Microstructural Control Carbon Materials by Addition of Inorganic Compounds into a Precursor and Chemical/Mechanical Properties Improvement

在碳前驱体中加入碳质颗粒可以控制碳材料的微观结构。碳材料的氧化失重与其微观结构有关，氧化过程在材料内部不均匀进行。不均匀的氧化可以通过维克的压痕技术来检测：利用压痕深度中加载和卸载曲线之间的区域来确定加载关系。这一区域对应于材料中消耗的能量，该能量随最大压痕载荷而变化，然而，由最大压痕体积修正的能量表现出无载荷相关性，并清楚地解释了氧化面积的增加和压痕断裂抗力的降低。显然，该技术可以非常精确地分析碳材料氧化中常见的不均匀氧化行为，包括无机化合物在内的碳材料的氧化速率在700-1000之间。空气中的C取决于化合物。用TK(瞬时动力学)对氧化行为的精确分析表明，碳材料中可能存在两种以上的活性中心，一些元素，在这种情况下，Ta和Ti，可以使一种类型的活性中心失活。利用该基料可以制备C/C复合材料，且剪切强度仅有较小的下降，表明本研究可以制备出抗氧化性高、强度下降较小的碳材料。此外，还提出了一种可以定量分析材料中不均匀氧化的技术。

Microstructure of carbon materials can be controlled by addition of carbonaceous particles into carbon precursors. Oxidation weight loss of the carbon materials depends on their microstructures, and the oxidation progresses un-uniformly in the materials. Un-uniform oxidation can be detected by Vicker's indentation technique : using the area surrounding between loading and unloading curves in indentation depth to load relationships. This area corresponds to the energy dissipated in materials, This energy is variable depending on the maximum indentation load, However, the energy corrected by the maximum indentated volume shows no-load dependence, and clearly explains increasing oxidation areas and decreasing resistance against indentation fracture. It is obvious that this technique can be applicable to analyze un-uniform oxidation behavior, which is usual in carbon material's oxidation, very precisely.Oxidation rate of carbon materials including inorganic compounds at 700 to 1000 。C in air depends on the compounds. Precise analysis of oxidation behavior using TK (Transient Kinetics) reveals that more than two types of active sites possibly exist in carbon materials and that some elements, in this case Ta and Ti, can disactive a type of active sites. C/C composites can be prepared by using this type of matrix, and only small decreasing in shear strength is observed.Above results indicate that carbon materials having high oxidation resistance and low strength decreasing can be prepared in this study. Moreover, a technique, by which un-uniform oxidation in a material can be quantitatively analyzed, is proposed.