Layer by layer E-beam curing of filament wound composite materials with low energy electron beam accelerators

摘要

In recent years both in Europe and in USA the most important aerospace companies have significantly increased their interests on new curing processes, based on the electron irradiation, for the manufacturing of composite materials. The reason ofthese interests can be found in the potential advantages associated to the electron beam curing, both in terms of cost-effectiveness of the manufacturing process and of "added value" in the obtained products.Currently the electron beam curing associated to the filament winding manufacturing process has been applied to polymerise the composite after the completion of the winding process, i.e. after the structure wound around the mandrel has reached its finalthickness. In the frame of this approach the polymerisation of the product throughout all its thickness can be only achieved using high energy electrons (> 5 MeV) or, in the case the thickness to be penetrated is significant (some cm), X-rays generated by the interaction of an energetic electron beam (in the range of 10 MeV) with a target made of material with a high atomic number (ref. AEROSPATIALE process).Proel Tecnologie, now a Division of LABEN SpA (a Finmeccanica Company) has proposed a totally new method for the electron beam curing of filament wound composites. This method uses a low energy (≤ 500 KeV) electron beam to achieve the curing of theproduct during the phase of deposition, around the mandrel, of the resin impregnated fibers. In this way the composite is polymerised and grown layer-after-layer, the desired thickness is achieved. As the thickness of a single (or eventually few) layer/spenetrated by the electron beam is of the order of some hundreds microns, the corresponding electron energy can be in the range of some hundreds KeV.In the framework of the research and development activities carried out by LABEN Proel Tecnologie Division (hereinafter Proel Tecnologie) on this new process (patented), called "layer-by-layer E-beam curing", new proprietary resin formulations, suitablefor the cationic polymerisation mechanism, and composite sample have been prepared and characterised.In the paper both the technical aspects relevant to the layer-by-layer polymerisation process with proprietary formulations and the cost effectiveness advantages intrinsically associated to the new process are addressed and are discussed in detail.