Preparación y caracterización de materiales de oxicarburo de silicio mixtos

In this work different mixed Silicon oxicarbide materials have been prepared. Si, Si-Ti, Si-Zr and Si-Al oxicarbide materials have been obtained from pyrolisis at 1000 °C and 1300 °C of the respective preceramic materials. After pyrolisis X, D and T units of the oxycarbide structure have been observed in such materials. They show the presence of Si-C and Si-O bonds in a given material. The characterization has been carried out by means of FT-IR, Raman NMR ²⁹Si, NMR ¹³C and XRD. The formation of Si-Ti, Si-Zr and Si-Al bonds has been estimated in accordance with the decrease of the Si-O-Si wave number observed in the FT-IR spectra. Si and Si-Ti oxycarbide materials do not lead to crystallisation after pyrolisis at highest temperatures, however for Si-Zr and Si-Al oxycarbide materials different crystalline phases have been observed. All pyrolised materials present free and carbidic carbon. After pyrolisis at 1300 °C the free carbon reacts with Si-O bonds to form SiC4 groups which must be assigned to nucleus of the β-SiC crystals.