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Microfabricated refractory ceramic structures for micro turbomachinery

IP.com Disclosure Number: IPCOM000128129D
Original Publication Date: 1999-Dec-31
Included in the Prior Art Database: 2005-Sep-15
Document File: 9 page(s) / 26K

Publishing Venue

Software Patent Institute

Related People

Lohner, Kevin Andrew: AUTHOR [+3]

Related Documents

http://theses.mit.edu:80/Dienst/UI/2.0/Describe/0018.mit.theses/1999-82: URL

Abstract

The NOT Microengine Project was initiated in 1995 as a joint effort between the Gas Turbine Laboratory (GTL) and Microsystems Technology Laboratory (MTL) to develop a MEMS-based micro-gas turbine engine. The thermodynamic requirements of powergenerating turbomachinery drive the design towards high rotational speeds and high temperatures. To achieve the specified performance requires materials with high specific strength and creep resistance at elevated temperatures. The thermal and mechanical properties of silicon carbide make it an attractive candidate for such an application. Silicon carbide as well as silicon-silicon carbide hybrid structures are being designed and fabricated utilizing chemical vapor deposition of relatively thick silicon carbide layers (10-100 um) over time multiplexed deep etched silicon molds. The silicon can be selectively dissolved away to yield high aspect ratio silicon carbide structures with features that are hundreds of microns tall.

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Page 1 of 9

 This record is the front matter from a document that appears on a server at MIT and is used through permission from MIT. See http://theses.mit.edu:80/Dienst/UI/2.0/Describe/0018.mit.theses/1999-82 for copyright details and for the full document in image form.

MICROFABRICATED REFRACTORY CERAMIC STRUCTURES FOR MICRO TURBOMACHINERY

by

KEVIN ANDREW LOHNER
Bachelor of Science in Materials Science and Engineering Purdue University, 1997 Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in AERONAUTICS AND ASTRONAUTICS

at the Massachusetts Institute of Technology

June 1999
SIGNATURE OF author: [[signature omitted]]

Department of Aeronautics and Astronautics

May 21, 1999

CERTIFIED BY: [[SIGNATURE OMITTED]]
S. Mark Spearing

Esther and Harold E. Edgerton Assistant Professor of Aeronautics and Astronautics Thesis Supervisor
ACCEPTED BY: [[SIGNATURE OMITTED]]

Jaime Peraire

Associate Professor of Aeronautics and Astronautics Chairman, Departmental Graduate Committee
ARCHIVES MASSACHUSETTS INSTITUTE OF TECHNOLOGY LIBRARIES JUL 15 1999

Massachusetts Institute of Technology Page 1 Dec 31, 1999

Page 2 of 9

Microfabricated refractory ceramic structures for micro turbomachinery

MICROFABRICATED REFRACTORY CERAMIC STRUCTURES FOR MICRO TURBOMACHINERY

by

KEVIN ANDREW LOHNER

Submitted to the Department of Aeronautics and Astronautics on May 2x,1999 in partial fulfillment of the requirements for the degree of Master of Science in Aeronautics and Astronautics

ABSTRACT

The NOT Microengine Project was initiated in 1995 as a joint effort between the Gas Turbine Laboratory (GTL) and Microsystems Technology Laboratory (MTL) to develop a MEMS-based micro-gas turbine engine. The thermodynamic requirements of powergenerating turbomachinery drive the design towards high rotational speeds and high temperatures. To achieve the specified performance requires materials with high specific strength and creep resistance at elevated temperatures. The thermal and mechanical properties of silicon carbide make it an attractive candidate for such an application. Silicon carbide as well as silicon-silicon carbide hybrid structures are being designed and fabricated utilizing chemical vapor deposition of relatively thick silicon carbide layers (10-100 um) over time multiplexed deep etched silicon molds. The silicon can be selectively dissolved away to yield high aspect ratio silicon carbide structures with features that are hundreds of microns tall.

Positive mold, negative mold, and hybrid Si/SiC processing techniques appear to be feasible microfabrication routes with potential for increasing microengine performance. Research has been performed to characterize the capabilities of these processes. Specimens fabricated in the course of this research show very good conformality and step coverage with a fine (=0.1 li m diameter) columnar microstructure. Surface roughness (Rq) of the films is on the order of 100 nm, becoming rougher with thicker d...