Micro-gas turbine engine materials and structures

A program is underway to develop the technology for micro-gas turbine-generators capable of producing 50 W of electrical power in a package less than one cubic centimeter in volume. The initial goal of this project is to produce a turbine generator by micromachining single crystal silicon. The design and fabrication of such a device offers many challenges and opportunities in the field of materials and structures. The major challenges arise from the very high stress levels (approximately 1 GPa) required to achieve the necessary turbomachinery performance. The task is complicated by the need to achieve a good structural design within the constraints imposed by microfabrication processes. The major opportunities arise from the use of silicon at very small lengthscales. In particular, the use of microfabrication techniques offers the potential to control the processing-induced flaw size such that very high strengths can be obtained. In this paper the microengine materials and structural design efforts are described, with particular emphasis on the ramifications of the device's small size.