Research Achievements Review, volume II
Materials research - diffusion bonding methods, stress corrosion tests, nondestructive testing, material designs for electronic equipment, and nonmetallic material development.
SPACECRAFT COMPONENT↗
SEARCH · Engineering Papers
Results for “Diffusion Bonding”
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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Laminated sheet composites reinforced with modular filament sheet
Aluminum and magnesium composite sheet laminates reinforced with low density, high strength modular filament sheets are produced by diffusion bonding and explosive bonding. Both processes are accomplished in normal atmosphere and require no special tooling or cleaning other than wire brushing the metal surfaces just prior to laminating.
Reece, O. Y.↗
Evaluation of methods for nondestructive testing of brazed joints
Evaluation of nondestructive methods of testing brazed joints reveals that ultrasonic testing is effective in the detection of nonbonds in diffusion bonded samples. Radiography provides excellent resolutions of void or inclusion defects, and the neutron radiographic technique shows particular advantage for brazing materials containing cadmium.
Kanno, A.↗
Zero Leakage Design for Ducts and Tube Connections for Deep Space Travel. Volume 4 - New Connector Designs and Testing Final Report, 5 Jul. 1963 - 30 Jun. 1967
Omega seal, diffusion bonded, pressure welded, and high temperature separable connector designs and environmental tests
Laniewski, J. P.↗
Oxidation resistant porous material for transpiration cooled vanes
Porous metal sheet with controlled permeability was made by space winding and diffusion bonding fine wire. Two iron-chromium-aluminum alloys and three-chromium alloys were used: GE 1541 (Fe-Cr-Al-Y), H 875 (Fe-Cr-Al-Si), TD Ni Cr, DH 245 (Ni-Cr-Al-Si) and DH 242 (Ni-Cr-Si-Cb). GE 1541 and H 875 were shown in initial tests to have greater oxidation resistance than the other candidate alloys and were therefore tested more extensively. These two materials were cyclic furnace oxidation tested in air at 1800 and 2000 F for accumulated exposure times of 4, 16, 64, 100, 200, 300, 400, 500, and and 600 hours. Oxidation weight gain, permeability change and mechanical properties were determined after exposure. Metallographic examination was performed to determine effects of exposure on the porous metal and electron beam weld joints of porous sheet to IN 100 strut material. Hundred hour stress rupture life and tensile tests were performed at 1800 F. Both alloys had excellent oxidation resistance and retention of mechanical properties and appear suitable for use as transpiration cooling materials in high temperature gas turbine engines.
Madsen, P.↗
Nondestructive test of regenerative chambers
Flat panels simulating internally cooled regenerative thrust chamber walls were fabricated by electroforming, brazing and diffusion bonding to evaluate the feasibility of nondestructive evaluation techniques to detect bonds of various strength integrities. Ultrasonics, holography, and acoustic emission were investigated and found to yield useful and informative data regarding the presence of bond defects in these structures.
Malone, G. A.↗
Fracture of boron filaments in an aluminum matrix.
The B-Al composite specimens tested in this study were fabricated by diffusion bonding of 1230 aluminum foil and boron filaments placed in alternate layers, using an acrylic resin solution to maintain filament spacing. The specimens were put under tensile stresses parallel to the filaments, and filament fracture was monitored acoustically under loads. Fracture of specimens under loads was caused by break propagation with a characteristic wedge-type fragmentation pattern indicating its direction. The aluminum foil matrix of the specimens failed by ductile shear type fracture after the break of the filaments.
Steele, J. H.↗
Evaluation of forming and manufacturing characterisitics of boron/aluminum materials
Low cost techniques were evaluated for forming boron-reinforced aluminum structural shapes from diffusion-bonded flat sheet and plate. Successful forming was accomplished on fully consolidated material up to .46 cm (0.180) in thick. Five hot section 12 in long were formed from 0.100 thick flat plates 12 in long by 7 in wide. Three of the hat sections were tested in cyclic compression to demonstrate the performance capability of structures by this type of low-cost secondary fabrication. The structural efficiency of these hats was found to be equal or superior to similar structures fabricated by more costly techniques.
Dolowy, J. F., Jr.↗
Evaluation of dispersion strengthened nickel-base alloy heat shields for space shuttle application
The work reported constitutes the first phase of a two-phase program. Vehicle environments having critical effects on the thermal protection system are defined; TD Ni-20Cr material characteristics are reviewed and compared with TD Ni-20Cr produced in previous development efforts; cyclic load, temperature, and pressure effects on TD Ni-20Cr sheet material are investigated; the effects of braze reinforcement in improving the efficiency of spotwelded, diffusion-bonded, or seam-welded joints are evaluated through tests of simple lap-shear joint samples; parametric studies of metallic radiative thermal protection systems are reported; and the design, instrumentation, and testing of full-scale subsize heat shield panels are described. Tests of full-scale subsize panels included simulated meteoroid impact tests; simulated entry flight aerodynamic heating in an arc-heated plasma stream; programmed differential pressure loads and temperatures simulating mission conditions; and acoustic tests simulating sound levels experienced by heat shields during about boost flight. Test results are described, and the performances of two heat shield designs are compared and evaluated.
Johnson, R., Jr.↗
Thin-film diffusion brazing of titanium alloys
A thin film diffusion brazing technique for joining titanium alloys by use of a Cu intermediate is described. The method has been characterized in terms of static and dynamic mechanical properties on Ti-6Al-4V alloy. These include tensile, fracture toughness, stress corrosion, shear, corrosion fatigue, mechanical fatigue and acoustic fatigue. Most of the properties of titanium joints formed by thin film diffusion brazing are equal or exceed base metal properties. The advantages of thin film diffusion brazing over solid state diffusion bonding and brazing with conventional braze alloys are discussed. The producibility advantages of this process over others provide the potential for producing high efficiency joints in structural components of titanium alloys for the minimum cost.
Mikus, E. B.↗
A cascade investigation of a convection- and film-cooled turbine vane made from radially stacked laminates
Heat-transfer was investigated on an air-cooled turbine vane made from photoetched laminates that were joined by diffusion bonding. Data from the investigation were compared with data of an impingement-, convection-, and film-cooled vane and a full-coverage film-cooled vane, and data of a transpiration-cooled vane.
Gladden, H. J.↗
The tensile failure modes of metal-matrix composite materials
The strengths of individual boron fibers extracted from various as-received and thermally fatigued aluminum alloy matrix materials were measured. The results are described in terms of a Weibull distribution, and strengths of composites fabricated from these fibers are calculated in terms of lower and upper bounds. Tests conducted on composite specimens indicated that strengths approaching the upper bounds can be achieved in composites fabricated by normal diffusion bonding techniques. Cyclic temperature changes effectively reduced the strength values toward the lower bounds. It was concluded that this effect resulted from the degradation of the strength of the fiber-matrix bond.
Wright, M. A.↗
Fabrication of tungsten wire reinforced nickel-base alloy composites
Fabrication methods for tungsten fiber reinforced nickel-base superalloy composites were investigated. Three matrix alloys in pre-alloyed powder or rolled sheet form were evaluated in terms of fabricability into composite monotape and multi-ply forms. The utility of monotapes for fabricating more complex shapes was demonstrated. Preliminary 1093C (2000F) stress rupture tests indicated that efficient utilization of fiber strength was achieved in composites fabricated by diffusion bonding processes. The fabrication of thermal fatigue specimens is also described.
Brentnall, W. D.↗
Development of impact resistant boron/aluminum composites for turbojet engine fan blades
Composite fabrication was performed by vacuum press diffusion bonding by both the foil-filament array and preconsolidated monotape methods. The effect of matrix material, fiber diameter, matrix enhancement, fiber volume reinforcement, test temperature, angle-plying, notch, impact orientation, processing variables and fabrication methods on tensile strength and Charpy impact resistance are evaluated. Root attachment concepts, were evaluated by room and elevated temperature tensile testing, as well as by pendulum-Izod and ballistic impact testing. Composite resistance to foreign object damage was also evaluated by ballistic impacting of panels using projectiles of gelatin, RTV rubber and steel at various velocities, and impingement angles. A significant improvement in the pendulum impact resistance of B-Al composites was achieved.
Melnyk, P.↗
Joining and fabrication of metal-matrix composite materials
Manufacturing technology associated with developing fabrication processes to incorporate metal-matrix composites into flight hardware is studied. The joining of composite to itself and to titanium by innovative brazing, diffusion bonding, and adhesive bonding is examined. The effects of the fabrication processes on the material properties and their influence on the design of YF-12 wing panels are discussed.
Royster, D. M.↗
Combined joining process for dissimilar metals: A concept
Combined brazing and diffusion bonding process for aluminum and stainless steel saves time and simplifies processing. Test show that resulting bond can withstand internal pressures up to 1,000 psi.
Beuyukian, C. S.↗
Silicon crystal as a low work function collector
A test vehicle with a low work function collector which can be incorporated in a thermionic converter was constructed from standard vacuum components including an ultrahigh vacuum ion pump. The collector assembly was fabricated by diffusion bonding a (100) oriented silicon single crystal to a molybdenum block. The silicon surface was treated with cesium and oxygen to produce an NEA-type condition and the results were tested by photoemission and work function measurements. An n-type silicon collector was successfully activated to a work function of 1.0 eV, which was verified by photoemission spectral yield measurements. The stability test of an activated surface at elevated temperatures was conducted in the range from room temperature to 619 K, which was slightly lower than the designed collector temperature of 700 K. The work function measurements clearly demonstrated that the behavior of cesium replenishment on the activated Si surface was similar in nature to that of a metallic surface; that is, the loss of cesium by thermal desorption could be compensated by maintaining an adequate vapor pressure of cesium.
Chang, K. H.↗
Fracture mechanics correlation of boron/aluminum coupons containing stress risers
The mechanical behavior of boron/aluminum near stress risers has been studied and reported. This effort was directed toward defining the tensile behavior of both unidirectional and (0/ plus or minus 45) boron/aluminum using linear elastic fracture mechanics (LEFM). The material used was 5.6-mil boron in 6061 aluminum, consolidated using conventional diffusion bonding techniques. Mechanical properties are reported for both unidirectional and (0/ plus or minus 45) boron/aluminum, which serve as control data for the fracture mechanics predictions. Three different flawed specimen types were studied. In each case the series of specimens remained geometrically similar to eliminate variations in finite size correction factors. The fracture data from these tests were reduced using two techniques. They both used conventional LEFM methods, but the existence of a characteristic flaw was assumed in one case and not the other. Both the data and the physical behavior of the specimens support the characteristic flaw hypothesis. Cracks were observed growing slowly in the (0/ plus or minus 45) laminates, until a critical crack length was reached at which time catastrophic failure occurred.
Adsit, N. R.↗