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.
Synthesis of continuous silicon carbide fibre
Polycarbosilanes which are the precursors of SiC fibre were synthesized by three methods. The molecular structure of each polycarbosilane was represented by means of three structural elements determined by IR, UV and NMR spectral measurements. The pyrolysis process of the polycarbosilanes is discussed for the six stages observed in the TG-DTA curves and gas evolution curves during pyrolysis of the polycarbosilanes. In each stage, the relationship between the molecular structure and the structure of the pyrolysis product is discussed and the pyrolysis process of the polycarbosilanes is characterized.
Thermal stability of SiC fibres (Nicalon®)
The degradation behaviour of Nippon Carbon Co. SiC fibres (Nicalon®) after heat treatment in various environments was studied. Regardless of the heat-treatment conditions, the Nicalon® fibre strength degraded when the fibres were subjected to temperatures higher than 1200° C (temperatures below 1200° C were not investigated). This degradation is associated with the evaporation of CO from the fibres as well as withβ-SiC grain growth in the fibres.