Structure/oxidation behavior relationship in the carbonaceous constituents of 2D-C/PyC/SiC composites
Structure/oxidation behavior relationship in the carbonaceous constituents of 2D-C/PyC/SiC composites
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DOI：
10.1016/0008-6223(93)90086-p
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发表时间：
1993
期刊：
影响因子：
10.9
通讯作者：
F. Lamouroux;X. Bourrat;R. Nasalain;J. Sévely
中科院分区：
文献类型：
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作者：
F. Lamouroux;X. Bourrat;R. Nasalain;J. Sévely
对 1.(a) 收到的 T300 纤维、2.(b) PyC 渗透丝束 3.(c) C/PyC/SiC 复合材料进行了氧化测试（在 500 <T< 900°C 下）。目的是评估复合材料中哪种碳质成分与氧的反应性最高。 TGA 和 TEM 用于建立材料在氧气中的行为与其纳米/微米纹理之间的关系。在加工状态下，纤维的总体氧化速率高于 PyC 中间相的氧化速率，而两种成分在 1600°C 退火处理后表现相似。超过 700°C，未涂层纤维氧化的决定速率步骤是外部停滞边界层中的扩散传输。在700°C以下，原态纤维是孔内扩散/表面反应混合模式，退火纤维主要是表面反应。纤维的氧化是选择性的。在横截面中，由于该特定区域的高孔隙率，它在外部区域发生得更快。 PyC 界面附近高孔隙率区域的出现对于理解环境对复合材料机械行为的影响起着关键作用。
Oxidation tests were performed (at 500 <T< 900°C), on1.(a) as-received T300 fiber,2.(b) PyC-infiltrated tows3.(c) C/PyC/SiC composite. The goal was to assess which carbonaceous constituent exhibits the highest reactivity with oxygen in the composites. TGA and TEM were used to establish the relationship between the behaviour of the materials in oxygen and their nano/microtexture. In the as-processed state, the overall oxidation rate of the fiber is higher than that of the PyC interphase, whereas both constituents behave in a similar way after an annealing treatment at 1600°C. Beyond 700°C, the rate-determining step in the oxidation of uncoated fibers is diffusion transport in the external stagnant boundary layer. Below 700°C, it is a mixed in-pore diffusion/surface reaction mode for the as-received fibers and mainly surface reaction for the annealed fibers. The oxidation of the fiber is selective. In cross-section, it occurs more rapidly in the outer zone, owing to the high porosity of this specific zone. The occurrence of a high porosity zone very near the PyC interphase plays a key role in understanding the effect of environment on the mechanical behaviour of the composites.