Composite matrix with steel reinforcement

All VGCF was graphitized prior to composite consolidation. Composites were molded in steel molds lined with fiberglass reinforced, non-porous Teflon release sheets. The finished composite panels were trimmed of resin flash and weighed to determine the fiber fraction. Thermal conductivity and thermal expansion measurements of the various polymer matrix composites are given in Table 6. Table 7 gives results from mechanical property measurements. 

Subclass B2 is formed by the so-called structural composites, in which an outspoken mechanical reinforcement is given to the polymer. Subgroup B21 consists of blends of polymers with compatible anti-plasticizers subgroups B22 are the most important the fibre-reinforced polymer systems. The two components, the polymer matrix and the reinforcing fibbers or filaments (glass, ceramic, steel, textile, etc.) perform different functions the fibrous material carries the load, while the matrix distributes the load the fibbers act as crack stoppers, the matrix as impact-energy absorber and reinforcement connector. Interfacial bonding is the crucial problem. 

If concrete removal is not required or supplementary reinforcing bars cannot be used, external reinforcement can be applied. For instance, steel bars may be encased in a shotcrete layer or steel plates may be bonded onto the concrete surface. Recently, the use of steel plates has been substituted by fibre-reinforced plastics (F. R.P.), that are composite materials with glass, aramide or carbon fibres embedded in a polymeric matrix (usually an epoxy system). F. R.P. are available in the form of laminates or sheets that are bonded to the concrete surface using an epoxy adhesive [11]. They are typically used to improve the flexural and shear strength or to provide confinement to concrete subjected to compression. The... 

Polymer matrix composites (PMCs), or fiber-reinforced plastics (FRPs). provide a wide range of properties and behavior. Materials with discontinuous fibers are slightly stiffer than conventional unreinforced plastics, whereas the fully aligned continuous fiber systems can record exceptionally high specific properties (property divided by density), exeeeding those of competing materials such as steel and aluminum. There are a virtually infinite number of materials, and material formats that can be combined to form a composite material, as shown in Table 1. 

As reviewed a composite is a combination of two or more materials with properties that the components do not have by themselves. They are made to behave as a single material. Nature made the first composite in living things. Wood is a composite of cellulose fibers held together with a matrix of lignin. Most sedimentary rocks are composites of particles bonded together by natural cement and many metallic alloys are composites of several quite different constituents. On a macro scale, these are all homogeneous materials. There are steel reinforced concrete, medical pills, and more. Included is RPs. 

In an earlier study, Ducheyne and Hench fabricated composite materials with a bioactive glass (Bioglass ) matrix and stainless steel fibre reinforcement by an immersion technique [25]. Donald et al. have reported on the fabrication of glass and glass-ceramic matrix composites reinforced by stainless steel and Ni-based alloy filaments with diameters in the range 4 to 22 [jum [100, 101]. Glass-encapsulated metal filaments prepared by the Taylor-wire process were used for the fabrication of the composites [100]. 

Composites can occur naturally or may be synthetically produced. For example, wood is a naturally occurring, water-plasticized composite consisting of oriented cellulose fibers in a continuous, cross-linked matrix of lignin. With synthetically produced composites, the matrix may, for example, be a metal (an example of which is steel-reinforced concrete). Here, the discussion will be limited to composites with synthetic polymers as the matrix material. 

Fiber-reinforced plastics are the most successful composite materials. In spite of the poor load-bearing ability of polymeric materials, excellent mechanical properties are achieved by using fiber architectures of glass and carbon hbers in a manner similar to the reinforcement of concrete with steel rods and frames. For example, toughened polymeric materials with dispersed rubber particles in a polymer matrix exhibit high fracture energy. In composite materials, introduction of secondary materials into the matrix can improve the mechanical properties considerably. 

A special type of this material is called SIFCA slurry infiltrated fiber-reinforced castable. This is a composite material of ceramic matrix with calcium aluminate cement and with aggregate made of aluminum oxide, mullite, zircon and calcined fireclay. The matrix is reinforced with stainless-steel fibres. SIFCA is used to made pre-cast elements for refractory structures, where temperature can rise up to 1100°C. Heat curing is often used during the pre-casting. Another kind of similar material is called SIMCON slurry infiltrated mat concrete in which arrays of single fibres are replaced by a system of steel mats for better and easier distribution of reinforcement (Murakami and Zeng 1998). 

Tjiptobroto and Hansen [12] investigated these composites with steel fibre reinforcement of 0.15 mmdiameter andGmm length, at contents in the range of 3-6% by volume. The flexural behaviour demonstrated high ductility, with a considerable strain hardening effect as shown in Figure 12.13. The strain capacity of the matrix was 150 microstrain and it increased to 2000 microstrain in the 12% fibre composite. 

FIGURE 13.12 Composite coefficient of friction for polyester-based matrix material. Symbol legend Glass fiber-reinforced polymer O-parallel, A-antiparallel, Steel-reinforced polymer -parallel, A-antiparallel, H-normal, carbon fiber-reinforced polymer -parallel, A-antiparallel, B-normal. (Reprinted from Friction and Wear of Polymer Composites, Composite Materials Series, Friedrich, K., ed., 1, T. Tsnkizoe and N. Ohmae, pp. 212-220, Elsevier, New York, 1986, with permission from Elsevier.)... 

The descriptions presented in the foregoing sections are concerned mainly with composites containing brittle fibers and brittle matrices. If the composite contains ductile fibers or matrix material, the work of plastic deformation of the composite constituents must also be taken into account in the total fracture toughness equation. If a composite contains a brittle matrix reinforced with ductile libers, such as steel wire-cement matrix systems, the fracture toughness of the composite is derived significantly from the work done in plastically shearing the fiber as it is extracted from the cracked matrix. The work done due to the plastic flow of fiber over a distance on either side of the matrix fracture plane, which is of the order of the fiber diameter d, is given by (Tetelman, 1969)... 

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