Silicon Carbide Micro-reaction-sintering using a multilayer silicon mold

This paper describes a novel process, `Silicon Carbide Micro-reaction-sintering', to fabricate high-aspect-ratio silicon carbide microstructures. This process consists of micromachining of silicon molds, filling of material powders (α-silicon carbide, graphite, silicon and phenol resin) into the molds, bonding of the molds with adhesive and reaction-sintering by hot isostatic pressing (HIP). Using our process, we have successfully fabricated silicon carbide microrotors of 5 and 10 mm diameters for micromachined gas turbines. We observed the cross section of the microrotors with a scanning electron microscope (SEM). The SEM observation demonstrated that the material powder was densely reaction-sintered by HIP. We also investigated the compositions of the microrotors by X-ray diffraction (XRD) analysis. The XRD analyses proved that graphite in the material powder reacted with melted silicon derived from the mold, and consequently β-silicon carbide was produced around the α-silicon carbide originally included in the material powder.