Failure analysis of glass-ceramic insulators of shock tested vacuum (neutron) tubes

Technical Report · Mon Aug 25 04:00:00 EDT 1980

DOI:https://doi.org/10.2172/5199074· OSTI ID:5199074

Spears, R. K.

Eight investigative techniques were used to examine the glass-ceramic insulators in vacuum (neutron) tubes. The insulators were extracted from units that had been subjected to low temperature mechanical shock tests. Two of the three units showed reduced neutron output after these tests and an insulator on one of these two was cracked completely through which probably occurred during shock testing. The objective of this study was to determine if any major differences existed between the insulators of these tubes. After eight analyses, it was concluded that no appreciable differences existed. It appeared that cracking of the one glass-ceramic sample was initiated at inner-sleeve interface voids. For this sample, the interface void density was much higher than is presently acceptable. All insulators were made with glass-ceramic having a Na/sub 2/O content of 4.6 wt%. An increased Na/sub 2/O content will cause an increase in the coefficient of expansion and will reduce the residual stress level since the molybdenum has a higher coefficient of thermal expansion than the insulator. Thus, it is believed that a decrease in interface voids and an increase in Na/sub 2/O should aid in reduced cracking of the insulator during these tests.

• Research Organization: General Electric Co., St. Petersburg, FL (USA). Neutron Devices Dept.
• DOE Contract Number: AC04-76DP00656
• OSTI ID: 5199074
• Report Number(s): GEPP-TIS-508
• Country of Publication: United States
• Language: English

Related Subjects

07 ISOTOPE AND RADIATION SOURCES
070201* -- Radiation Sources-- Design
Fabrication & Operation
ALKALI METAL COMPOUNDS
CERAMICS
CHALCOGENIDES
CRACKS
ELECTRICAL EQUIPMENT
ELECTRICAL INSULATORS
EQUIPMENT
FAILURES
GLASS
IMPACT SHOCK
NEUTRON SOURCES
OXIDES
OXYGEN COMPOUNDS
PARTICLE SOURCES
RADIATION SOURCES
RESIDUAL STRESSES
SODIUM COMPOUNDS
SODIUM OXIDES
STRESSES