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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Effect of hot isostatic pressing on the properties of sintered alpha silicon carbide

Two lots of alpha silicon carbide were isostatically hot-pressed under 138 MPa for 2 h in Ar at temperatures up to 2200 C. Nearly theoretically dense specimens resulted. Hot isostatic pressing increased both room-temperature strength and 1200 C strength, and resulted in improved reliability. One lot of material which was pressed at 2200 C showed increases of about 20 percent in room-temperature strength and about 50 percent in 1200 C flexural strength; the Weibull modulus improved about 100 percent.

Watson, G. K.↗
NASA NTRS1986

Investing in a Large Stretch Press

Press for forming large aluminum parts from plates provides substantial economies. Study assessed advantages and disadvantages of investing in large stretch-forming press, and also developed procurement specification for press.

Choate, M.↗
NASA NTRS1985

NASA/MSFC Large Stretch Press Study

The purpose of this study was to: A. assess and document the advantages/disadvantages of a government agency investment in a large stretch form press on the order of 5000 tons capacity (per jaw); B. develop a procurement specification for the press; and C. provide trade study data that will permit an optimum site location. Tasks were separated into four major elements: cost study, user survey, site selection, and press design/procurement specification.

Choate, M. W.↗
NASA NTRS1960

The Hot-Pressing of Hafnium Carbide (Melting Point, 7030 F)

An investigation was undertaken to determine the effects of the hot-pressing variables (temperature, pressure, and time) on the density and grain size of hafnium carbide disks. The purpose was to provide information necessary for the production of high-density test shapes for the determination of physical and mechanical properties. Hot-pressing of -325 mesh hafnium carbide powder was accomplished with a hydraulic press and an inductively heated graphite die assembly. The ranges investigated for each variable were as follows: temperature, 3500 to 4870 F; pressure, 1000 to 6030 pounds per square inch; and time, 5 to 60 minutes. Hafnium carbide bodies of approximately 98 percent theoretical density can be produced under the following minimal conditions: 4230 F, 3500 pounds per square inch, and 15 minutes. Further increases in temperature and time resulted only in greater grain size.

Sanders, William A.↗
NASA NTRS1987

AC-67 Press Conference

On March 26, 1987, after the launch of an Atlas/Centaur rocket with a payload of a Navy Communications Satellite, a problem developed and the rocket was lost. This videotape is a press conference held to review the incident. Mr. John Gibb, the Atlas-Centaur Program Manager at Lewis Research Center, opens the press conference with a statement that reviews the situation, and what is known about the accident. He reviews the constraints to launch and explains that to the best of his knowledge there was no violation of these constraints. He further states that a review panel will investigate the circumstances and make recommendations. The press conference is then opened up to questions. Most of the questions concern the weather conditions and the existence of lightning in the area. The Air Force representative, Colonel John Albrook, is asked if the loss of the satellite would pose any problems. He answers that there were several satellites performing the role for which this satellite was slated, and that these were still healthy, and capable of continuing for a considerable length of time.

Source record↗
NASA NTRS2015

Kennedy Space Center Press Site (SWMU 074) Interim Measure Report

This report summarizes the Interim Measure (IM) activities conducted at the Kennedy Space Center (KSC) Press Site ("the Press Site"). This facility has been designated as Solid Waste Management Unit 074 under KSC's Resource Conservation and Recovery Act Corrective Action program. The activities were completed as part of the Vehicle Assembly Building (VAB) Area Land Use Controls Implementation Plan (LUCIP) Elimination Project. The purpose of the VAB Area LUCIP Elimination Project was to delineate and remove soil affected with constituents of concern (COCs) that historically resulted in Land Use Controls (LUCs). The goal of the project was to eliminate the LUCs on soil. LUCs for groundwater were not addressed as part of the project and are not discussed in this report. This report is intended to meet the Florida Department of Environmental Protection (FDEP) Corrective Action Management Plan requirement as part of the KSC Hazardous and Solid Waste Amendments permit and the U.S. Environmental Protection Agency's (USEPA's) Toxic Substance Control Act (TSCA) self-implementing polychlorinated biphenyl (PCB) cleanup requirements of 40 Code of Federal Regulations (CFR) 761.61(a).

Measures↗
NASA NTRS1970

Properties of Hot Pressed Titanium Alloy Powders for Cryogenic Applications.

Evaluation of strength and toughness of hot-pressed titanium alloy powders at room and at cryogenic temperatures. The purpose was to determine how the mechanical properties of solid bodies formed from powder would compare with wrought specimens of the same size and with the same chemical analysis. It was found that of five titanium powder-making processes investigated, only the Rotating Electrode Process (REP) was capable of producing ELI-grade titanium alloy powder. Blocks hot-pressed from spherical REP powders had tensile properties equivalent to or better than those obtained from wrought bar.

Friedman, G. I.↗
NASA NTRS1972

Deformation, recrystallization, strength, and fracture of press-forged ceramic crystals.

Sapphire and ruby were very difficult to press-forge because they deformed without cracking only in a limited temperature range before they melted. Spinel crystals were somewhat easier and MgO, CaO, and TiC crystals much easier to forge. The degree of recrystallization that occurred during forging (which was related to the ease and type of slip intersections) varied from essentially zero in Al2O3 to complete (i.e., random polycrystalline bodies were produced) in CaO. Forging of bi- and polycrystalline bodies produced incoherent bodies as a result of grain-boundary sliding. Strengths of the forged crystals were comparable to those of dense polycrystalline bodies of similar grain size. However, forged and recrystallized CaO crystals were ductile at lower temperatures than dense hot-pressed CaO. This behavior is attributed to reduced grain-boundary impurities and porosity. Fracture origins could be located, indicating that fracture in the CaO occurs internally as a result of surface work hardening caused by machining.-

Rice, R. W.↗
NASA NTRS1973

Crack toughness evaluation of hot pressed and forged beryllium.

Fracture toughness tests at room temperature were made on three-point loaded beryllium bend specimens cut from hot pressed block and a forged disk. These specimens had plane proportions conforming to ASTM E 399 and covered a thickness range of from 1/32 to 1/2 in. Two sets of bend specimens were tested, one having fatigue cracks and the other 0.5 mil radius notches. One objective of the investigation was the development of techniques to produce fatigue cracks in accordance with the procedures specified in ASTM E 399. This objective was achieved for the hot pressed material. In plane cracks were not consistently produced in the specimens cut from forged stock.

Jones, M. H.↗
NASA NTRS1979

A split sphere 60,000 ton press

A split sphere press which can have a total force of 60,000 tons applied to its exterior by a 0.55 GPa hydrostatic pressure vessel is described. The inner anvils are made of tungsten carbide and show considerable plastic deformation under load. Much greater pressures, in the 100 GPa range, are possible if diamond tipped anvils are used. Because of the uniformly loaded multi-anvil arrangement, the diamond tips can be maintained under a high degree of compressive load and therefore prevent fracture which may occur in a conventional opposed anvil arrangement. Press operation on CdS, ZnSe, ZnS, GaP, and BP samples is described, and their resistance versus external pressure on the sphere are plotted.

Wanagel, J.↗
NASA NTRS1982

Hot isostatically pressed manufacture of high strength MERL 76 disk and seal shapes

The feasibility of using MERL 76, an advanced high strength direct hot isostatic pressed powder metallurgy superalloy, as a full scale component in a high technology, long life, commercial turbine engine were demonstrated. The component was a JT9D first stage turbine disk. The JT9D disk rim temperature capability was increased by at least 22 C and the weight of JT9D high pressure turbine rotating components was reduced by at least 35 pounds by replacement of forged Superwaspaloy components with hot isostatic pressed (HIP) MERL 76 components. The process control plan and acceptance criteria for manufacture of MERL 76 HIP consolidated components were generated. Disk components were manufactured for spin/burst rig test, experimental engine tests, and design data generation, which established lower design properties including tensile, stress-rupture, 0.2% creep and notched (Kt = 2.5) low cycle fatigue properties, Sonntag, fatigue crack propagation, and low cycle fatigue crack threshold data. Direct HIP MERL 76, when compared to conventionally forged Superwaspaloy, is demonstrated to be superior in mechanical properties, increased rim temperature capability, reduced component weight, and reduced material cost by at least 30% based on 1980 costs.

Eng, R. D.↗
NASA NTRS1983

High temperature deformation of hot-pressed polycrystalline orthoenstatite

Artificial hot pressed polycrystalline samples were prepared from purified powder of Bamble, Norway, orthoenstatite, (Mg0.86Fe0.14)SiO3. The uniaxial creep behavior of the polycrystalline orthoenstatite was studied over stress ranges of 10-180 MPa and temperatures of 1500-1700 K (0.82-0.93 T sub m) under two different oxygen fugacities, namely equilibrium (Mo-MoO2 buffer) and a reducing (graphite heating element) atmosphere, respectively. An intergranular glassy phase of different compositions with a cavitational creep deformation were observed. In the Mo-MoO2 buffer atmosphere with PO2 approx. 10 to the minus 11 power - 10 to the minus 13 power atmospheres, the results of an analytical electron microscopy analysis indicate that the glassy phases are richer in Ca and Al due to the residual impurities after hot pressing. In the reducing atmosphere with an oxygen fugacity of PO2 approx. 10 to the minus 3 power - 10 to the minus 25 power atmospheres, the results of analytical electron microscopy analysis indicate that the glassy phase is almost pure silica with the presence of free iron precipitate on grain facets and at triple junctions due to the reduction of bulk materials.

Dehghan-Banadaki, A.↗
NASA NTRS1984

Bending strength studies on hot-pressed silicon carbide

The 4-point bending strength of 4 grades of hot-pressed SiC was determined at different temperatures. With a transgranular mode of fracture the values for bending strength are retained up to high temperatures. For intergranular fracture the decrease of strength is governed by subcritical crack growth. The intergranular fracture is caused by a high content of silicate glassy phase at the grain boundaries of hot-pressed SiC.

Kriegesmann, J.↗
NASA NTRS1985

Effect of speed and press fit on fatigue life of roller-bearing inner-race contact

An analysis was performed to determine the effects of inner ring speed and press fit on the rolling element fatigue life of a roller bearing inner race contact. The effects of the resultant hoop and radial stresses on the principal stresses were considered. The maximum shear stresses below the Hertzian contact were determined for different conditions of inner ring speed, load, and geometry and were applied to a conventional ring life analysis. The race contact fatigue life was reduced by more than 90 percent for some conditions when speed and press fit were considered. The depth of the maximum shear stress remained virtually unchanged.

Coe, H. H.↗
NASA NTRS1985

Fracture toughness of hot-pressed beryllium

This paper presents the results of an investigation into the fracture toughness, sustained-load flaw growth, and fatigue-crack propagation resistance of S200E hot-pressed beryllium at room temperature. It also reviews the literature pertaining to the influence of various factors on the fracture toughness of hot-pressed beryllium determined using fatigue-cracked specimens.

Lemon, D. D.↗
NASA NTRS1985

Hot isostatic pressing of ceramics

A mixture containing glass 70 to 95 and BN or B4C powder (0.1-10 microns) 5 to 30 vol. % is used as a secondary pressure medium in hot isostatic pressing of ceramics. Thus, Pyrex beads were mixed with 15% vol. BN powder (average diameter 2 microns), fused at 1400 deg for 2 h, cooled, crushed, and put into a graphite crucible. A Si3N4 sintered body was embedded in the powder, heated in vacuum at 1200 deg for 2 h, treated in a hot isostatic press furnace at 1700 deg and 1000 atm. for 1 h, and cooled to give a Si3N4 ceramic. It was easily separated from the crucible.

Honma, K.↗
NASA NTRS1987

Mechanical properties of high gradient and hot isostatically pressed PWA 1480

This program has been designed to evaluate the potential benefits to alloy 1480 material properties due to high thermal gradient casting, hot isostatic pressing, and alternative heat treatment. Alloy 1480 castings have been obtained from vendors representing the extremes of commercial casting thermal gradients. Quantitative characterization of the dendrite arm spacing (DAS) and pore distributions has been conducted. A hot isostatic pressing (HIP) schedule, which avoids the many pitfalls of single crystal HIP has been devised for alloy 1480. In addition, an alternate heat treatment for alloy 1480 has been devised which provides benefits in mechanical properties. The standard gradient cast test material is being evaluated in the standard heat treat condition as a baseline and in the HIP plus alternate heat treated condition. The fhigh gradient cast material is being evaluated in alternate heat treat and HIP plus alternate heat treated conditions. Evaluations focus on demonstration of the benefits due to the applied processes, especially in the area of cyclic life.

Fritzemeier, L. G.↗
NASA NTRS1989

Canning Of Powdered Metal For Hot Isostatic Pressing

Quality of specimen enhanced by improved canning process. Method developed for canning specimens for hot isostatic pressing. Specimen placed inside refractory-metal ring, then sandwiched between two refractory-metal face sheets. Assembly placed inside die, then positioned in vacuum hot press. Heated to set temperature at prescribed vacuum to burn off all of binder in specimen. Advantages: powder-metallurgy composite totally purged of binder sealed in can in single operation, maintains size, shape, and uniformity of specimen. Weld region does not recrystallize, and little possibility of cracking.

Juhas, John J.↗