Accession Number : AD0779053

Title :   Investigation of Ceramics for High-Temperature Turbine Vanes.

Descriptive Note : Final rept. 20 Mar-19 Dec 73,

Corporate Author : GENERAL ELECTRIC CORPORATE RESEARCH AND DEVELOPMENT SCHENECTADY N Y

Personal Author(s) : Prochazka,Svante ; Smith,Peter C.

Report Date : APR 1974

Pagination or Media Count : 76

Abstract : Large tubular crystals of alpha-SiC, which can become strength limiting, tend to grow during the hot-pressing boron containing beta-SiC powder. The exagerrated grain growth was controlled by several methods: Stabilization of beta-SiC by nitrogen; nucleation of alpha-SiC by seeding; and, decreasing the hot-pressing temperature by using SiC powders with increased sinterability. Nitrogen doping was achieved by the addition of either Si3N4 or BN and yields electrically conductive materials which are amenable to electro discharge machining. The hot-pressing of large billets of nitrogen-doped materials revealed that specimen thickness and the applied pressure are critical parameters which affect the final density. Pressure-less sintering was achieved in submicron beta-SiC powders by the addition of boron and carbon. Results of microstructural examination, room temperature and high temperature bend strength, creep and impact tests are presented. (Modified author abstract)

Descriptors :   *Silicon carbides, *Hot pressing, *Grain size, Sintering, Density, Boron, Nitrogen, Additives, Creep, Impact strength, Flexural strength, Gas turbines

Subject Categories : Ceramics, Refractories and Glass
      Jet and Gas Turbine Engines

Distribution Statement : APPROVED FOR PUBLIC RELEASE