## 3 Advantages of Composites over Traditional Materials
The Influence of Interfacial Interaction of Components in Carbon-Containing Composites on Their Physical and Mechanical Properties  
The interfacial interaction of the composite components sets its physical and mechanical properties: strength, hardness, fracture toughness, heat resistance, and others. When controlling the process of interfacial interaction for composites, one should consider the conditions for the compatibility of components and the stability of the interface between phases [103; 105; 108; 109]. When obtaining composites, where fibers are used as a hardener, the interfacial interaction must be limited since intense interaction leads to a deterioration in the final physical and mechanical properties. At high temperatures, chemical reactionscan occur at the composite interface. Under the condition that a chemical reaction occurs on the surface, the bond between the reinforcing component and the matrix becomes stronger. However, if the layer is thicker, the reaction products can, on the contrary, weaken the bond, up to the destruction of the fiber. Chemical interaction can occur both during the composites' preparation and during their high-temperature treatment [63; 104; 106]. From the point of view of boundary processes, there are three classes of fibrous composite materials [4; 5]; when the matrix and fiber: (i) are not mutually reactive and soluble, that is, they do not form solid solutions and chemical compounds; (ii) are not mutually reactive, but soluble, then they form solid solutions, but do not form chemical compounds; (iii) react with the formation of a chemical compound at the interface. Changes in the chemical composition occur at the phase boundary. The main task of the interface is to ensure the connection between the matrix and the hardener. Thus, the mechanical properties of the boundary region are very important, in particular, stability under various loading methods. In this area, the following types of bonding are distinguished [6]:  
1. Mechanical bonding due to friction forces. Such materials have low strength in transverse tension and longitudinal compression (composites of the first class). 2. Bond due to surface tension forces. It is typical for materials formed during wetting and dissolution without a chemical reaction. When wetting, a slight dissolution of the components occurs when the fibers are impregnated with a molten matrix (composites of the first and second classes). 3. Reactive bond during a chemical reaction at the interface, which results in the formation of other chemical compounds (composites of the third class). 4. Exchange-reaction bond. A kind of reaction bond in which a chemical reaction does not occur simultaneously but in several stages. 5. Oxide bond. A kind of reactive bond characteristic of composites reinforced with fibers or oxide particles. In composite materials with metal matrices, bonding is achieved through the formation of spinels at interphase boundaries or through an oxide film through which bonding occurs. The interaction between the metal and SWCNTs can lead to MWCNTs with open ends occurring [109; 110]. Contact interaction at the open ends of CNTs occurs due to the strong \(\sigma\)-bonds formation, which can lead to a reaction with the formation of metal carbide. The possibility of a chemical interaction between CNTs and fullerene with metal surfaces was experimentally shown in [108; 109; 110; 111]. The calculations showed that the binding energy of an Al atom with an ideal surface of an unmodified SWCNT did not exceed 0.4 kJ/mol or 4\(\cdot 10^{-3}\) eV due to weak \(\pi\)-bonds. The presence of oxygen-containing functional groups on the CNT surface has a significant effect on the interaction with some metal atoms [108; 109]. Firstly, metals create a covalent bond with oxygen, and secondly, groups containing oxygen create conditions for the convergence of the energies of the valence orbitals of metal and CNT atoms, contributing to their greater overlap.