Papers by Keyword: Preforms

Abstract: The carbon fiber mat preforms are prepared by an air laid method with different fiber lengths of 10mm, 30mm and 50mm to characterize the resultant discontinuous composites. The composites are manufactured by a vacuum assisted resin infusion (VaRI) molding technique with the use of epoxy resins to investigate the effects of carbon fiber length on their physical and mechanical properties. The void content and thickness of the composites decrease with the increase in the fiber length at the same VaRI processing conditions. The tensile, flexural, impact properties of the composites are improved by increasing the fiber length in the textile preforms. By comparing with those of carbon fiber fabric reinforced composites, the discontinuous composites demonstrate the excellent performance in strength and modulus in spite of lower fiber volume fraction.

Abstract: The Poly-crystal alumina short fiber reinforcing 2024 matrix composites was produced by the gas pressure infiltration, and a new apparatus has been developed for the infiltration of MMCs by the gas pressure infiltration technique. The reasonable sintering parameter for the preform were determined.The preform was heated at 450°C to remove the organic binder and pore-forming material, and then heated at 1050°C for 2.5h to obtain the comprehensive properties.Scanning electron microscope was used to observe the tensile fracture of Aluminum matrix composites, and the fracture feature of composites produced in different temperature was analyzed. The melting temperature of 2024Al was 800°C and holding time was 20mins; the infiltration gas pressure was 0.5Mpa and holding time was 20s.And then interface reaction is appropriate between the fiber and matrix ,a good performance of composites was produced.

Abstract: Processes of the Liquid Composite Molding (LCM) are widely used in composites produced by impregnation of a dry preform with liquid resin. The resin flow through the preform is usually described by Darcy’s law and the permeability tensor must be obtained for filling process analysis and characterizing the ability of a porous material to be impregnated by a resin fluid. In generally, resin flow in the thickness direction can be neglected for thin parts, but the resin flow in the transverse direction is important for thicker parts. In this study, the transverse permeability measurement device using ultrasound method was developed, the transverse flowfront could be calculated, and global effective permeability and transverse were studied.