- •Contents
- •Introduction
- •1 Prospects for the creation of silicate composite materials
- •1.1 History and development of composite materials, their properties and applications
- •1.2 Need for the development of new materials
- •1.3 Composite materials: matrix, interface, combination
- •1.4 Dispersion-strengthened composite materials
- •1.5 Composite materials
- •1.6 Eutectic composite materials
- •1.7 Effect of interphase boundaries on the strength of the silicate composite materials
- •1.8 Physical and chemical processes of interaction at the interface of silicate composite materials
- •1.9 Types of links on an interface of phases in silicate composite materials
- •2 Innovative aspects of combining portland cement with gypsum binder
- •2.1 Methods of sulfation of cement
- •2.2 Creation and gypsum cement gypsum composite materials
- •2.3 Hardening of gypsum cement compositions
- •2.4 Technological ways of controlling the conditions of formation of gypsum cement gypsum stone
- •2.5 Influence of pozzolanic additives
- •2.6 Role of amorphous silica
- •2.9 Role of fillers in the formation of stones
- •2.10 Technology of dry construction mixtures
- •3 Artificial composite materials – concretEs
- •3.1 Cement polymer concretes
- •3.2 Concrete with chemical additives
- •3.3 Concrete and mortar on liquid glass
- •3.4 The essential elements of mechanics and concrete technology
- •3.5 Structure formation and concrete structure
- •3.6 Description features of stress-strain state of concrete methods of solid mechanics
- •3.7 Elements of fracture mechanics of concrete
- •3.8 Over view of the phenomenological theories of concrete strength
- •3.9 Theory of deformation of concrete and the ratio of the physical relations between stresses and deformations
- •3.10 Theory of concrete creep
- •4 Composite-mineral binding substances on the basis of large-tonnage industrial waste
- •4.1 Classification and types of industrial wastes
- •4.2 Gypsum-containing by-products of production
- •4.3 Lime-containing industrial wastes
- •4.4 Aluminosilicate by-products of production
- •4.5 Siliceous waste industry
- •5 Composite ceramic materials
- •5.1 Nanocrystalline structure and adjustable porosity on the basis of kaolinite and montmorillonite clays
- •5.2 Ceramics based on oxides
- •5.3 Ceramics based on complex oxide compounds
- •5.4 Magnetic ceramics (ferrites)
- •5.5 Superconducting ceramics
- •5.6 Ceramics from neoxena refractory compounds
- •Conclusion
- •Literature
- •Composite silicate materials
1.5 Composite materials
In fibrous composites the matrix, often plastic, reinforced with:
1) high strength fibers;
2) wire;
3) whisker crystals.
The idea of creating a fiber-reinforced structures is not to exclude plastic deformation of the matrix material, and that when its deformation was to ensure that the loading fibers and used their high strength.
Mechanical properties of high-strength materials are defined by the presence of surface defects (cuts, cracks, etc.). Near the vertices of these defects under loading by concentrated internal stresses, which depend on the external applied stress, the crack depth and the radius of curvature at the crack tip. For brittle materials the stress concentration factor is equal to the CCS = 102-103. In this case, under the action of the already relatively small mean stresses at the fracture tip of the tensile stresses reach the limiting values and the material collapses.
There is a critical crack length at which there is a tendency to unlimited growth, leading to destruction of the material. Important is the fact that the corresponding critical voltage depends on the absolute size of the crack. Substances of a brittle material with high reproducible strength can be mainly in the form of fibers.
This is because fiber is much less sensitive to their existing defects than monolithic products. Because of the geometry of the fiber cracks in them should be either short, or to be predominantly parallel to the longitudinal axis of the fibers and therefore relatively safe.
The product with high strength (e.g., rope) can be obtained by combining the parallel fibers arranged properly in space. In the rope fiber loaded mainly tensile stresses. When combining the fibers in the product by the relevant navipac) tension between the individual fibers are generated due to sliding friction that occurs when stretching the rope.
In the manufacture and operation of ropes of fiber in them are subject to bending, the mutual friction, which leads to loss of strength, and sometimes the inability to use them. For example, high strength fibers (glass, carbon, boron) are very sensitive to surface damage, and cannot be applied to the rope, not using an environment that would protect the surface of the fibers and tied them together. This environment can be a polymeric material or plastic metal.
If non-continuous fibers (as in ropes), and the combined binding of short (discontinuous, discrete) fibers, and it preserves the principle of fiber reinforcement. It is that during loading of the composite at the interface of the matrix with the fiber shear stresses arise, which lead to the complete loading of the fibers. The peculiarity of the fibrous composite structure is uniform distribution of high strength, high modulus fibers in a plastic matrix.
Mechanical properties of ECM are determined by three main parameters:
1) high strength reinforcing fibers;
2) stiffness matrix;
3) bond strength at the matrix-fiber.
The ratio of these three parameters characterizes the whole complex of mechanical properties of the material and the mechanism of its destruction.
The performance of the VCR depends on the correct choice of initial components and rational technology of production, providing a strong bond between the components while maintaining the original properties.
Reinforcing fibres used in structural composites have to meet the complex operational and technological requirements. The former include requirements for:
1) strength;
2) rigidity;
3) density;
4) stability properties in a certain temperature range;
5) chemical resistance, etc.
Theoretical strength of materials σм increases with increasing elastic modulus E and surface energy γ of a substance and decreases with increasing distance A0 between the adjacent atomic planes A0. Therefore, high strength solid body should have a high elastic modulus and surface energy and perhaps a larger number of atoms per unit volume. These requirements satisfy Ve, b, C, N2, O2, Al and Si (7 items, the lightest in the Periodic system D. I. Mendeleev). The most durable materials always contain one of these elements, and often consist only of these elements.
When you create a VCR apply high strength glass, carbon, boron and organic fibers, metal wire and fibers and whiskers of number of carbides, oxides, nitrides and other compounds (SiC, SiO2, Al2O3, Si3N4).
The processability of the fibers determines the possibility of creating a high performance manufacturing process of the products based on them. An important requirement is the compatibility of the fibers with the matrix material, i.e. the possibility of achieving a lasting connection, the fiber – matrix under conditions allowing the preservation of the original values of the mechanical properties of components.
Compare DCM and ECM. In DCM, the optimal concentration of the dispersed phase is considered to be 2-7%. The dispersed particles in these materials, in contrast to fibers create only "indirect" strengthening, i.e. thanks to their presence stabiliziruemost structure formed during technical processing. A distinctive feature of the VCR – anisotropy of properties due to the predominant arrangement of fibres in a particular direction. DKM have the same properties in all directions, so the behaviour of the dispersed particles have an equiaxed shape.