Polycarbosilane-derived silicon carbide MEMS component fabricated by slip casting with SU8 micro mold
In this paper, we describe a new production method for microscale silicon carbide (SiC) ceramics parts. Slip casting with SU8 micro mold was carried out for the fabrication of a three-dimensional SiC MEMS component, which was made from polycarbosilane (PCS) precursor-derived SiC nano powder. SiC nano powder was mixed with a PCS solution. The slips were then cast into SU8 micro mold made on porous tungsten carbide (WC) plate. Firing at 1273 K was conducted for SU8 evaporation and PCS pyrolysis. We have succeeded in producing microscale SiC ceramics gears using the “μ slip casting” technique.
Fabrication of Micro-featured Shapes of Alumina Ceramics
Abstract The present paper discusses the investigation carried out on three casting methods employed for the fabrication of micro featured shapes of alumina ceramics. The study involves the colloidal processing of submicron sized alumina powder in deionised water as well as in a mixture of deionised water and monomer followed by various casting techniques namely slip casting, gel casting and mouldless casting. While the slip casting method uses porous moulds and gel casting uses non porous moulds, the novel mouldless casting method does not use any mould. The experimental tools used for optimization of the slurry for the different casting techniques and the results obtained are presented. The cast products were sintered in the temperature range of 1400 °C to 1600 °C and were characterized for density, porosity, microstructure development and mechanical properties. The viability of three methods for producing micro features in the range of 50 to 500 μm both on the surface as well as internally in the 3 dimensional structures have been demonstrated.
SiO2+SiC reaction at elevated temperatures. Part 1.—Kinetics and mechanism
The reaction between finely divided SiO2 and SiC at 1270–1430°C was studied. The reaction scheme proposed is: 2SiC+SiO2= 3Sia+2COa 2Sia+CO = SiOa+SiC Sia+SiO2= 2SiOa Sia, SiOa, COa= Sig, SiOg COg. During the first 2–6% of reaction, Si volatilizes; thereafter primarily SiO and CO volatilize. Only the upper layers of the charge contribute to the net forward reaction rate, hence the state of reactant subdivision is of secondary importance. An Arrhenius plot of the reaction in vacuo gives an apparent activation energy of 131–97 kcal/mole in the range 1270–1430°C. The rate-determining step is desorption of products from the SiC surface.