Preparation of Biomorphic SiC-Ceramics by the Reactive Infiltraion of Si into Carbon Template Derived from Basswood

Abstract:

Basswood was transformed by high-temperature pyrolysis into carbon performs (charcoal) and subsequently converted into cellular SiC-ceramics possessing pseudomorphous microstructure by the reactive-infiltration of Si into CB-template in Ar atmos- phere.Thermogravimetric analysis (TGA) was applied to reveal the pyrolysis behavior of basswood powder.Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to characterize and analyze the microstructures and phase identification of CB-template and final SiC ceramics.The infiltration mechanism of liquid Si into charcoal and the basic properties of cellular SiC were also given.The results showed that CB-template was amorphous carbon materials.Final cellular SiC was composed of the major phase ?-SiC and a little unreacted carbon.Compared to charcoal,cellular SiC possessed higher mechanical properties.The improvement of the mechanical properties of materials was mainly caused by the following factors:one was the conversion of carbon fibres into SiC fibres,and the another was the volume expansion during CB-template-to-cellular SiC conversion,which inhibited the initiation and propagation of cracks and made cracks deflect.