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.
Slip cast nitride-bonded silicon carbide bodies
The dispersion behaviour of SiC, Si and their mixtures, in deionised water, was studied as a function of pH by sedimentation, viscosity, rheology and zeta potential measurements. Slips of SiC + Si mixtures (3:1, 1:1 and 1:3 weight ratios) with 1 wt.% of Fe2O3 (with respect to Si), conditioned in the pH range 8-9.5 were slip cast to 56-65% dense green bodies. These on nitridation under 0.18 MPa pressure of high-purity nitrogen at 1400-1450 xB0;C for 2-4 h resulted in nitride-bonded SiC bodies having 30-76 vol.% of Si3N4 bond, densities of 2.1-2.4 g cm-3 and 3-point flexural strengths of 60-220 MPa. The phase analyses of the products were carried out by XRD and microstructure by SEM studies. xA9; 2002 Published by Elsevier Science B.V.
Shape and surface texture of molten droplets deposited on cold surfaces
When a molten droplet impacts on a cold surface, the interaction between solidification and fluid dynamics can lead to different shapes and surface textures of deposited droplets. This article presents an experimental study on deposition of small droplets (39 μm diameter) of molten wax ink on solid surfaces. Our results show that both the final shape and the surface texture of deposited droplets are extremely sensitive to deposition conditions, which include initial temperature of droplets, type of substrate surface and distance between substrate and printhead. Different surface textures are observed and shown to depend on the thermal and flow histories of ink droplets during the process of impact. A test using crystalline wax reveals crystallization as one of the major factors in determining the final texture.