Engineering topics

Zee, R. H.

Publications and source records attributed to Zee, R. H..

5 records

NASA NTRS1992

Chemical compatibility of cartridge materials

The objectives were to determine the chemical compatibility of titanium-zirconium-molybdenum (TZM) with GaAs and CdZnTe, and Inconel with HgCdTe and HgZnTe. At the present time, no other studies regarding the compatibility of these crystal components and their respective cartridge materials have been performed. This study was to identify any possible problems between these materials to insure proper containment of possibly hazardous fumes during crystal growth experiments. In this study, the reaction zone between the materials was studied and the amount of degradation to the system was measured. Detailed results are presented.

Ambrose, Bryan↗

NASA NTRS1992

Infrared thermographic analysis of polymer composites during ballistic impact

An infrared thermographic system was used to measure the surface temperature profile of composite materials under ballistic impact. The heat deposited was calculated based on the temperature profiles. The extent of damage induced in the materials was determined qualitatively from the measured data. The relative contribution of frictional heat to total energy absorption was evaluated, and the effect of the shape of the projectile on the extent of damage and temperature distribution in the composites was examined. The results show that graphite and polyethylene composite are more effective than Kevlar composite in dissipating heat during the ballistic impact penetration process due to their higher thermal conductivity.

Hsieh, C. Y.↗

NASA NTRS1992

Momentum distribution in debris cloud during hypervelocity impact

The long term operation of the Space Station Freedom requires a scheme to protect it from high velocity impacts by both man-made particles and micrometeor fragments. One such scheme is the use of metal plates to serve as shields against such orbital debris. These 'bumper' plates, as they are referred to, serve to break up any incident particle and redistribute its momentum over a larger area. It is therefore necessary to determine the momentum distribution within the debris cloud produced by such collisions in order to evaluate a materials effectiveness at accomplishing this task. This paper details the design and development of an innovative device which has made this possible. Momentum profiles were obtained for a series of test conditions. Total momentum values in the debris cloud were then calculated from these profiles. These results indicated that a momentum amplification exists with a multiplication factor of between 2 and 3. Thus the role of the bumper to serve as a means for momentum redistribution and not reduction was verified.

Lemaster, P.↗

NASA NTRS1991

Chemical compatibility of cartridge materials

This twelve month progress report deals with the chemical compatibility of semiconductor crystals grown in zero gravity. Specifically, it studies the chemical compatibility between TZM, a molybdenum alloy containing titanium and zirconium, and WC 103, a titanium alloy containing Niobium and Hafnium, and Gallium arsenide (GaAs) and Cadmium Zinc Tellurite (CdZnTe). Due to the health hazards involved, three approaches were used to study the chemical compatibility between the semiconductor and cartridge materials: reaction retort, thermogravimetric analysis, and bulk cylindrical cartridge containers. A scanning electron microscope with an energy dispersive X-ray analyzer was used to examine all samples after testing. The first conclusion drawn is that reaction rates with TZM were not nearly as great as they were with WC 103. Second, the total reaction between GaAs and WC 103 was almost twice that with TZM. Therefore, even though WC 103 is easier to fabricate, at least half of the cartridge thickness will be degraded if contact is made with one of the semiconductor materials leading to a loss of strength properties.

Wilcox, Roy C.↗

NASA NTRS1990

Response of polymer composites to high and low velocity impact

The present investigation of fiber-reinforced polymer matrix composites' impact characteristics employed a drop tower for the low-velocity impact case and a novel, projectile instantaneous velocity-measuring sensor for high-velocity impact. Attention was given to the energy loss of projectiles in composites reinforced with polyethylene, kevlar, and graphite. Two distinct energy-loss mechanisms are noted, the first of which is due to the actual fracture process while the other is due to the generation of friction heat. The drop-tower impact-test results furnish the strain-rate dependence of the energy loss.

Hsieh, C. Y.↗