solar simulator mirrors were refurbished. Two different refurbishment methods were employed. In the first, the electroformed mirror replica was removed from the casting and replaced with a new mirror replica. In the second, only the aluminized surface, with its protective overcoat, was removed from the mirror and replaced after cleaning of the nickel surface.

Leverton, W. R.↗
NASA NTRS1973

Nondestructive evaluation of regeneratively cooled thrust chambers for rocket engines

Review of a development program for nondestructive tests applicable to hardware with electroformed nickel bonds. The four steps of the program include the selection of some most promising nondestructive evaluation methods out of existing methods, the fabrication of test panels for simulation of cooled thrust chamber walls with bonds of various integrities, the evaluation of the test panels by personnel without previous knowledge of the planned bond integrity, and the verification of actual bond strength in the test panels by destructive tests. Ultrasonics, acoustic emission and holography are evaluated in nondestructive testing applications.

Stauffis, C. R.↗
NASA NTRS1975

Space shuttle orbit maneuvering engine

Data on the performance, stability, and thermal characteristics of an OME operating with an alternate injector configuration and with alternate propellants was obtained. The design, manufacturing, and operating characteristics of an electroformed, regeneratively cooled thrust chamber were also derived. Subscale and full scale tests provide data relating to off-design and transient operation.

Pauckert, R. P.↗
NASA NTRS1975

Materials and processes for space shuttle's engines

It is pointed out that over 50 different alloys are used in construction of the space shuttle main engines (SSME). Primary construction of the SSME is by welding or brazing of wrought and cast components. Welding processes involve both gas tungsten-arc welds and electron-beam welds. Electroforming has been developed as a process to fabricate and bond structural members for the SSME. Important aspects in the selection of materials and processes are related to weight saving considerations and the high-pressure hydrogen environment. Special problems and their solution in the case of various engine components are discussed, giving attention to the oxidizer preburner, the high pressure oxidizer turbopump, and the heat exchanger.

J. R. Lewis↗
NASA NTRS1977

Fabrication of ultra-low-noise amplifier

Three construction techniques reduce noise temperature of microwave parametric amplifier. Techniques include electroformed idler cavity, screw-tuned idler, and low-loss matching section.

Kraemer, E.↗
NASA NTRS1976

Development of explosive welding procedures to fabricate channeled nozzle structures

Research was conducted to demonstrate the feasibility of fabricating a large contoured structure with complex internal channeling by explosive welding procedures. Structures or nozzles of this nature for wind tunnel applications were designed. Such nozzles vary widely in their complexity. However, in their simplest form, they consist of a grooved base section to which a cover sheet is attached to form a series of internal cooling passages. The cover sheet attachment can be accomplished in various ways: fusion welding, brazing, and diffusion welding. The cover sheet has also been electroformed in place. Of these fabrication methods, brazing has proved most successful in producing nozzles with complex contoured surfaces and a multiplicity of internal channels.

Pattee, H. E.↗
NASA NTRS1976

Experimental and theoretical investigation of fatigue life in reusable rocket thrust chambers

During a test program to investigate low-cycle thermal fatigue, 13 rocket combustion chambers were fabricated and cyclically test fired to failure. Six oxygen-free, high-conductivity (OFHC) copper and seven Amzirc chambers were tested. The chamber liners were fabricated of copper or copper alloy and contained milled coolant channels. The chambers were completed by means of an electroformed nickel closeout. The oxidant/fuel ratio for the liquid oxygen and gaseous hydrogen propellants was 6.0. The failures in the OFHC copper chambers were not typical fatigue failures but are described as creep rupture enhanced by ratcheting. The coolant channels bulged toward the chamber centerline, resulting in progressive thinning of the wall during each cycle. The failures in the Amzirc alloy chambers were caused by low-cycle thermal fatigue. The lives were much shorter than were predicted by an analytical structural analysis computer program used in conjunction with fatigue life data from isothermal test specimens, due to the uneven distribution of Zr in the chamber material.

Hannum, N. P.↗
NASA NTRS1976

PMR polyimide/graphite fiber composite fan blades

Ultrahigh speed fan blades, designed in accordance with the requirements of an ultrahigh tip speed blade axial flow compressor, were fabricated from a high strength graphite fiber tow and a PMR polyimide resin. The PMR matrix was prepared by combining three monomeric reactants in methyl alcohol, and the solution was applied directly to the reinforcing fiber for subsequent in situ polymerization. Some of the molded blades were completely finished by secondary bonding of root pressure pads and an electroformed nickel leading edge sheath prior to final machining. The results of the spin testing of nine PMR fan blades are given. Prior to blade fabrication, heat resin tensile properties of the PMR resin were examined at four formulated molecular weight levels. Additionally, three formulated molecular weight levels were investigated in composite form with both a high modulus and a high strength fiber, both as-molded and postcured, in room temperature and 232 C transverse tensile, flexure and short beam shear. Mixed fiber orientation panels simulating potential blade constructions were also evaluated. Flexure tests, short beam shear tests, and tensile tests were conducted on these angle-plied laminates.

Cavano, P. J.↗
NASA NTRS1979

Electrodeposition applications for the Space Shuttle Main Engine

Electrodeposition processes play a key role in the fabrication and in-service performance of the Space Shuttle Main Engine. Applications range from the electroforming of the main combustion chamber to the deposition of high-purity copper or gold for hydrogen embrittlement protection of susceptible materials of construction, or nickel for mechanical protection of foam insulated propellant ducts. Techniques for controlling electrolyte purity, verification of deposit integrity, and deposit profile and thickness are reported. The use of in-situ techniques (cell-plating) for localized plating and repair of damaged substrate materials are summarized.

Otousa, J. E.↗
NASA NTRS1976

Evaluation of advanced microelectronic fluxless solder-bump contacts for hybrid microcircuits

Technology for interconnecting monolithic integrated circuit chips with other components is investigated. The advantages and disadvantages of the current flip-chip approach as compared to other interconnection methods are outlined. A fluxless solder-bump contact technology is evaluated. Multiple solder-bump contacts were formed on silicon integrated circuit chips. The solder-bumps, comprised of a rigid nickel under layer and a compliant solder overlayer, were electroformed onto gold device pads with the aid of thick dry film photomasks. Different solder alloys and the use of conductive epoxy for bonding were explored. Fluxless solder-bump bond quality and reliability were evaluated by measuring the effects of centrifuge, thermal cycling, and high temperature storage on bond visual characteristics, bond electrical continuity, and bond shear tests. The applicability and suitability of this technology for hybrid microelectronic packaging is discussed.

Mandal, R. P.↗
NASA NTRS1981

Far-infrared bandpass filters from cross-shaped grids

The optical transmission characteristics of electroformed metal grids with inductive and capacitive cross patterns have been investigated in the far-infrared spectral region. The transmission characteristics of one- and two-grid devices are represented by transmission line theory parameters. Results are used to suggest construction guidelines for two-grid bandpass filters.

Tomaselli, V. P.↗
NASA NTRS1981

Forming electrical interconnections through semiconductor wafers

An information processing system based on CMOS/SOS technology is being developed by NASA to process digital image data collected by satellites. An array of holes is laser drilled in a semiconductor wafer, and a conductor is formed in the holes to fabricate electrical interconnections through the wafers. Six techniques are used to form conductors in the silicon-on-sapphire (SOS) wafers, including capillary wetting, wedge extrusion, wire intersection, electroless plating, electroforming, double-sided sputtering and through-hole electroplating. The respective strengths and weaknesses of these techniques are discussed and compared, with double-sided sputtering and the through-hole plating method achieving best results. In addition, hollow conductors provided by the technique are available for solder refill, providing a natural way of forming an electrically connected stack of SOS wafers.

Anthony, T. R.↗
NASA NTRS1982

Overview of a new slicing method: Fixed Abrasive Slicing Technique (FAST)

The fixed abrasive slicing technique (FAST) was developed to slice silicon ingots more effectively. It was demonstrated that 25 wafers/cm can be sliced from 10 cm diameter and 19 wafers/cm from 15 cm diameter ingots. This was achieved with a combination of machine development and wire-blade development programs. Correlation was established between cutting effectiveness and high surface speeds. A high speed slicer was designed and fabricated for FAST slicing. Wirepack life of slicing three 10 cm diameter ingots was established. Electroforming techniques were developed to control widths and prolong life of wire-blades. Economic analysis indicates that the projected add-on price of FAST slicing is compatible with the DOE price allocation to meet the 1986 cost goals.

Schmid, F.↗
NASA NTRS1983

Normal-Incidence Soft-X-Ray Mirror

Multilayered interference structure has about 6 percent reflectivity. Normal-incidence X-Ray Mirror, bent into spherical surface of radius 1.1mm used to image electroformed-nickel grid onto photographic film sensitive to soft X-rays. Grid set at distance of 1,067 mm from mirror, illuminated by simple Coolidge-type X-ray tube with carbon anode operated from 1.5KV supply. Film set at distance of 1,186 mm from mirror with resultant magnification of 1.11.

Underwood, J. H.↗
NASA NTRS1982

Cassegrainian concentrator solar array exploratory development module

A miniaturized Cassegrainian concentrator solar array concept is under development to reduce the cost of multi-kW spacecraft solar arrays. A primary parabolic reflector directs incoming solar energy to a secondary, centrally mounted inverted hyperbolic reflector and down onto a solar cell mounted on an Mo heat spreader on a 0.25 mm thick Al heat fin. Each unit is 12.7 mm thick, which makes the concentrator assembly roughly as thick as a conventional panel. The output is 100 W/sq and 20 W/kg, considering 20% efficient Si cells at 100 suns. A tertiary light catcher is mounted around the cell to ameliorate optic errors. The primary reflector is electroformed Ni with protective and reflective coatings. The cells have back surface reflectors and a SiO antireflective coating. An optical efficiency of 80% is projected, and GaAs cells are being considered in an attempt to raise cell efficiencies to over 30%.

Patterson, R. E.↗
NASA NTRS1985

Polyurethane-Foam Maskant

Brown wax previously used to mask hardware replaced with polyurethane foam in electroplating and electroforming operations. Foam easier to apply and remove than wax and does not contaminate electrolytes.

Bodemeijer, R.↗
NASA NTRS1984

Topics in the optimization of millimeter-wave mixers

This report is in three parts: 1. In the first part a user-oriented computer program for the analysis of single-ended Schottky diode mixers is described. The program is used to compute the performance of a 140-220 GHz mixer and excellent agreement with measurements at 150 and 180 GHz is obtained. A sensitivity analysis indicates the importance of various diode and mount characteristics on the mixer performance. 2. The second part of this report describes a computer program for the analysis of varactor diode multipliers. The diode may operate in either the reverse biased varactor mode or with substantial forward current flow where the conversion mechanism is predominantly resistive. In addition, a design for a varactor diode doubler, tunable over an output frequency range of 150-220 GHz, is given. The doubler has 10-20% conversion efficiency with an instantaneous bandwidth of 3%. 3. The third section of this report contains a description and analysis of i new H-plane rectangular waveguide transformer. The transformer can be made luckily and easily in split-block waveguide using a standard slitting saw. It is particularly suited for use in the millimeter-wave band, replacing conventional electroformed stepped transformers. A theoretical analysis of the transformer is given, and good agreement is obtained with measurements made at X-band. Design curves are included for transitions which have a VSWR <1.2 over a full waveguide band when the impedance ratio is as high as 4 to 1.

Millimeter-wave↗