Download or read book Effect of CVD Tungsten and TaC Coatings on the Mechanical Behavior of SiC(C). written by and published by . This book was released on 1979 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 GN/sq M (280 Ksi) to respectively 1.05 GN/sq M (150 Ksi) and 1.6 GN/sq 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.