R.H. Zee

Auburn University

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Bryan A. Chin

University of California, San Diego

E.P. George

Ruhr University Bochum

J.W. Cohron

Oak Ridge National Laboratory

Yo Ozaki

Auburn University

Paul E. Thoma

Johnson Controls (United States)

J.F. Watters

Atomic Energy (Canada)

A. Rogerson

Amec Foster Wheeler (United States)

C. Patuwathavithane

Auburn University

M. F. Rose

Naval Surface Warfare Center

L. Heatherly

Oak Ridge National Laboratory

Cooperative Institutions

Auburn University

Atomic Energy (Canada)

Oak Ridge National Laboratory

Canadian Nuclear Laboratories

Argonne National Laboratory

University of Alabama

Northwestern Polytechnical University

University of Science and Technology Beijing

University of Wisconsin–Madison

Los Alamos National Laboratory

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Ballistic response of polymer composites

Polymer Composites (1991)

R.H. Zee C. J. Wang Andrew S. Mount B. Z. Jang Cheng-Ta Hsieh

Abstract A new microvelocity sensor unit was developed to measure the instantaneous velocity of a projectile during the penetration process. The concept of this device is based on the induced current generated in a coil resulting from the passage of a magnet. A special digital circuit was designed to yield a spatial resolution of better than 2.5 mm by elimiating the problem of signal overlap. The time delays obtained from these signals were used to determine the slowing down or energy loss of a high velocity projectile. A light gas gun was used to propel aluminum projectiles to velocities up to 320 m/s. Energy loss of these high velocity projectiles in composites reinforced with polyethylene, polyester, and graphite fabrics was investigated. Two distinct energy loss mechanisms were detected, one due to the actual fracture process and the other to the generation of frictional heat. Extensive delamination was observed in the more ductile PE and PET composites, but not in graphite. Low velocity instrumented drop‐tower impact tests were also conducted, using identical specimens and similar impact geometries.

Penetration (warfare)

Light-gas gun

10.1002/pc.750120310

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Citations (16)

A filament wound carbon-carbon composite for impact shell application

AIP conference proceedings (2000)

R.H. Zee

The performance and safety of the radioisotope power source depend in part on the thermal and impact properties of the materials used in the general purpose heat source (GPHS) through the use of an impact shell, thermal insulation and an aeroshell. Within the aeroshell are two graphite impact shells, made of fine-weave pierced-fabric (FWPF) that encapsulate four iridium alloy clad isotopic fuel pellets and provides impact protection for the clad. Impact studies conducted at Los Alamos National Laboratory showed that impact shells typically fractured parallel to their longitudinal axis. The objective of this effort is to develop new impact shell concepts with improved performance. An effort to develop alternative carbon-carbon composites for the graphite impact shell was conducted. Eight braided architectures were examined in this study. The effects of the number of graphitization cycles on both the density and circumferential strength of these braided structures were determined. Results show that a filament wound carbon-carbon composite possesses the desired density and circumferential strength important to GPHS.

Carbon fibers

10.1063/1.1290970

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Reactivity of Refractory Carbides with Hot Hydrogen

AIP conference proceedings (1994)

J.W. Cohron Yo Ozaki Bryan A. Chin R.H. Zee Mohamed S. El‐Genk

The degradation of ceramic carbides (TaC, WC, and NbC) for thermal nuclear propulsion systems induced by hydrogen at high temperatures was investigated. Experiments were conducted in vacuum (control experiments) and hydrogen for temperatures ranging from 1000 K to 1600 K. Weight loss, microstructure and phase analyses were performed to correlate the degradation processes in these materials. No hydride formation was observed in any of the specimens when conducted in the presence or absence of hot hydrogen. Oxides were formed in the hydrogen and vacuum runs for TaC. However, oxidation of TaC ceased above 1250 K in the presence of hydrogen. Hydrogen had virtually no effect on the crystal structure of WC or NbC. Weight loss in NbC was enhanced by the presence of hot hydrogen whereas the contrary was observed in TaC. The degradation processes were found to depend strongly on materials and experimental conditions. High temperature emissivities of TaC, WC, and NbC were measured by means of single‐wavelength and dual‐wavelength radiation thermometry and these values were found to be higher than previously reported.

Degradation

10.1063/1.2950291

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Citations (4)

Technique to determine solute diffusion coefficient and partial pressure simultaneously

Review of Scientific Instruments (1985)

R.H. Zee J.F. Watters R. D. Davidson

A simple technique to measure simultaneously the diffusion coefficient and the partial vapor pressure of a solute in a homogeneous solid solution is presented. The analysis is based on the mathematical solution of the diffusion equation for a cylindrical system with a solute loss term at the cylinder surface. The magnitude of the loss term is proportional to the solute concentration at the surface. Three zirconium rods, one with 3 at. % Sn, one with 5 at. % Sn, and one with 4 at. % Ti, were treated in vacuum at 1875 K for 7, 5, and 2.5 h, respectively. Results from these specimens indicate that Sn and Ti both diffuse via a vacancy mechanism in β-Zr. Also, the Sn–Zr bonds appear to be much stronger than the Sn–Sn bonds, whereas the Ti–Zr bonds seem to be a little weaker than the Ti–Ti bonds.

Partial pressure

10.1063/1.1138115

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Citations (3)

Hypervelocity impact study: The effect of impact angle on crater morphology

NASA STI/Recon Technical Report N (1993)

Gary D. Crawford David Hill Frank E. Rose R.H. Zee Steve Best

The Space Power Institute (SPI) of Auburn University has conducted preliminary tests on the effects of impact angle on crater morphology for hypervelocity impacts. Copper target plates were set at angles of 30 deg and 60 deg from the particle flight path. For the 30 deg impact, the craters looked almost identical to earlier normal incidence impacts. The only difference found was in the apparent distribution of particle residue within the crater, and further research is needed to verify this. The 60 deg impacts showed marked differences in crater symmetry, crater lip shape, and particle residue distribution. Further research on angle effects is planned, because the particle velocities for these shots were relatively slow (7 km/s or less).

Hypervelocity

Particle (ecology)

Source

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Diffusion and chemical activity of Zr-Sn and Zr-Ti systems

Physical review. B, Condensed matter (1986)

R.H. Zee J.F. Watters R. D. Davidson

A modified evaporation method was used to determine the diffusion coefficients and the emission rates of Sn and Ti in Zr-Sn and Zr-Ti, respectively, at temperatures between 1605 and 1970 K. Results show that both Sn and Ti diffuse in their respective alloys via a vacancy mechanism. Comparison with data in the literature reveals that the activation energy for diffusion of Sn in Zr-Sn, with Sn content between 3 and 5 at.? is relatively constant from 1200 to 1970 K. From the measured emission rates, values of 103 and 98 kcal/mol were obtained for the enthalpies of sublimation for Sn and Ti in their alloys. With a comparison of the solute vapor pressures with those of the pure elements, partial molar free energies, entropies, and enthalpies for the two systems were determined in the temperature range investigated. The Zr-Sn system shows a very large negative heat of formation (-33 kcal/mol) whereas the Zr-Ti system behaves quite ideally, in agreement with phase-diagram predictions.

Sublimation

Atmospheric temperature range

10.1103/physrevb.34.6895

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Citations (19)

Creep, thermal-cyclic and tensile properties of Nb1Zr to stainless steel transition joints

Journal of Nuclear Materials (1994)

S. Chen Wei Yu R.H. Zee Bryan A. Chin

Ductility (Earth science)

10.1016/0022-3115(94)91091-x

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Citations (1)

Irradiation growth of zirconium single crystals: A review

Journal of Nuclear Materials (1988)

G.J.C. Carpenter R.H. Zee A. Rogerson

10.1016/0022-3115(88)90087-6

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Citations (94)

Infrared thermographic analysis of polymer composites during ballistic impact

Review of Scientific Instruments (1992)

Cheng-Ta Hsieh S. Nagarajan R.H. Zee

Heat is deposited in a target material when it is impacted by a projectile. The feasibility of using an infrared thermographic system to measure the surface temperature profile of composite materials under ballistic impact was demonstrated. Three types of composites were used in this instrumentation study to illustrate the effectiveness and limitation of this technique. The resolution of temperature was found to be better than ±1 K. The total temperature rise in the materials during impact can be attributed to the deformation required to perforate the material as well as frictional heat produced between the projectile and the hole. The heat deposited was calculated based of the temperature profiles. The relative contribution of the frictional effect to the total energy absorption was evaluated using a sequential shot technique. Effects of material properties and impact parameters on the peak temperature and heat deposition were determined. Graphite and PE composites are more effective than Kevlar composite in dissipating heat during the ballistic impact penetration process due to their higher thermal conductivity. The correlation between heat dissipation and extent of damage in composites was also investigated.

Ballistic Impact

Kevlar

Ballistics

Penetration (warfare)

Thermography

10.1063/1.1143153

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Citations (3)

Interdiffusion of rhenium and poco graphite

AIP conference proceedings (1998)

Jinglong Li R.H. Zee

Graphite is being considered as the prime candidate as the energy storage material for space propulsion. One of the anticipated problems is the loss of graphite at high temperature. Rhenium has been proposed as a diffusion barrier for graphite to prevent excessive loss of the material. However, the mutual diffusion of graphite and rhenium has not been measured, and much of the data is based on extrapolation with high degree of error. A technique to study the interdiffusion of rhenium and carbon without a marker was developed based on Rutherford Backscattering Spectroscopy (RBS) technique. The graphite samples used in this experiment were Poco graphite purchased from Unocal. The specimens used for rhenium deposition were in the form of round discs cut from a 25.4 mm diameter bar. The round discs were mechanically polished down to a thickness of 2 mm. A thin layer of rhenium was then sputter-deposited onto the polished Poco graphite surface using a RF sputtering system. The deposition rate was determined to be 10 nm/min at a RF power of 20 Watts and an Ar gas pressure of 2.67 Pa. The samples coated with rhenium were given different diffusion anneals at temperatures between 1373 K and 2273 K in a vacuum electron beam furnace. The diffusion constants were obtained by fitting the RBS profiles with appropriate diffusion equations. The diffusion constants for rhenium in Poco graphite range from 9×10−18 m2/s at 1373 K to 7×10−17 m2/s at 2273 K, whereas the diffusion constants for carbon in rhenium films range from 6×10−17 m2/s at 1373 K to 9×10−16 m2/s at 2273 K. Both Arrhenius plots of rhenium in graphite and carbon in rhenium clearly show a change in the slope with temperature. This feature indicates that there are two diffusion mechanisms involved. At lower temperatures, rhenium atoms diffuse along the open pores in Poco graphite, whereas at temperatures above 2073 K diffusion of rhenium through graphite lattice becomes dominant. Similarly, the carbon atoms diffuse along grain boundaries of rhenium at lower temperature. Diffusion of carbon atoms through rhenium lattice becomes important at temperatures above 1773 K.

10.1063/1.54823

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Citations (2)