Pressure-pulsed-CVI

Naslain R, Pailler R, Bourrat X, Bertrand S, Heurtevent F, Dupel P, Lamouroux F (2001) Synthesis of highly tailored ceramic matrix composites by pressure-pulsed CVI. Solid State Ion 141-142 541-548... 

Naslain R Pailler R., Bourrat X., Bertrand S., Heurlevent F., Dupel P. and Lcmouroux F. Synthesis of Highly Tailored Ceramic Matrix Composites by Pressure-pulsed CVI // Solid State Ion. 2001. V. 141. P. 541-548. 

Finally, pressure-pulsed-CVI (P-CVI) has recently been presented as a means of engineering, at the micrometer (or even nanometer) scale, either the interphase or the matrix. Based on this technique, multilayered selfhealing interphases and matrices (combining crack-arrester layers and glass-former layers) have been designed and produced, through a proper selection of chemical composition of the layers [539]. 

The P-CVI processing parameters include the deposition temperature and pressure, precursor injection time, holding time, evacuation time and the number of pulses. 

In order to overcome the above limitations of the F-CVI technique, alternative techniques using thermal gradients or pressure gradients have been examined for several years [11]. In the thermal gradient process, the core of the fibrous preform is heated in a cold wall reactor. The heat loss by radiation is favorable to get a colder temperature in the external surface. The densification front advances progressively from the internal hot zone toward the cold side of the preform. In the P-CVI process, the source gases are introduced during short pulses [11]. The P-CVI process is appropriate to the deposition of thin films. 

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