Ultra-high temperature ceramic composites (UHTCMCs) have shown considerable potential for withstanding the extreme conditions found in a range of different applications in the space and military fields, such as rocket nozzle inserts and hypersonic leading edges. Different processes are being investigated to produce UHTCMCs, with sintering, chemical vapour infiltration (CVI) and polymer infiltration & pyrolysis (PIP) being the most common. The latter offers advantages in terms of relatively low processing temperatures (~1000°C) and the possibility of fine control of the matrix microstructure that can potentially overcome the relatively slow manufacturing time related to the several cycles required to obtain a satisfactory densification level. The introduction of transition metals in the preceramic polymer allows the formation of high melting point oxides that increase the stability of the resulting protective silica glass, which is otherwise easily removed due to the high gas flows that occur under typical thermo-ablation conditions.
 
In this work, the feasibility of using modified preceramic polymers to densify ceramic matrix composites for aerospace applications with ultra-high temperature properties at least comparable to those achieved by CVI-based UHTCMCs is being researched. A low-porosity green sample manufactured with woven carbon fibre and zirconium diboride powders is densified with a commercial polysilazane modified with a transition metal alkoxide and subsequently tested in subsonic ablation conditions at temperatures above 2000°C.