Corrosion and tribological properties of a composite based on aluminum with graphite particles
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CORROSION AND TRIBOLOGICAL PROPERTIES OF A COMPOSITE BASED ON ALUMINUM WITH GRAPHITE PARTICLES O. A. Shcherets’kyi, V. L. Lakhnenko, and V. O. Shcherets’kyi We study the corrosion resistance and tribological characteristics of composite materials based on an aluminum–silicon alloy with dispersed metallized graphite particles. Graphite decreases the friction coefficient and makes the wear resistance of materials 3–5 times higher as compared with the matrix alloy without decreasing its corrosion resistance.
The contemporary rapid development of engineering requires more and more perfect tribological materials. Indeed, the specific loads increase, the media become more aggressive, and the temperature conditions of operation become more severe. The problems of reduction of the weight of structures and increase of their service life, reliability, and stability of properties of the materials become more and more urgent. At the same time, the possibilities of improving the properties of standard alloys are practically exhausted. This is why the materials with heterogeneous and metastable structures are now used more and more extensively. As promising heterogeneous materials, we can mention, e.g., composite materials (CM) based on aluminum with dispersed graphite particles [1]. To obtain materials of this sort whose properties remain constant in the process of operation, one must solve numerous complicated technological problems. Thus, it is necessary, on the one hand, to get strong adhesive bonds between the dispersed particles and the matrix and, on the other hand, to prevent the formation of harmful compounds, which may either worsen the physicomechanical and tribological properties of the CM or lead to the degradation of the properties of materials in the process of operation, on the interfaces. In this case, one may also observe the formation of secondary structures which either improve the tribological characteristics of the material or, vice versa, significantly deteriorate these characteristics. Pure aluminum is characterized by a fairly high corrosion resistance due to the oxide film formed on its surface. However, depending on the type of alloying and reinforcement, this film may become much thinner. The composite materials based on aluminum alloys with dispersed graphite particles are, in fact, nonequilibrium systems characterized by a developed net of interfaces formed according to the gradients of chemical potentials. The difference between the chemical potentials of the matrix and the phase used for reinforcement is the driving force of the interaction between the phases and, in particular, of the mutual diffusion and chemical reactions. The interphase interaction directly affects the strength of the bonds between the components of CM and corrosion resistance specifying not only the properties of materials but also the possibility of their preparation and application. Therefore, for the determination of the optimal technological parameters of the production of CM, one must know the regu
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