Composites alumina/polyimide

Yoldas B.E. Alumina sol preparation from alkoxides. Am. Ceram. Soc. Bull. 1975 54 289-290 Yoshida M., Lai M., Kumar N.D., Prasad P.N. Ti02 nano-particle-dispersed polyimide composite optical waveguide materials through reverse micelles. J. Mater. Sd. 1997 32 4047-4051 Yoshizawa K., Sugoh Y., Ochi Y. Controlled growth of monodispersed spherical silica by a new synthetic process. In Science ofCeramics Vol. 14, D. Taylor, ed. Stoke-on-Trent, UK The Institute of Ceramics, 1988... 

The common commercially available fibers used in composites are fiberglass, graphite (carbon), aramid, polyethylene, boron, silicon carbide, and other ceramics such as silicon nitride, alumina, and alumina silica. Many matrix choices are available, both thermosetting and thermoplastic. Each type has an impact on the processing technique, physical properties, and environmental resistance of the finished composite. The most common resin matrices include polyester, vinyl esters, epoxy, bismaleimides, polyimides, cyanate ester, and triazine. 

These preliminary results show that polyimide-alumina composites combine together some properties that are very useful in cryogenic technology In the specific case of the TORE II project, alumina does not give a sufficiently low value of thermal conductivity on the other hand, A2 alumina seems to be limited by mechanical considerations An intermediate powder quality could be the best compromise ... 

Until now, the macroscopic tribological properties of the nanotubes had not been studied. The only studies carried out used the nanotubes as reinforcement in various matrices diamond thin film [87], polyimide [88], Ni [89], Ni-P [90], carbon/carbon composites [91] and alumina [92, 93]. These composite coatings present a better wear resistance and a lower friction. In nanotribology, Ohmae et al. studied friction of a gold tip on a nanotube forest. The friction coefficient obtained was high (1.2 to 1.5) and independent of humidity [94]. A very weak adhesion of the tip on the nanotubes was observed. During friction, no distortion of the nanotubes intervenes and there is no transfer of nanotubes on the tip. Recently, Miyoshi et al. 

Compared with epoxy adhesives, polyimides share a very small part of the global market, limited to military, aerospace, and geothermal applications requiring long-term stability at elevated temperatures. Owing to their aromatic heterocyclic structure, virtually all polyimides are stable at 300 °C. When loaded with inorganic particles such as alumina, silica, silicon nitride, or aluminum, the thermal stability is still better. By contrast, some metals used in the composition of conductive adhesives, in particular silver and nickel, dramatically decrease the thermal resistance. This means that the adhesive strength of most polyimides is excellent at 200 °C,... 

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