OBRABOTKAMETALLOV MATERIAL SCIENCE Том 23 № 3 2021 EQUIPMEN . INSTRUM TS Vol. 4 No. 4 2022 Fig. 2. Sample shape and dimensions the sample are shown in Figure 2. The samples were manufactured by injection molding, followed by thermal and mechanical processing. The roughness of the friction surfaces of all test samples and counterbodies corresponded to class 7 (Ra = 0.8 μm). Test method. Before the start of the experiment, the sample and the counterbody were kept for 24 hours in a sea water simulator, then degreased with gasoline and acetone. For all variants of friction pairs, comparative tests were carried out at the following modes: - specific load Psp = 4.5 MPa; - linear speed along the average radius of the sample V = 0.14 m/s. The experiment lasted 11 hours. Current measurements were made every 1 hour during the running-in of the samples in order to determine the point of transition of the running-in mode to the stationary (steady-state) wear mode and after 6 hours – after the stabilization of the process. The linear wear of the material was measured on a vertical optimeter with an accuracy of 0.001 mm on three friction areas (A, B, C) separately and averaged. Results and Discussion The results of wear over time are shown in Table 1; according to the averaged values of three tests (Experiments), its graphical representation is presented in the form of histograms (Figure 3). Table 1 and Figure 3 show that the materials of the Maslyanit group have better wear resistance than pure Polyamide P-610. It should be assumed that the reason for the high wear resistance of Maslyanit D and Maslyanit 12 having the same polyamide base (matrix) is the presence of both solid and grease oil in its compositions, which simultaneously act as a plasticizer. The fillers of these compositions are fine metal powders, which increase the thermal conductivity of the material and reduce local temperatures in the friction zone [18]. In addition, the particles of these powders, being the centers of crystal formation, increase the crystalline phase of the material, which has a positive effect on its wear resistance [18, 19]. Comparing Maslyanites with each other, it should be noted that for Maslyanit D, the wear rate stabilizes after surface running-in, while for Maslyanit 12, even after the experimental time (11 hours), there is a large scatter of this evaluation parameter: zero wear when working with steel in one of the experiments Fig. 3. Wear rates of metal-polymer friction pairs in a sea water simulator
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