Authors

AriIsaac Sagiv

Type

Text

Type

Thesis

Advisor

Christopher M. Weyant. | Sanjay Sampath | Dilip Gersappe.

Date

2011-08-01

Keywords

Materials Science -- Energy | Coatings, HVOF, Plasma Spray, Silicate, Silicon Carbide, Thermal Spray

Department

Department of Materials Science and Engineering

Language

en_US

Source

This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree.

Identifier

http://hdl.handle.net/11401/71685

Publisher

The Graduate School, Stony Brook University: Stony Brook, NY.

Format

application/pdf

Abstract

Environmental barrier coatings are a key technology for implementing ceramics in high- temperature, high-moisture environments. One such ceramic, silicon carbide, is a material that can be used in gas turbines. However, silicon carbide oxidizes into silicon dioxide with exposure to oxygen, carbon dioxide, and water vapor and would normally provide protection for the silicon carbide. However, silicon dioxide volatilizes in a gas turbine environment, which leads to the degradation of its mechanical properties, making it unfit for use in a gas turbine. Materials like yttria-monosilicate and barium-strontium doped aluminosilicate (BSAS) both have good environmental coating properties. However, sintered yttria-monosilicate does not bond well to silicon carbide, and thermally sprayed BSAS transforms very slowly from a metastable hexacelsian phase to the desired celsian phase that is necessary for it to bond well to silicon carbide. Coatings of these materials have been produced by plasma spray with some additional work using HVOF. Phase identification has been done by x-ray diffraction, and microstructural analysis has been done using scanning electron microscopy.

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