Processing and characterization of paper-derived Ti₃SiC₂ based ceramic

Porous layers of paper-derived titanium silicon carbide (Ti₃SiC₂), with a thickness ranging from 300 to 700 μm, were obtained by the heat treatment of preceramic papers containing Ti₃SiC₂ as filler particles. The tearing strength of the preceramic papers was provided by cellulose fibers obtained from wood by the kraft pulping process, also described as pulp fibers, and ionic starches. Short pulp fibers with an average length of 657 μm were derived from short fibered hardwood (eucalyptus), while long pulp fibers with an average length of 1665 μm were derived from long fibered softwood (spruce, pine and larch). The fiber length of pulp fibers in the preceramic papers also influenced the microstructure and the properties of the paper-derived Ti₃SiC₂. Preceramic papers fabricated with short pulp fibers exclusively led to an average porosity of 18.6 vol% for the paper-derived Ti₃SiC₂, whereas the paper-derived Ti₃SiC₂ had an average porosity of 45.3 vol% when preceramic papers with long pulp fibers only were used. The density of the paper-derived Ti₃SiC₂ also affected the flexural strength, as could be shown by densifying preceramic papers using a calender. Thereby, the flexural strength of paper-derived Ti₃SiC₂ could be increased by more than five times, from 13 MPa to 83 MPa. The purity of the paper-derived Ti₃SiC₂ was found to be dependent on the purity of the raw materials and the process cycle, with TiC_x and Al₂O₃ impurities present in the ceramics.