Corrosion problems in Ti/KC1O/sub 4/ loaded devices when subjected to humid environments

Conference · Tue Jan 01 04:00:00 EST 1980

OSTI ID:5031285

Massis, T. M.; Healey, J. T.; Huskisson, D. H.; Perkins, W. G.

A piston motor/igniter loaded with a Ti/KClO/sub 4/ pyrotechnic and sealed with a silicone adhesive exhibited serious corrosion problems during aging. Five 24-hour thermal cycles between room temperature and 71/sup 0/C at 90% relative humidity resulted in extensive surface corrosion of the Kovar pins and severe stress corrosion cracking of the Kovar pins in the vicinity of the bridgewire weld. No corrosion or cracking of the Nichrome bridgewire was observed. Similar results were observed after 60 days at 50% and 90% relative humidity at room temperature. Tests at ambient relative humidity and room temperature caused limited surface corrosion and no observable cracking. It was determined that these problems resulted from the combined presence of chlorine containing contaminants and atmospheric moisture. Chlorine was detected in both the surface corrosion product and the corrosion product in the subsurface cracks. The absence of reaction and/or morphological alteration of the Ti/KClO/sub 4/ at the pyrotechnic interface with the Kovar indicated the pyrotechnic was not involved in the corrosion reaction, and, hence, the chlorine was present in the surface contamination on the Kovar pins. The aging tests indicate that external moisture was involved in the corrosion reaction. Calculation and experimentation have shown the silicone adhesive used to seal these devices to be permeable to water vapor, and the moisture conditions inside the devices equilibrated with external conditions within a few hours. Corrosion and cracking could be solved by eliminating the source of moisture by hermetically sealing the devices. Tests of hermetically sealed units have confirmed this conclusion.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5031285
• Report Number(s): SAND-80-0964C; CONF-801048-6
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360604* -- Materials-- Corrosion
Erosion
& Degradation
AGING
ALKALI METAL COMPOUNDS
CHEMICAL REACTIONS
CHLORATES
CHLORINE
CHLORINE COMPOUNDS
CONTAMINATION
CORROSION
CORROSIVE EFFECTS
CRACKS
ELEMENTS
HALOGEN COMPOUNDS
HALOGENS
METALS
MOISTURE
NONMETALS
OXYGEN COMPOUNDS
POTASSIUM COMPOUNDS
STRESS CORROSION
THERMAL CYCLING
TITANIUM
TRANSITION ELEMENTS