Fabrication of Polymer-Derived Silicon Oxycarbide Microparts and Their Mechanical Characteristics

Abstract

In this paper, fabrication and mechanical characterization of silicon oxycarbide (SiOC) microparts made from polycarbosilane (PCS) precursor is described. The developed fabrication technique is a combination of ultraviolet thick photoresist lithography and slip casting. The slips consisting of β-SiC nanoparticles and a PCS solution are cast into SU-8 photoresist micromold, fabricated on a porous tungsten carbide plate. The plate works as a filter for solid–liquid separation. The cast slips are fired at 1000 °C in N2 gas flow for an hour. During the firing, the SiOC body can be released from the mold because of SU-8 vaporization at 450 °C. By using the technique, we have successfully produced SiOC microgears with diameters ranging from 0.5 mm to 2 mm. To improve the mechanical reliability, the polymer infiltration and pyrolysis (PIP) process is carried out. The influence of the PIP process is evaluated by means of the nanoindentation test. The Young's modulus and hardness are increased with increasing PIP process cycles. From energy dispersive X-ray measurement results, it is found that their distributions are related to the amount of oxygen and the carbon-to-silicon ratio.