Accession Number : AD0477126

Title :   CHEMICAL VAPOR DEPOSITED MATERIALS FOR ELECTRON TUBES.

Descriptive Note : Quarterly rept. no. 2, 15 Aug-14 Nov 65,

Corporate Author : RAYTHEON CO WALTHAM MASS RESEARCH DIV

Personal Author(s) : Steele ,S. R. ; Pappis ,J. ; Ellis ,R. ; Hagen ,L. ; Schilling,H.

Report Date : JAN 1966

Pagination or Media Count : 46

Abstract : Experiments were continued with two methods of producing CVD BN, one resulting in a product with isotropic properties, the other with anisotropic properties. Eight process runs, whose objective was to produce thick samples of anisotropic CVD BN were made. An over-all improvement in the lateral and axial distribution of the material over the substrate was obtained, and the relative module size was reduced. Even so, this material is considerably more difficult to fabricate than is isotropic CVD BN. Four process runs with deposition temperatures ranging from 1500 to 1800 C were made to produce isotropic CVD BN to provide samples of property measurements. Samples of CVD silicon nitride have been prepared in thicknesses of 0.100 inch. CVD BN suffers no measurable weight change in dry N2 at temperatures up to 1300 C. It does display a slow weight loss in wet N2, and in wet and dry air at temperatures above 800 C, and also in boiling water. The electrical resistivity of isotropic BN ranges from above 10 to the 15th power ohm cm at room temperature to 10 to the 6th power ohm cm at 1350 C, making it one of the best high temperature insulating materials available. The surface resistance of CVD BN at 100% relative humidity is about that of a standard alumina window material. Hermetic seals have been made between tungsten and isotropic BN using titanium cored-silver-copper eutectic solder. (Author)

Descriptors :   (*ELECTRON TUBES, PROCESSING), (*VAPOR PLATING, COATINGS), FLEXURAL STRENGTH, CERAMIC MATERIALS, BORIDES, CARBIDES, NITRIDES, BORON ALLOYS, ZIRCONIUM COMPOUNDS, HAFNIUM COMPOUNDS, TITANIUM COMPOUNDS, ZIRCONIUM ALLOYS, SILICON ALLOYS, ISOTROPISM, ANISOTROPY, THERMAL SHOCK, THICKNESS, ELECTRICAL RESISTANCE, HUMIDITY, HERMETIC SEALS, SOLDERING ALLOYS, TITANIUM, SILVER, COPPER, PYROLYTIC GRAPHITE, DEGASIFICATION, ELECTRON IRRADIATION

Subject Categories : Electrical and Electronic Equipment
      Ceramics, Refractories and Glass

Distribution Statement : APPROVED FOR PUBLIC RELEASE