Tuesday, 12 October 2004 - 3:55 PM

This presentation is part of : Damage and Composites II

Property Tailoring of Advanced Composites Nano Reinforcement to Porous Material Forms

Ajit K. Roy, Air Force Research Laboratory, Air Force Research Laboratory, AFRL/MLBCM, 2941 Hobson Way, Wright-Patterson AFB, OH 45433

Continuous carbon fiber (6 20 μm in diameter) reinforced advanced composites have proven structural materials in numerous applications for over three decades. The future of advance composites applications, however, can no longer afford to be limited to just one function. The other functionalities, such as thermal, electrical, magnetic, etc., the suite of multifunctional material attributes, along with enhanced structural performance are expected in the next generation of advanced composites in numerous systems.

Although advanced composites have offered many advantageous materials attributes over metallic materials, the materials discontinuity at the micron scale (the fiber matrix interface, in particular, causing stress concentration) of composites limits strength of the material. For example, origin of the process induced residual stresses, interlaminar stresses at the lamina interfaces, etc., that limit composite strength, is essentially due to the existence of the stress concentration of the fiber matrix interface. The enormous surface area to volume ratio of nano size inclusions in composites offers a renewed opportunity of tailoring properties of composites to enhance performance, as well as adding functionality to its performance. One of the key issues to making this achievable is to properly understand the adhesion and energy transfer characteristics of the nano inclusions in composites, requiring development of proper processing scheme, characterization methodology at appropriate scale levels and modeling tools. Our current work on nano scale characterization to understand the interface/interphase characteristics of the nano inclusions, processing efforts for exfoliation/intercalation of nano silicates, surface functionalization of the nano constituents, along with modeling to assess size and orientation of nano inclusions in tailoring composite properties will be discussed.

Porous carbonous material (commonly known as carbon foam) provides opportunities of material property tailoring for thermal management. The ligament microstructure of carbon foam with suitable processing is controlled to adjust mechanical properties as well as thermal conductivity. The ligament of carbon foam of open porosity can be coated, pores can be partially or completely infiltrated to meet certain material characteristics as needed.


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