Accession Number:

ADA083395

Title:

Effect of CVD Tungsten and TaC Coatings on the Mechanical Behavior of SiC(C)

Descriptive Note:

Technical rept.

Corporate Author:

ARMY ARMAMENT RESEARCH AND DEVELOPMENT CENTER WATERVLIET NY LARGE CALIBER WEAPON SYSTEMS LAB

Personal Author(s):

Report Date:

1979-12-01

Pagination or Media Count:

50.0

Abstract:

Effects of the chemically-vapor-deposited tungsten and TaC coatings on the mechanical properties of silicon carbide carbon core filament have been investigated. In the temperature range of interest, because of the possible chemical interaction of tungsten with carbon rich silicon carbide phase on its surface and the columnar grain structure of the coating the filament was found to be embrittled. However, by controlling the initial nucleation of tungsten by adjusting the temperature, the direction of flow of reactants and filament speed, the degradation effect of the coating can be minimized. TaC coating did not decrease the strength of the filament, because it did not react with the filament and had fine grain structure. Coatings of tungsten and TaC decreased the 100 hr 2000 deg. F, rupture strength of the filament from 1.9 GNsq M 280 Ksi to respectively 1.05 GNsq M 150 Ksi and 1.6 GNsq M 240 Ksi. The tensile strength of the W coated filament was superior to that coated with TaC in the temperature range 1000-1500 deg. C. Thermal cycling room temperature - 1600 deg. C induced cracks in the TaC coating while W coating remained unaffected.

Subject Categories:

  • Coatings, Colorants and Finishes
  • Fabrication Metallurgy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE