Influence of oxidation inhibitor on carbon-carbon composites: 4. Gibbs surface free energy and ILSS improvement

The effects of molybdenum disilicide (MoSi₂) on the surface free energy of unidirectional carbon-carbon composites were investigated by contact angle measurements at room temperature. The contact angle measurements were carried out employing a Rame-Hart contact angle goniometer. Deionized water, diiodomethane and ethylene glycol were chosen as the testing liquids. In this work, Owens-Wendt and Wu's models were studied to analyze the surface free energy of the composites. As a result, the composites made with MoSi₂ showed an increase of the London dispersive component of the surface free energy. But, the specific or polar component was not influenced by the addition of MoSi₂. Interlaminar shear strength of the composites determined by short-beam tests increased with increasing the MoSi₂ contents. As mentioned above, this is due to improving the London dispersive component of surface free energy of the composites.