Author(s) | Collection number | Pages | Download abstract | Download full text |
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Manko O. V., Palamar O. O., Stetsko A. Ye. | № 1 (56) | 61-70 |
In the article, the manifestations of the structural adaptability effect in the friction pair “roller-sleeve” have been considered, proceeding from the processes of formation of the structure of the strengthened coating and its tribological research. The purpose of the work is an attempt to interpret the phenomenon that has manifested itself in the running-in process of friction pair, when the sleeve is strengthened through a combined strengthening treatment, and the roller (counterbody) — by diffusion boronization.
When calculating the intensity of wearout of a friction pair, which has been carried out according to numerical data of weight wear, the attention has been attracted to the steady cases of the absence of weight wear in the “body – counterbody” system, which have acquired a non-periodical character. A constant phenomenon of falling (disappearance) of the intensity of wear can be traced simultaneously for both the body and counterbody, and for each element of the friction pair in particular. As a result, the intensity of the wearout of the resulting coating (and counterbody) is sometimes absent.
In the case of the received coating, we can state the presence of metastability of the matrix of the outer composite zone. The reasons that lead to the formation of the unbalanced state of the matrix are the initial conditions of diffusion, the effect of the liquid metal phase, the rate of formation of the carbide phase, which leads to a considerable distortion of the crystal lattice of the matrix and, accordingly, the accumulation of latent energy.
Strong unbalance of the matrix of the external composite coating zone under conditions of external influences (under rigid conditions of reversible friction in limited contact spots) may be accompanied by a transition to an excited state, which, along with the phenomenon of falling wearout intensity, is another sign of the effect of structural adaptability. The excited state is characterized by a peculiar “liquefaction” of the surface layers on the mesolevel (0.1...1.5 microns), and thus contributes to the implementation of the rule of positive gradient of shear deformations. Speaking about the influence of structural adaptability, manifestations of this phenomenon can be explained only by the properties of the soft matrix of the composition zone. The presence of a heterogeneous structure of this zone with uneven placement of carbide grains greatly impedes the “pure” manifestations of this phenomenon and complicates the overall pattern of passing as a running-in, as well as an fixed wearout.
Keywords: reversible friction, chemical and thermal treatment, tribosystem, intensity of wear, roughness, dissipative structures, diffusion layer.