Reflood Investigation of Fuel Assemblies Based on Analysis of High-Temperature Integral Experiments

Abstract Supersonic aircraft in the Mach 3 range have increased temperature requirements for many materials of construction. One of the most critical problem areas is the integral fuel tank where state-of-the-art elastomeric sealants no longer meet those requirements. New sealants resistant to hydrocarbon fuels at temperatures in excess of 500° F are urgently needed. A high temperature integral fuel tank filleting sealant has been developed based on a mixture of high and low molecular weight hydrofluoroearbon polymers. This sealant has a solids content of 85 per cent and cures at modest temperatures. It is a one component system stable for several weeks at ambient temperatures and for longer periods if refrigerated. The sealant exhibits good room temperature and high temperature mechanical properties both before and after aging in hydrocarbon fuel and fuel vapor at temperatures up to 500° F. A typical formulation showed an increase in tensile strength and better than 50 per cent retention of elongation after 1000 continuous hours exposure to fuel vapor at 500° F. Adhesion to metal substrates is good and samples have resisted rupture and loss of adhesion when pressurized at 500° F for 1000 hours. This is only an interim solution to the critical fuel tank sealant problem in Mach 3 aircraft. Research is continuing to improve its useable life and to eliminate a possibly serious corrosion problem with titanium substrates. It must be emphasized, however, that sealants based on hydrofluorocarbons, fluorosilicones, and other available elastomers can at best provide interim solutions to the high temperature sealant problems and that new base polymers, such as the triazine and polyether elastomers currently being developed by the Air Force Materials Laboratory, are needed to provide sealants which completely meet requirements.

Download Full-text

Computational study of the influence of some systematic factors on the fuel temperature in a very high temperature gas-cooled reactor with prismatic fuel assemblies

Physics of Atomic Nuclei ◽

10.1134/s1063778811140079 ◽

2011 ◽

Vol 74 (14) ◽

pp. 1921-1929 ◽

Cited By ~ 1

Author(s):

A. A. Sedov ◽

A. A. Frolov

Keyword(s):

High Temperature ◽

Computational Study ◽

Fuel Temperature ◽

Fuel Assemblies ◽

Very High ◽

High Temperature Gas

Download Full-text

Influence of Thermo-Mechanical Processing on the Microstructure of Beryllia Dispersed Nickel Alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071363 ◽

1973 ◽

Vol 31 ◽

pp. 184-185

Author(s):

M.S. Grewal ◽

S.A. Sastri ◽

N.J. Grant

Keyword(s):

High Temperature ◽

Nickel Alloys ◽

Thermomechanical Processing ◽

Cold Work ◽

High Temperature Strength ◽

Strengthening Effect ◽

Mechanical Processing ◽

Uniform Dispersion ◽

Oxide Particles ◽

Nickel Base

Currently there is a great interest in developing nickel base alloys with fine and uniform dispersion of stable oxide particles, for high temperature applications. It is well known that the high temperature strength and stability of an oxide dispersed alloy can be greatly improved by appropriate thermomechanical processing, but the mechanism of this strengthening effect is not well understood. This investigation was undertaken to study the dislocation substructures formed in beryllia dispersed nickel alloys as a function of cold work both with and without intermediate anneals. Two alloys, one Ni-lv/oBeo and other Ni-4.5Mo-30Co-2v/oBeo were investigated. The influence of the substructures produced by Thermo-Mechanical Processing (TMP) on the high temperature creep properties of these alloys was also evaluated.

Download Full-text

Application of TEM to Deformation, Wear, and Fracture of Ceramics

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100052377 ◽

1974 ◽

Vol 32 ◽

pp. 472-473

Author(s):

B. J. Hockey

Keyword(s):

Wear Resistance ◽

High Temperature ◽

Mechanical Behavior ◽

Brittle Materials ◽

High Temperature Strength ◽

Wide Range ◽

Corrosive Environments ◽

Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

Download Full-text

Lattice Imaging of Grain Boundaries in Ceramics

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100078171 ◽

1977 ◽

Vol 35 ◽

pp. 114-115

Author(s):

D. R. Clarke ◽

G. Thomas

Keyword(s):

Mechanical Properties ◽

High Temperature ◽

Silicon Nitride ◽

Grain Boundaries ◽

High Temperature Strength ◽

Current Interest ◽

Lattice Imaging ◽

Special Significance ◽

Structural Applications ◽

Refractory Ceramics

Grain boundaries have long held a special significance to ceramicists. In part, this has been because it has been impossible until now to actually observe the boundaries themselves. Just as important, however, is the fact that the grain boundaries and their environs have a determing influence on both the mechanisms by which powder compaction occurs during fabrication, and on the overall mechanical properties of the material. One area where the grain boundary plays a particularly important role is in the high temperature strength of hot-pressed ceramics. This is a subject of current interest as extensive efforts are being made to develop ceramics, such as silicon nitride alloys, for high temperature structural applications. In this presentation we describe how the techniques of lattice fringe imaging have made it possible to study the grain boundaries in a number of refractory ceramics, and illustrate some of the findings.

Download Full-text

Effect of Improved ThO2 Particle Dispersion in Nickel on High-Temperature Strength

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069211 ◽

1970 ◽

Vol 28 ◽

pp. 444-445

Author(s):

E. R. Kimmel ◽

H. L. Anthony ◽

W. Scheithauer

Keyword(s):

High Temperature ◽

Metal Matrix ◽

Oxide Particle ◽

Oxide Phase ◽

Dislocation Motion ◽

Particle Dispersion ◽

High Temperature Strength ◽

Strengthening Effect ◽

Oxide Particles ◽

The Stability

The strengthening effect at high temperature produced by a dispersed oxide phase in a metal matrix is seemingly dependent on at least two major contributors: oxide particle size and spatial distribution, and stability of the worked microstructure. These two are strongly interrelated. The stability of the microstructure is produced by polygonization of the worked structure forming low angle cell boundaries which become anchored by the dispersed oxide particles. The effect of the particles on strength is therefore twofold, in that they stabilize the worked microstructure and also hinder dislocation motion during loading.

Download Full-text