Growth of boron doped diamond by vapor deposition
Growth of p-type semiconducting diamond by vapor phase deposition using methane-diborane doping gas mixture in presence of diamond seed crystals
Poferl, D. J.↗
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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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Static and Dynamic Analysis, F-14A Boron Horizontal Stabilizer
A static stress analysis and a dynamic modal analysis of the horizontal stabilizer of the F-14A aircraft has been conducted at the Naval Air Development Center employing the NASTRAN program. The structural model contains 1518 elements including bars, rods, shear panels and orthotropic and isotropic membrane elements with 1357 degrees of freedom. Static deflection and stresses, including thermal stresses, under maximum load at room and at elevated temperatures are calculated and results are in good agreement with experimental data. Through application of "Guyan Reduction" the number of degrees of freedom used in the dynamic analysis is reduced to 137 . The frequencies and mode shapes for the first two modes are obtained .
S. L. Huang↗
Graphite and boron-reinforced composite materials data summary
Data summary is collection of information on typical processing techniques. Mechanical properties, and physical properties of advanced composite materials which are being considered for structural applications on advanced space vehicles.
Source record↗
Boron epoxy rocket motor case program
Three 28-inch-diameter solid rocket motor cases were fabricated using 1/8 inch wide boron/epoxy tape. The cases had unequal end closures (4-1/8-inch-diameter forward flanges and 13-inch-diameter aft flanges) and metal attachment skirts. The flanges and skirts were titanium 6Al-4V alloy. The original design for the first case was patterned after the requirements of the Applications Technology Satellite apogee kick motor. The second and third cases were designed and fabricated to approximate the requirements of a small Applications Technology Satellite apogee kick motor. The program demonstrated the feasibility of designing and fabricating large-scale filament-wound solid propellant rocket motor cases with boron/epoxy tape.
Stang, D. A.↗
Fundamental Mechanisms of Tensile Fracture in Aluminum Sheet Unidirectionally Reinforced with Boron Filament
Results are presented from an experimental research effort to gain a more complete understanding of the physics of tensile fracture in unidirectionally reinforced B-Al composite sheet. By varying the degree of filament degradation resulting from fabrication, composite specimens were produced which failed in tension by the cumulative mode, the noncumulative mode, or by any desired combination of the two modes. Radiographic and acoustic emission techniques were combined to identify and physically describe a previously unrecognized fundamental fracture mechanism which was responsible for the noncumulative mode. The tensile strength of the composite was found to be severely limited by the noncumulative mechanism which involved the initiation and sustenance of a chain reaction of filament fractures at a relatively low stress level followed by ductile fracture of the matrix. The minimum average filament stress required for initiation of the fracture mechanism was shown to be approximately 170 ksi, and appeared to be independent of filament diameter, number of filament layers, and the identity of the matrix alloy.
Herring, H. W.↗
Development of boron-epoxy tubular struts for a one-third scale shuttle booster thrust structure.
A one-third scale booster thrust truss structure was designed by Grumman under an in-house program using both boron/epoxy and titanium for the tubular strut members. The boron/epoxy design showed a 22% weight saving and a two phase demonstration program was subsequently funded by NASA-MSFC. In the first phase, structural elements and the most highly loaded center member of the truss were fabricated and tested. The second phase consists of fabrication and test of a complete two-dimensional truss. The design, analysis, fabrication and test procedures are discussed in this paper which also includes the results of successful tests on the elements and center member conducted under the first phase of the NASA program.
Engler, E.↗
Vacuum-ultraviolet spectrum of neutral boron /B I/.
Use of a hollow-cathode light source to produce the vacuum-ultraviolet spectrum of B I. One transition is resolved, and four transitions have been remeasured to a higher accuracy than previously because of the sharper lines emitted by the hollow-cathode light source. A revised value for one transition term results from these measurements.-
Goorvitch, D.↗
Development of boron epoxy rocket motor chambers.
A 71 cm diameter 74 cm length boron/epoxy composite rocket motor chamber was designed based on the geometric configuration of the JPL Applications Technology Satellite titanium alloy apogee motor chamber. Because analyses showed large stress concentrations in the domes, the configuration was modified using the same basic constraints for openings and attachments. The rocket motor chamber was then fabricated by filament winding with boron/epoxy tape and hydrostatically tested to failure at 264 N/sq cm, 57.2 N/sq cm above the design value. Two more rocket motor chambers were fabricated with the same basic constraints, but shortened to 57.6 cm for a smaller propellant load. The first of these short chambers failed in proof because of filament winding fabrication difficulties. The second chamber was successfully fabricated and passed the hydrostatic proof test.
Jensen, W. M.↗
Boron--epoxy tubular structure members
Composite materials fabricate thin-walled tubular members which have same load-carrying capabilities as aluminum, titanium, or other metals, but are lighter. Interface between stepped end fitting and tube lends itself to attachments by primary as well as secondary bonding. Interlaminar shear and hoop stress buildup in attachment at end fitting is avoided.
Shakespeare, W. B. J.↗
The effect of boron concentration on radiation damage in silicon solar cells.
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Wilsey, N. D.↗
Experimental observations of tensile fracture in unidirectional boron filament reinforced aluminum sheet.
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Herring, H. W.↗
Development of advanced composite rocket motor chambers using boron and graphite fibers.
Four 71-cm-diameter rocket motor chambers were designed and fabricated with advanced composite materials. The first three chambers were filament wound from boron/epoxy tape, and the fourth from graphite/epoxy tape. The first boron/epoxy chamber was 74 cm in length and was successfully hydroburst tested. The other three chambers were 57.6 cm in length for a smaller propellant load. The first shortened boron/epoxy chamber failed in proof test as a result of fabrication deficiencies. The last boron/epoxy and the graphite/epoxy chambers were successfully proof tested.
Jensen, W. M.↗
The effect of thermal cycling on the mechanical properties of various aluminum alloys reinforced with unidirectional boron fibers
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Wright, M. A.↗
Changes in boron fiber strength due to surface removal by chemical etching
The effects of chemical etching on the tensile strength of commercial boron/tungsten fibers were investigated. Fibers with as-received diameters of 203, 143, and 100 micrometers were etched to diameters as small as 43 micrometers. The etching generally resulted in increasing fiber tensile strength with decreasing fiber diameter. And for the 203 micrometer fibers there was an accompanying significant decrease in the coefficient of variation of the tensile strength for diameters down to 89 micrometers. Heat treating these fibers above 1,173 K in a vacuum caused a marked decrease in the average tensile strength of at least 80 percent. But after the fibers were etched, their strengths exceeded the as-received strengths. The tensile strength behavior is explained in terms of etching effects on surface flaws and the residual stress pattern of the as-received fibers.
Smith, R. J.↗
The isotopic composition of galactic cosmic-ray lithium, beryllium, and boron
The isotopes of cosmic-ray Li, Be, and B near 100 MeV per nucleon have been measured with cosmic-ray telescopes on board the IMP-7 and IMP-8 satellites during 1973 and 1974. The measured isotopic abundances provide a stringent test for models of interstellar propagation and solar modulation. It is found that the isotopic abundances can be explained using a steady-state interstellar propagation model with a 5-g/sq cm leakage mean free path. These results, taken along with Be-10 abundance measurements, indicate a longer lifetime for cosmic rays than that predicted by the usual assumption of an average interstellar density of 1 to 3 atoms per cu cm.
Garcia-Munoz, M.↗
The absorption spectrum of neutral boron, B I
The absorption spectrum of B I has been studied in the 900-2000 A wavelength range by the flash pyrolysis technique. Transitions were observed from both the 2s(2)2p 2P ground state and the 2s2p2 4P metastable state. Five new quartet terms have been identified, with improved values obtained for two previously identified terms. A method of focusing has been developed, allowing the Ballofet-Romand-Vodar (1961) source to be used as a source of single-shot continuum in the lower wavelengths (300-1200 A) of the normal incidence region.
Roig, R. A.↗
Stark shift in ionized boron
Stark shift of the B II line at 3451 A due to plasma microfields was measured in a luminous shock tube. Line profiles, photographically recorded in second order, were compared with closeby wavelength fiduciaries from low-pressure rare-gas lamps. Electron densities for each exposure were found by fitting H-beta profiles to theoretical line shapes. Results, estimated reliable to 25-30%, are compared with theoretical predictions.
Miller, M. H.↗
The abundance of boron in Vega and Sirius
High-resolution (0.05 A) Copernicus observations of the 1362.46-A B II resonance line in Sirius and Vega are analyzed. In Vega, this line is found to be strong, broad, asymmetric, and blended with another line; it is not observed in Sirius. Angular velocities of 18-20 km/s for Vega and 10 km/s for Sirius are determined. A search for subordinate lines of B II reveals no such features in the Sirius spectrum and the possible weak presence of two unblended lines in that of Vega. The cause of the asymmetry of the B II blend in Vega is investigated, line-profile calculations are performed for Sirius, and the B content of Vega is obtained by means of an LTE synthesis of the B II blend as well as a non-LTE computation of the B II line alone. It is concluded that Sirius is deficient in B relative to Vega by a factor of at least 20. The Be abundances of both stars are also examined in relation to the galactic-cosmic-ray spallation theory for the origin of light elements.
Praderie, F.↗