Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “ADHESIVES”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Rate and time dependent behavior of structural adhesives

Studies on two adhesives (Metlbond 1113 and 1113-2) identified as having applications in the bonding of composite materials are presented. Constitutive equations capable of describing changes in material behavior with strain rate are derived from various theoretical approaches. It is shown that certain unique relationships exist between these approaches. It is also shown that the constitutive equation derived from mechanical models can be used for creep and relaxation loading. A creep to failure phenomenon is shown to exist and is correlated with a delayed yield equation proposed by Crochet. Loading-unloading results are presented and are shown to correlate well with the proposed form of the loading-unloading equations for the modified Bingham model. Experimental results obtained for relaxation tests above and below the glass transition temperature are presented. It is shown that the adhesives obey the time-temperature superposition principle.

Renieri, M. P.↗
NASA NTRS1976

Electrical properties of adhesives used in hybrid microelectronic applications

This paper describes a test program conducted to determine the electrical properties of adhesives used in hybrid microelectronic applications and to develop test methods for measuring these properties. The electrical properties of transistor chips mounted with conductive adhesives are also measured, and the effect of long term storage at high temperature on these devices is determined.

Sergent, J. E.↗
NASA NTRS1977

Adhesion and friction of iron and gold in contact with elemental semiconductors

Adhesion and friction experiments were conducted with single crystals of iron and gold in contact with single crystals of germanium and silicon. Surfaces were examined in the sputter cleaned state and in the presence of oxygen and a lubricant. All experiments were conducted at room temperature with loads of 1 to 50 grams, and sliding friction was at a sliding velocity of 0.7 mm/min. Results indicate that the friction nature of metals in contact with semiconductors is sensitive to orientation, that strong adhesion of metals to both germanium and silicon occurs, and that friction is lower with silicon than with germanium for the same orientation. Surface effects are highly sensitive to environment. Silicon, for example, behaves in an entirely brittle manner in the clean state, but in the presence of a lubricant the surface deforms plastically.

Buckley, D. H.↗
NASA NTRS1977

Development and production of a flame retardant, general purpose, pressure sensitive adhesive tape

The specification results for the finished tape properties were as follows: (1) adhesive strength (180 deg peel) on aluminum from 107 to 143 grams per centimeter (0.6 to 0.8 pounds per inch); (2) adhesive strength (180 deg peel) on stainless steel from 71 to 107 grams per centimeter (0.4 to 0.6 pounds per inch); (3) unwind resistance of 536 to 714 grams per centimeter (3 to 4 pounds per inch); (4) tensile strength minimum of 7143 grams per centimeter (40 pounds per inch); (5) elongation from 5 to 10% at break; (6) tear strength, Elmendorf from 200 to 350 grams (0.44 to 0.77 pounds); and (7) tear strength, tongue from 363 to 408 grams (0.8 to 0.9) pounds).

Monaghan, P. B.↗
NASA NTRS1977

Cryogenic adhesives and sealants: Abstracted publications

Abstracts of primary documents containing original experimental data on the properties of adhesives and sealants at cryogenic temperatures are presented. The most important references mentioned in each document are cited. In addition, a brief annotation is given for documents considered secondary in nature, such as republications or variations of original reports, progress reports leading to final reports included as primary documents, and experimental data on adhesive properties at temperatures between about 130 K and room temperature.

Williamson, F. R.↗
NASA NTRS1977

Structure-property relationships in low-temperature adhesives

Adhesive materials of aliphatic polyester, linear hydroxyl end-capped polybutadienes, or SBS block copolymers are studied with the objective to replace conventional partially aromatic end-reactive polyester-isocyanate adhesives that have shown embrittlement

Schoff, C. K.↗
NASA NTRS1977

A fundamental approach to adhesion: Synthesis, surface analysis, thermodynamics and mechanics

The ability of SEM/EDAX to determine the physical and chemical composition of very small areas was used to study several diverse types of samples representative of NASA-LaRC technology. More systematic investigation was carried out on differences in the results of grit-blasting Ti 6-4 adherends and the presence of extraneous elements, primarily silicon, in some polymer/HT-S fiber composites. Initial results were obtained from a fractured (ILS) short-beam shear specimen, and from Ti 6-4 alloy, before and after a proprietary Boeing anodizing surface preparation for adhesive bonding. Photomicrographs and EDAX spectra were also obtained from new, fractured lap shear strength specimens that employed PPQ and LARC-13 adhesives.

Dwight, D. W.↗
NASA NTRS1977

Polyurethane adhesive with improved high temperature properties

A polyurethane resin with paste activator, capable of providing useful bond strengths over the temperature range of -184 C to 149 C, is described. The adhesive system has a pot life of over one hour. Tensile shear strength ratings are given for various adhesive formulations.

Stuckey, J. M.↗
NASA NTRS1976

Polyimide adhesives for weld-bonding titanium

Two weld bonding processes were developed for joining titanium alloy; one process utilizes a weld-through technique and the other a capillary-flow technique. The adhesive used for the weld-through process is similar to the P4/A5F system and a new adhesive system, CP/CFA, was used in the capillary-flow process. Static property information was generated for weld-bonded joints over the temperature range of 219K (-65 F) to 561K (550 F) and fatigue strength information was generated at room temperature. Significant improvement in fatigue strength was demonstrated for weld-bonded joints over spot-welded joints. A demonstration was made of the applicability of weld-bonding for fabricating stringer stiffened skin panels.

Vaughan, R. W.↗
NASA NTRS1978

Polyimide adhesives for titanium and composite bonding

Approach results in synthesis of addition polyimide adhesives with exceptional high temperature capabilities that show excellent potential for bonding titanium metal, polyimide/graphite composites, and combinations of these materials. Adhesives compatible with materials used in high performance aircraft and spacecraft structures also prove highly desirable in many other applications involving similar adherents.

St. Clair, A. K.↗
NASA NTRS1978

Inspection of adhesive-bonded radiators

Adhesive-bond thickness in honeycomb-sandwich radiators is verified by visual inspection. Markoff on flow tubes created during curing process is directly related to adhesive thickness.

Reed, M. W.↗
NASA NTRS1979

Sealing microcircuits with adhesives

Report describes study of adhesive-sealed packages for hybrid microcircuits. Ten commercially available adhesives were used to seal metal and ceramic packages and were tested for moisture resistance at high humidity.

Licari, J. J.↗
NASA NTRS1978

A fundamental approach to adhesion: Synthesis, surface analysis, thermodynamics and mechanics

Various surface preparations for titanium 6-4 alloy were studied. An anodizing method was investigated, and compared with the results of other chemical treatments, namely, phosphate/fluoride, Pasa-Jell and Turco. The relative durability of the different surface treatments was assessed by monitoring changes in surface chemistry and morphology occasioned by aging at 505 K (450 F). Basic electron spectroscopic data were collected for polyimide and polyphenylquinoxaline adhesives and synthetic precursors. Fractographic studies were completed for several combinations of adherend, adhesive, and testing conditions.

Chen, W.↗
NASA NTRS1979

A fundamental approach to adhesion: Synthesis, surface analysis, thermodynamics and mechanics

Adherend surfaces and fractography were studied using electron spectroscopy for chemical analysis and scanning electron microscopy/energy dispersive analysis of X-rays. In addition, Auger Electron Spectroscopy with depth profiling capability was used. It is shown that contamination of adhesion systems plays an important role not only in determining initial bond strengths but also in the durability of adhesive bonds. It is concluded that the analytical techniques used to characterize and monitor such contamination.

Chen, W.↗
NASA NTRS1979

NR-150 adhesive development

A polyimide precursor adhesive solution, code-named NR-056X, was developed. It reproducibly gives low void, high strength bond lines at both room temperature and 589K (600 F) using either titanium or graphite/polyimide composite adherends having 12.7 mm (1/2 in.) overlaps. Lap shear samples prepared using this adhesive and composite adherends based on graphite/NR-150B2 were shown to have a high degree of resistance to such adverse environments as air at 589K (600 F), high humidity, methyl ethyl ketone and jet fuel. Bond line toughness was illustrated by the complete resistance to cracking in the wedge-crack propagation test. The available evidence indicates that wide area composite to composite or composite to metal bonding should be feasible.

Blatz, P. S.↗
NASA NTRS1979

LARC-13 polyimide adhesive bonding

The development of an addition-curing polyimide adhesive suitable for low pressure bonding without the generation of volatiles during cure is reported. LARC-13 is designed for bonding of polyimide matrix composites and of titanium to be used above 500 F, and is based on an oligomeric bis-nadimide which allows its processing at 50 psi or less, making it suitable for the bonding of fragile honeycomb sandwich structures. Few volatiles are evolved during its cure allowing large enclosed structures to be bonded, and it has high room and elevated temperature strengths and good strength retention after short terms up to 1100 F. LARC-13 was successfully used to bond the outer and inner skins of a polyimide/graphite wing shear panel for 500 F use, and for a short-term exposure up to 1100 F. Preparation of the adhesive, bonding, aging, and testing of lap shear and honeycomb samples are discussed.

Saint Clair, T. L.↗
NASA NTRS1981

New pressure-sensitive silicone adhesive

Adhesive for high or low temperatures does not stretch severely under load. It is produced by combining intermediate-molecular-weight pressure sensitive adhesive which does not cure with silicone resin that cures with catalyst to rubbery tack-free state. Blend of silicone tackifier and cured rubbery silicone requires no solvents in either atmospheric or vacuum environments. Ratio of ingredients varies for different degrees of tack, creep resistance, and tensile strength.

Leiffer, J. L.↗
NASA NTRS1980

Adhesion and friction of iron-base binary alloys in contact with silicon carbide in vacuum

Single pass sliding friction experiments were conducted with various iron base binary alloys (alloying elements were Ti, Cr, Mn, Ni, Rh, and W) in contact with a single crystal silicon carbide /0001/ surface in vacuum. Results indicate that atomic size and concentration of alloying elements play an important role in controlling adhesion and friction properties of iron base binary alloys. The coefficient of friction generally increases with an increase in solute concentration. The coefficient of friction increases linearly as the solute to iron atomic radius ratio increases or decreases from unity. The chemical activity of the alloying elements was also an important parameter in controlling adhesion and friction of alloys, as these latter properties are highly dependent upon the d bond character of the elements.

Miyoshi, K.↗