OBRABOTKAMETALLOV Vol. 23 No. 3 2021 MATERIAL SCIENCE EQUIPMENT. INSTRUMENTS 4 4 2 Ta b l e 1 The results of wear resistance of metal-polymer friction pair in the sea water simulator (wear rate, µm/h) Sample material Steel Bronze Titanium alloy Polyamide P-610 Experiment 1 25.0 11.6 90.3 Experiment 2 69.0 35.6 210.0 Experiment 3 21.4 5.9 223.0 Maslyanit D Experiment 1 5.2 9.6 26.5 Experiment 2 5.2 1.5 10.2 Experiment 3 0.5 3.1 8.8 Maslyanit 12 Experiment 1 0.0 0.72 8.0 Experiment 2 3.3 17.2 42.4 Experiment 3 174.0 0.055 3.7 and high (174 µm/h) in the other (Table 1). Obviously, this “false wearless” can be explained by the presence of iron minium, which generates a thin film on the friction surface. As is known, iron minium – iron oxide Fe2O3 – is used to create the corrosion-resistant and moisture-proof coating of structures. In case of friction in salt water, a thin tear-resistant film is most likely generated on the friction surface. It should be noted that complex physicochemical changes associated with the development of competing processes of destruction and structuring occur during the formation of the friction transfer film in the surface layer of the polymer body. From the point of view of thermodynamics and structural and energy self-organization, the initial stage of friction (running-in) is characterized by the intensive destruction of the initial structures and formation of new, so-called tribostructures with higher antifriction properties. At the same time, some kind of the self-organization of the tribosystem takes place [18–21, 22]. All three tested materials (Figure 3) have significantly worse results in friction with titanium than in friction with steel and bronze; this is typical for titanium alloys [21, 23]. The antifriction properties of Maslyanites during friction with all metal counterbodies are better than that of Polyamide P-610 (Figures 4–6). In addition, Polyamide P-610, within the entire resource of the experimental time (11 hours), when tested in tandemwith steel and bronze, is characterized by a constant increase in the friction coefficient instead of its stabilization. The friction coefficient peak for Polyamide P-610 (Figure 6) in tandem with a titanium counterbody (increasing to 0.7) is correlated with the wear test results (Figure 3), showing the limit value of the wear rate (178 µm/h) for all ex-applications. Destructive processes in the friction zone can explain a sharp decrease in the friction coefficient during its catastrophic wear. Fig. 4. Dynamics of friction coefficients values of a pair: stainless steel 12Cr18Ni9Ti and polymeric material during the completion of the running-in process
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