In this work the possibility of using TiO2 coating as a barrier between carbon fiber and an aluminum matrix in a Cf/Al composite was studied. Specimens of a composite with a matrix of Al-6Mg alloy were obtained by the method of liquid-phase infiltration under pressure. As a reinforcing component was used continuous uncoated and titanium dioxide coated carbon fibers. TiO2 coating on carbon fiber preform were prepared by sol–gel method. The protective properties of the coating and the mechanical properties of the composite at three-point bending were evaluated. Microstructural and fractographic analyzes were performed. It was established that the barrier coating made it possible to increase the strength of the composite more than 2.5 times from 250 MPa to 660 MPa.

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Abstract. The paper presents the results of studies on the stress-strain state of composite wing spars with different lay-up structures. The object of research is a U-shaped cross-section composite wing spar. On the basis of the analysis of the stress-strain state, the most favorable structure of a wing spar from the viewpoint of minimizing the risk of stress state and providing the highest stiffness. Recommendations are given on layup structure stacking (compared with typical structures) for more effective perception of external loads by a wing spar.

This paper deals with the development of carbon fiber coatings that act as diffusion barrier, and the role of the weak boundaries in the metal matrix composites. The developed coating will be a cost effective alternative to CVD-coatings. The paper considers the temperature dependence of the structure of SiO2-sol and the coating thickness on the surface of the carbon fibers formed by sol-gel method. Detected sol temperature range optimum for coating. Possible reasons for the observed phenomena are proposed.

In connection with the prospect of using metal matrix composites for various types of structural applications (in particular, thermally loaded elements of aviation and rocket-space technologies), recently more and more research has been focused on exploring the possibility of bonding controlling at a fiber-matrix interface, which, as a rule, is a weak point for composite materials of this type. In the case of carbon-aluminum composites, in order to fully reveal their strength properties, it is necessary to solve the problem with the formation of brittle aluminum carbide at the interface, drastically reducing the mechanical characteristics of composite materials. There are several ways to solve this problem, but the most promising is the application of barrier coatings, in particular oxide coatings, on the surface of the fibers. In this work, we have investigated the effect of single-layer, two-layer and three-layer coatings of titanium dioxide TiO 2 deposited on carbon fibers by the solgel method, and heat treatment at 150°С, 350°С and 550°С for 1 hour on the strength of carbon-aluminum composites at three-point bending. It has been found that when using the sol-gel technology, titanium dioxide covers the fibers surface completely. In the microstructure of composites reinforced with uncoated and coated fibers, there are no pores or areas without impregnation. On average, the bending strength for carbon-aluminum specimens reinforced with uncoated fibers increases significantly after annealing, and the titanium dioxide coating in turn also contributes to an increase in the strength properties of the carbon-aluminum composite.