VACUUM INFUSION AND curing of
composites for high temperature applications
Amol Ogale1, David Leach2, Ehsan Barjasteh2, Helder Barros-Abreu3, Dale Brosius4, Jens Schlimbach1
1 Quickstep GmbH, Rolf-Engel-Strasse 6.5, 85521 Ottobrunn, Germany; 2 Henkel Aerospace, 2850 Willow Pass Road, Bay Point CA 94565; 3 Henkel AG, Henkelstrasse, Dusseldorf, Germany; 4 Quickstep Composites LLC, 3251 McCall St., Dayton, OH 45417
Fiber reinforced polymer composites are increasingly considered for replacing metals in high temperature-resistant components for aircraft or helicopters (service temperature >190 °C). There are very limited resin options available to manufacture such composite components. One system of considerable interest is the family of benzoxazine resins, which offer high glass transition temperatures and excellent hot/wet performance, combined with room temperature storage and easy processing. The main objective of this work was to develop an energy efficient and manufacturing friendly Out-of-Autoclave (OoA) manufacturing technique for a commercially available high temperature benzoxazine resin.
This paper presents the process development for the infusion of the benzoxazine resin into carbon fiber preforms, followed by subsequent cure and postcuring. Physical and thermal behavior, including mechanical performance after impact damage is reported. An integrally stiffened structure was produced as a demonstrator to evaluate the behavior of the benzoxazine resin in a complex infusion situation. The Quickstep OoA curing process was used to demonstrate highly efficient manufacture of the panels and demonstrator parts.
A Rapid Heating Process for Out-of-Autoclave Curing of Toughened Epoxy Prepregs.
Dale Brosius and Benjamin Luedtke, Quickstep Composites LLC Karl Gruenberg, Vector Composites, Inc. 3251 McCall Street Dayton, OH 45417
Toughened epoxy prepregs are utilized in advanced composite structures on military aircraft. The conventional processing route employs autoclave curing under a pressure of 7 bars (100 psi) and long cycle times to achieve final properties. An out-of-autoclave advanced composite curing technology has been employed that uses a heat transfer fluid (HTF) to apply heat and modest pressure to the uncured epoxy prepreg during processing. The HTF enables precise control of the process temperature throughout the curing process. As this technology is based on rapid heat transfer and the ability to accurately control mold temperature, it offers potential savings on process time, energy, investment, and overall component manufacturing costs. Additionally, a differential vacuum technique has been applied to the laminates during the cure cycle that yields void-free laminates. This paper reviews the progression of the process development and the resulting panel and component qualities. Data showing process parameters, laminate properties, and cured components are presented.
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