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Published data on the use of high-porosity low-weight carbon-bonded carbon-fiber-reinforced (CBCR) composite structural materials in high-temperature technology are generalized. It is shown that large-scale structures can be created from CBCR composites at a quite small material weight consumption. Such structures are characterized by low weight and small temperature-induced deformations, which ensure long service life and reliable thermal isolation, for example, of metal furnace shells. Methods for the assembly of CBCR structures by mechanical means or using heat-resistant glues are proposed.

The erection of refractory structures made of carbon-bearing materials involves assembling the elements-of the structure so as to ensure their durability under significant mechanical and thermal loads and allow the formation of supports and cbznr~ls for conductors within the structure. The method of assembly must also not unduly complicate the design and maintenance of the structure for service at temperatures above the melting points of most metals and alloys.The main methods that meet the stringent requirements for assembling carbon-bearing structural elements are bonding with high-temperature adhesives and mechanical fastening. In contrast to the adhesives used for metals and plastics, these adhesives --as the carbonized binders of the structural materials themselves --must have a high coke number, adequate viscosity, and wettability sufficient for penetrating the pore space of the material, filling surface cavities, and forming carbonized structures that "bond" with the substrate as a result of adhesion. Thus, a carbonaceous composite is created in the adhesive joint, this composite making it possible to transmit mechanical loads from one part to another at temperatures within the range 1000-1500"C.The ,lamzte tensile strength of adhesively joined carbon surfaces is very low --3-4 MPa. The strength of the joint is increased by reinforcing it with carbon powders, fine carbon fibers, or stronger powders of carbide-forming metals (silicon, ti~, zirconium) or their oxides. Disperse inclusions of carbides of these metals in the adhesive joint (boron carbide also being added in certain cases) increase the adhesive strength of the interface to 7-9 MPa, but their main importance is that they significantly reduce the deformation of the joint. Carbides of the indicated metals have an elastic modulus of 3500-4600 GPa, which is 10-15 times greater than the volumes of carbon-bearing materials joined together in the composite. As a result, on the average the stiffness of the adhesive joint as a whole rams out to be higher than the stiffnesses of the carbon-bearing parts being joined. There is a proportionate reduction in strain in the joint in the transmission of the external load. As regards choosing the optimum composition of composite joint and the optimum size of carbide particles, adequately sealing the cad~on-bearing structural elements within the joint realizes conditions under which the cohesive strength of the joined elements sometimes turns out to be lower than the adhesive strength of the joint itself.Additions of heat-resistant and high-strength carbides not only change the character of deformation of the components within the adhesive joint --reducing shear strain at the interfaces of the carbon surfaces to safe levels --but also improve the durability of the joint when subjected to oxidation at elevated temperatures. The same phenomenon is seen in high-temperature carbon-carbide composites. The actual strength of the joint is determined to a significant extent by the internal stresses in its vicinity, which i...

The main directions are considered for increasing the refractoriness of structural graphite materials, carbon-carbon composite materials (CCCM), and structures made of them. Practical examples are proposed for increasing the refractoriness of materials based on carbon in the application temperature range from 1200 to 1700°C. Results are provided for experimental study of four types of increased refractoriness. It is demonstrated that the contemporary direction of domestic work for increasing the refractoriness of structural graphite materials and CCCM agrees on the whole with a series of overseas achievements in this field.The increase in the cost of industrial energy resources has a marked effect on the cost of a most energy-consuming producing that relates to structural graphite materials, including carbon-carbon composite materials (CCCM). Therefore the task of determining the endurance of these materials during operation acquires even more importance. Graphite materials and CCCM are related to the most heat resistant structural materials, but their refractoriness in oxidizing atmospheres is inadequate.An increase in the operating capacity of structural graphite materials in high-temperature oxidizing atmospheres is the theme of an ever increasing stream of research. A comparatively more complex problem is provision of refractoriness for CCCM in a high-temperature oxidizing atmosphere. This is connected with the more marked difference in thermophysical, elastic and deformation properties of isotropic heat-resistant coatings and anisotropic surface layers for CCCM.The most important problem is increasing refractoriness of graphite materials and CCCM above 1500°C, when structural steels and heat-resistant alloys are not efficient or short-lived. Starting from these temperatures carbon material are oxidized by oxygen, water vapor, carbon dioxide, by a so-called diffusion mechanism [1]. Here reaction with an oxidizing agent proceeds not only over the surface of a component with a specific surface of about 0.5 m 2 /g, but also through the porous volume of a component with a specific surface up to 2 -8 m 2 /g.

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