Investigation of microstructure and properties in short carbon fiber reinforced silica-based ceramic cores via atmosphere sintering

Short carbon fiber (C-sf ) reinforced silica-based ceramic cores for investment casting were prepared by an injection molding approach and sintered in air and N2 atmospheres, respectively. SEM and XRD results present that there are some in-situ formed silicon carbides (SiC) in sintered samples. Moreover, as for the ceramic cores sintered in N-2 atmosphere, the peaks in XRD patterns related to the cristobalite increase with an increment in C-sf content, which may be attributed to the adhesion interface provided by the C-sf and the decreased crystallization free energy. Interestingly, the sample sintered in N-2 exhibits a higher flexural strength about 16.2 MPa, which is 155 % times than that of the samples sintered in air. This is originated from an obvious composite coating consisting of fused silica, SiC and cristobalite on the C-sf . In addition, the sintering necks can further enhance the interfacial bonding strength between the fibers and ceramic cores matrix.

Automated summary

Short carbon fiber (C-sf ) reinforced silica-based ceramic cores were prepared by injection molding and sintered in air and N2 atmospheres. The samples sintered in N-2 showed in-situ formed silicon carbides and increased cristobalite peaks in XRD patterns with higher flexural strength. The composite coating on the C-sf and enhanced interfacial bonding strength contribute to the improved mechanical properties of the ceramic cores.