表面涂层对碳纤维的强度和断裂特征的影响

利用化学气相沉积法在碳纤维表面获得了ＳｉＣ，Ｃ＋ＳｉＣ，Ｓｉ，Ｃ－Ｓｉ梯度等多种涂层，研究了各种涂层对碳纤维强度的影响，分析了涂层碳纤维的断裂过程与断口形貌，实验结果显示：Ｃ－Ｓｉ梯度涂层碳纤维具有较高的抗拉强度，这是任何单一涂层所无法比抉的。另外，单Ｓｉ涂层碳纤维的断口为拨出型，其它几种涂层碳纤维的断口为平切型。

On Effect of Surface Coating on Strength and Fracture of Carbon Fiber

In this paper,the author presents the result of his endeavor to improve the mechanical properties ofcomposites.There exists now the following cause for poor mechanical properties:small surface area of ac-tivity of carbon fiber (CF) makes its surface liquid-repellent and thus leads to poor wetting property be-tween CF and metal matrix.Employing CVD (chemical vapor deposition) method,the author obtainsuniform SiC coating,C+SiC composite coating,Si coating and C-Si gradient coating on the surface ofCF.Experiments show that,of the four coatings,C-Si gradient coating has the least internal stresses(infact approaching zero),C-Si gradient coating makes CF with coating possess the highest tensile strength,and makes CF with coating possess the highest wetting property when in contact with metal matrix.Infact these beneficial effects of C-Si gradient coating are better than those of any previously knowncoating.The author also finds that the appearance of fracture of CF with C-Si gradient coating is offlat-cutting type and its failure mechanism is transgranular propagation of cracks in carbon fiber.The au-thor deems that such fracture phenomena are in good agreement with the good mechanical properties ofCF with C-Si gradient coating.