Advanced and precise manufacturing is presented for two key components: a compressor and a turbine impeller (Ø 20 mm) for an ultra miniature gas turbine system as fuel-based power generation system. The total system fits in a cylinder with a diameter of 110 mm and a length of 120 mm. At this scale, major components such as turbine and compressor are subjected to challenging requirements such as high rotational speed (500,000 rpm), high turbine inlet temperature (1,200 K) and efficiency. The choices of material and manufacturing technique are critical. The components must endure the operational requirements and should be fabricated in high accuracy. In order to withstand the high centrifugal stress, a high-strength titanium alloy is used for the compressor. Using micro-milling, a three-dimensional complex and accurate structure is obtained. The turbine is made of a Si3N4–TiN ceramic composite to sustain the combination of elevated stress and temperature. A scrupulously developed process chain combines electrical discharge machining and grinding as manufacturing processes, which not only just preserve the surface integrity and the related material strength but also provide an adequate dimensional and geometrical accuracy.
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