CHEMICAL VAPOR DEPOSITED MATERIALS FOR ELECTRON TUBES.
Quarterly rept. no. 6, 15 Aug-14 Nov 66,
RAYTHEON CO WALTHAM MA RESEARCH DIV
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This program was established to investigate chemical vapor deposition as a method of producing materials or coatings for use in vacuum electron devices and microwave tubes. Isotropic CVDBN has been deposited upon tungsten wire for use as a heater coating. The tungsten was brittle after the deposition. It is expected that W-Re wire will remain ductile after deposition. Applications of CVDBN in electron devices require reliable joining methods. Ti, in conjunction with Cu or Ag-Cu, bonds to BN. Isotropic CVDBN also seals readily to borosilicate glasses. Dense, isotropic CVDBN deposited at a temperature above 1850 C showed no measurable change in weight or appearance after 72 hrs immersion in boiling water. Its dc dielectric strength was 9 kVmil. Silicon nitride deposited in thin layers on CVDBN is not damaged by thermal cycling between RT and 1000 C either in air or dry hydrogen. Some problems have been encountered in fabricating microwave windows, but these problems have been solved.
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