Reaction mechanism and microstructure development of ZrSi 2 melt-infiltrated C f /SiC-ZrC-ZrB 2 composites: The influence of preform pore structures

Abstract Reactive melt infiltration (RMI) is an effective method for fabrication of highly dense carbon fiber reinforced ultra-high temperature ceramic matrix composites (C f /UHTCs). In this work, C f /SiC-ZrC-ZrB 2 composites were fabricated by infiltrating ZrSi 2 melt into porous C f /B 4 C-C preforms, where the physical and chemical reactions involved during the RMI process were identified and analyzed. Inhomogeneous infiltration between the inter- and intra-bundle pores was revealed, and was found to be strongly related to the pore structures of the C f /B 4 C-C preform. It is indicated that the inhomogeneous infiltration can be mitigated remarkably with increasing porosity and pore size of the preform. The effect of pore size on the RMI process was also investigated by a quantitative model, which agrees very well with the experiment results. It further indicates that the inhomogeneous infiltration can also be relieved at elevated RMI temperature. However, excessive infiltration at elevated temperature or more porous preform may cause serious erosion on interphase and fibers, leading to mechanical properties deterioration of the final composites.