Hideaki Tsuru

Rapid prototyping and manufacturing by gelcasting of metallic and ceramic slurries

In this work an approach for rapid prototyping and manufacturing of metallic as well as ceramic parts is presented. By using Mold Shape Deposition Manufacturing (MoldSDM), a wax mold is fabricated which is filled with a slurry containing the final part material in powder form. The wax mold is manufactured by first decomposing the desired part geometry into machinable compacts. In a next step the mold is built up in a series of layers by machining either the wax or a sacrificial support material. The surface quality of the final mold is only limited by the abilities of the CNC machine. After casting a ceramic or metallic slurry, the wax mold is removed and the obtained green part debinded and sintered. In this work the mechanical and microstructural properties of the parts obtained by this method are presented. The materials which have been investigated are silicon nitride and stainless steels. Due to the high mold quality the process is suitable for a variety of applications in rapid prototyping and manufacturing where parts made of engineering materials are required.

Microscale Radial-Flow Compressor Impeller Made of Silicon Nitride: Manufacturing and Performance

A microscale, high-speed compressor impeller (12 mm diameter, 800,000 rpm) was tested for feasibility in regard to aerodynamic performance. The compressor was designed for application in a first-sized gas turbine generator. To survive high stresses at such high temperatures, the rotor was manufactured as a single turbine/compressor/shaft unit in silicon nitride, by the Mold SDM process. Performance testing was conducted in a cold-flow rig at reduced speed of 420,000 rpm. Results from a CFD code compared favorably to measured data at this speed. Extrapolation from test conditions to full design speed was accomplished by application of CFD applied at both speeds.

Rapid prototyping methods of silicon carbide micro heat exchangers

Abstract Conventional heat exchangers are mainly constructed of metal alloys. The manufacturing process of metal alloys usually requires assembling and joining techniques such as welding and diffusion bonding. In addition, the structures are limited to simple shapes due to the restrictions of the fabrication methods. This research focused on the manufacturing of compact heat exchangers made of high thermal-conductivity ceramic material, rather than on the performance of the devices. To achieve a high surface-volume ratio in heat exchangers, a strategy was adopted that fabricates miniaturized devices with a high shape complexity. This paper discusses an approach that uses a combination of mould shape deposition manufacturing (Mould SDM) and the gelcasting process to fabricate monolithic ceramic heat exchangers. This approach not only makes one-piece heat exchangers possible but introduces materials with superior thermal properties to the heat management applications. Silicon carbide is chosen for such applications because of its high thermal conductivity, thermal resistance, and corrosion resistance. The high chemical resistance of ceramic materials also extends the use of heat exchangers to chemical processing devices such as chemical reactors. The initial investigation of the process for micro reactors is also discussed.

Micro-Scale Radial-Flow Compressor Impeller Made of Silicon Nitride: Manufacturing and Performance

A micro-scale, high-speed compressor impeller (12mm diameter, 800,000rpm) was tested for feasibility in regard to aerodynamic performance. The compressor was designed for application in a fist-sized gas-turbine-generator. To survive high stresses at such high temperatures, the rotor was manufactured as a single turbine/compressor/shaft unit in silicon nitride, by the Mold SDM process. Performance testing was conducted in a cold-flow rig at reduced speed of 420,000rpm. Results from a CFD code compared favorably to measured data at this speed. Extrapolation from test conditions to full design speed was accomplished by application of CFD applied at both speeds.