Si(Zr)BCN Ceramics from the Pyrolsysis of Zirconium-Modified Poly(boro)silazanes

 

            Zirconium-modified polysilazanes can withstand high temperatures, making them suitable for

applications in harsh environments.  These materials exhibit high strength and toughness, especially

when used in composite form.  They can be used to create a wide range of ceramic materials with tailored properties.  Si(Zr)CN nanocomposites, derived from these precursors, are used in turbine engines due to their excellent mechanical properties and high oxidation and corrosion tolerance. Zirconium-modified polysilazanes are used to create ceramic matrix composites (CMCs) for applications like rocket nozzles, nose tips, and leading edges of reusable launch vehicles.

            These materials can be used as high-heat resistant resins in fiber-reinforced composites for thermal

protection systems. Compared to SiBCN, the SiBCNZr composites exhibit reliable thermal stability

and ablation resistance in a wide temperature range. A dense oxide layer dominated by ZrO2 and SiO2

formed in situ on the surface of SiBCNZr, effectively preventing outside oxygen and further ablation.

In Si(Zr)CN ceramics the Zr is  evenly distributed, which enables outstanding ablation resistance at high oxygen acetylene torch temperatures.  Compared to SiBCN, Si(Zr)BCN composites also exhibit reliable thermal stability and ablation resistance in a wide temperature range. A dense oxide layer dominated by ZrO2 and SiO2 formed in situ on the surface of Si(Zr)BCN, effectively prevents outside oxygen from permeating the ceraming and prevents further ablation. The introduced Zr is evenly distributed in SiBCN ceramics.