Liquid immersion CVI

According to the controlling parameters used in the process, CVI approaches can be classified into five typical categories [9] isothermal/isobaric CVI (I-CVI), forced-flow CVI (F-CVI), thermal gradient/isobaric CVI (TG-CVI), pulsed CVI (P-CVI) and liquid immersion CVI (LI-CVI). There are more than ten CVI techniques if a particular method is coupled with plasma, microwave or a catalyst to enhance the process [10], Some representative techniques are discussed in this chapter as follows. 

The discussion in Section 5.4 clearly indicates that a temperature gradient has a significant influence on the densification of the preform. In order to increase the densification rate and improve the density, it is necessary to establish a very steep thermal gradient within the preform. In 1984 Houdayer el al. [52] described a method for rapid densification by immersing the preform into a liquid precursor at high temperatures to fabricate the C/C composites. This densification process is also called liquid-immersion CVI (LI-CVI). 

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