Reactive mechanisms of pyrolysis of stereolithography prototype for preparation of carbon template

A novel process for fabricating complex-shaped silicon carbide ceramic parts based on the stereolithography (SL) prototyping technology is presented. Carbon template is fabricated by pyrolysis of SL prototype at a heating rate of 20°C/min from room temperature to 800°C and then hold 30 min under vacuum. The identification of volatile components derived from pyrolysis of photo-curable resin is investigated by pyrolysis/Fourier transforms infrared spectrometer (Py/FTIR). The elements identification and chemical bond analysis of the pyrolyzate of photo-curable resin are studied by X-ray photoelectron spectrometer (XPS) and FTIR respectively. The morphology of the carbon template is analyzed by scanning electron microscope (SEM). Open porosity of the carbon templates are measured by Archimedes principle. The results show that the pyrolysis reaction is a condensation polymerization process in which low molecular weight paraffin hydrocarbon, CO₂ and aldehyde are produced and escape in gaseity. So a little carbon is lost. The pyrolyzates are porous carbonaceous materials that contain a little H and O. The open porosity is 42% and increases with the heating rate. The residual carbon mass fraction of SL prototype is 10%. The bending strength of the carbon template is 22 MPa that is sufficient for the requirement of infiltration of Si.