High-Pressure Viewports for Infrared Systems. Phase 1. Germanium
Abstract
Spherical sectors fabricated from polycrystalline germanium can serve successfully as pressure-resistant windows in IR systems in the marine environment. Spherical sectors and included spherical angle withstood 100 pressure cycles from 0 to 20000 psi without cracking when tested hydrostatically in a compliant metallic mounting with an inclined seat protected by elastomeric gaskets. Nylon cloth-reinforced Neoprene and Kevlar-49-reinforced epoxy gaskets performed successfully provided that the bearing stress did not exceed 20000 psi for Neoprene and 60000 psi for epoxy gaskets. The average flexural and compressive short-term strengths of germanium under uniaxial loading were found to be in the 70000-to-15000-psi ranges, respectively. Germanium also exhibits static fatigue under sustained flexure loading in the marine environment. The static fatigue limit for sustained loading of 1000-hour duration in a seawater environment was found to be in the 8000-to-10000-psi range. Germanium was found to also to exhibit the Kaiser effect even though it is only a rather weak emitter of acoustic emissions under compressive loading. It appears that recording of acoustic emissions during a structural proof test could be incorporated into the quality assurance program for germanium lenses and windows where it would complement visual inspection for the presence of incipient cracks.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1980
- Accession Number
- ADA097089
Entities
People
- Jerry D. Stachiw