Coking characteristics of low density ablators

实验研究了低密度碳酚醛烧蚀材料在空气动力加热下的结焦现象。测量了在电弧风洞中加热的材料的深度密度和透气性。向炭层表面方向，密度增大，透气性减小。造成这种趋势的原因很可能是由于焦化效应：焦炭层的焦化是一种被称为焦化的现象，即当热解气体穿过多孔的焦炭层到达表面时，在CH4等碳氢化合物的化学分解反应下，在焦炭层内沉积固体碳。本研究发现，在低密度碳酚醛烧蚀器中可能发生焦化。

Coking phenomenon in low density carbon phenolic ablative material exposed to aerodynamic heating is examined experimentally. The in-depth density and gas permeability of the material heated in an arcjet wind tunnel is measured. Toward the surface within the char layer, the density increases and the gas permeability decreases respectively. The reason for such a trend is likely due to coking effect: coking in the char layer is known as a phenomenon that when the pyrolysis gas passes through the porous char layer to the surface, solid carbon is deposited within the char layer under the chemical decomposition reaction of hydrocarbon species such as CH4.It is find in this study that coking could occur in a low density carbon-phenolic ablator.