Dynamic convection-driven thermal gradient chemical vapor infiltration
Dynamic convection-driven thermal gradient chemical vapor infiltration
复制标题
动态对流驱动的热梯度化学气相渗透
DOI：
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
S. V. Sotirchos
中科院分区：
文献类型：
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作者：
J. Ofori;S. V. Sotirchos
本文从理论上研究了压力脉冲和热梯度相结合的化学气相渗透工艺。过去的研究已经表明，气相中的压力的脉动可以导致致密化结构中的密度梯度的急剧减小，与等压扩散驱动的细滤中所见的密度梯度相比，仅在预成型件的外表面附近存在显著的梯度。使用一个详细的模型，化学气相渗透在不稳定的非等温条件下，我们表明，温度梯度，在我们的研究中，通过微波加热，可以结合压力脉冲，消除密度梯度在最终产品。此外，操作参数的适当调整可导致致密化从预成型件的内部朝向外表面进行的情况。
The operation of the process of chemical vapor infiltration using a combination of pressure pulsing and thermal gradients is theoretically investigated in this study. Past studies had shown that pulsing of the pressure in the gas phase can lead to a dramatic reduction of the density gradients in the densifying structure, in comparison to those seen in isobaric diffusion-driven Pinfiltration, with significant gradients present only in the vicinity of the external surface of the preforms. Using a detailed model for chemical vapor infiltration under unsteady nonisothermal conditions, we show that temperature gradients, created in our study through microwave heating, can, in conjunction with pressure pulsing, eliminate the density gradients in the final product. Moreover, appropriate tuning of the operational parameters can lead to a situation where densification proceeds from the interior of the preform toward the external surface.