Modification of the physical properties of graphite fibers by fluorination with halogen fluorides
Modification of the physical properties of graphite fibers by fluorination with halogen fluorides
复制标题
卤素氟化物氟化对石墨纤维物理性能的改性
DOI：
10.1016/s0022-1139(00)83640-4
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发表时间：
1991
影响因子：
1.9
通讯作者：
D. Davidov
中科院分区：
文献类型：
--
作者：
H. Selig;M. Zayat;D. Davidov
石墨和碳纤维具有高拉伸强度，广泛用作复合材料中的增强剂。重要的是通过适当的处理来改变这种纤维的物理性能。纤维的电导率可以通过用插层剂如AsF 5插层它们而增加超过一个数量级。然而，在某些情况下，较低的电导率是期望的。这些是通过氟化纤维来实现的。具有高石墨化度的沥青基碳纤维已经用卤素氟化物IF 7、BrF 5或ClF 3处理，导致氟化纤维具有约C2FX 0.03 -0.06（X = Br或Cl）的最终化学计量。与ClF 3的反应为：ClF 3 + 4C → 2C 2F + ClF，其中忽略了少量的吸附氯。与IF 7的反应可以描述为：xC + yIF 7 → Cx（IF 5）F2 y+（y-1）IF 5;即，IF 5的一部分保留在晶格中。与BrF 5反应产生大量溴和一些BrF 3。也可以存在不稳定的BrF，后者与Br 2和BrF 3平衡。氟化纤维具有比原始纤维低几个数量级的电导率，这对于某些应用可能是有利的。它们的抗拉强度降低，但粘附程度显著增强，这将导致改善与基体的结合。
Graphite and carbon fibers possess high tensile strengths and are used extensively as reinforcing agents in composite materials. It is important to modify the physical properties of such fibers by appropriate treatment. The electrical conductivities of the fibers can be increased by over an order of magnitude by intercalating them with intercalating agents such as AsF5. However, in some cases lower conductivities are desirable. These are attained by fluorinating the fibers. Pitch based carbon fibers with high degree of graphitization have been treated with halogen fluorides IF7, BrF5or ClF3leading to fluorinated fibers having final stoichiometries of approximately C2FX0.03–0.06(X = Br or Cl). The reaction with ClF3is: ClF3+ 4C → 2C2F + ClF, where the small amounts of adsorbed chlorine are neglected. The reaction with IF7can be described as: xC + yIF7→ Cx(IF5)F2y+ (y−1)IF5; i.e., part of the IF5is retained in the lattice. The reaction with BrF5produces large amounts of bromine and some BrF3. The unstable BrF may also be present, the latter being in equilibrium with Br2and the BrF3.The fluorinated fibers have electrical conductivities several orders of magnitude lower than the pristine fibers, which may be advantageous for certain applications. Their tensile strengths are diminished, but the degree of adhesion is significantly enhanced by the fluorination treatment which should lead to improved bonding with the matrix.