PSI - Issue 50

A.A. Ushkanov et al. / Procedia Structural Integrity 50 (2023) 294–298 A.A. Ushkanov, A.A. Okhlopkova, A.P. Ammosova / Structural Integrity Procedia 00 (2022) 000 – 000

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with elasticity and strength, which are not inferior in performance even to some alloys and metals. Among polymers, polytetrafluoroethylene (PTFE) has the most preferred set of properties (Mashkov (2010), Vasilev et al. 2019)). As you know, in recent times, the Arctic ice has begun to melt rapidly, which indicates climate change, which includes extreme weather events, such as displacement of populations and habitats of wildlife, floods and a number of other irreversible impacts. It has been found that the Arctic is warming three times faster than the world average. Environmental protection is the most important condition for the development and existence of the Arctic. Basalt fiber is the only sustainable, non-polluting fiberglass product that is made from molten volcanic rock. The mechanical properties of basalt fibers are much higher than those of glass fibers, and, close to the properties of carbon fibers, some even exceed the corresponding values of carbon fibers. In addition, basalt fibers do not contain any other additives in the same manufacturing process, which gives them an additional cost advantage. Due to its high performance-to-price ratio, basalt fibers are often used as an inexpensive replacement for carbon fibers in many applications (Wang et al. (2014)). With the intensive development of the social economy, the understanding and application of PTFE fiber fillers, in particular basalt fiber, is deepening, and the market demand for products based on it is growing rapidly. Research on basalt fiber is still in its early stages, but studying the characteristics of PCM based on it is of great strategic importance (Li et al. (2018)). 2. Experiment 2.1. Materials and Methods PTFE brand PN- 90, produced by JSC « HaloPoly mer» GOST 10007-80. Molecular weight - 100-500 thousand, degree of crystallinity before sintering - 95-98%, after sintering - 50-70%, crystal melting point 327 °C, glass transition temperature of amorphous regions - from -100 to -120 °C, average size particles 46-137 microns. Basalt roving, known as the «silk of the volcanic rock» of the 21st century, is also called gold fiber because of it is color. Manufactured by Technology of Basalt Materials LLC (Pokrovsk, Republic of Sakha (Yakutia)). The basalt roving was passed through a Fritsch Pulverizette 15 grinding mill with a 0.25 mm sieve installed. The length of the obtained fibers varies within 100-400 microns, and their diameter is 8.0-10.0 microns. Carbon fibers of the "Belum" brand produced by JSC « SvetlogorskKhimvolokono » were modified by plasma chemical treatment in an environment of organofluorine compounds. The fiber's width and length are 8 –10 µm and 50 –500 µm, respectively (Vasilev et al. (2017)). Composites for testing were obtained by dry mixing of pre- dried components (180 º С for 4 hours for PTFE and 120 º С for 2.5 hours for fibers) followed by molding, after which they were sintered in a muffle furnace at a temperature of 375 º С and calibrated to remove the effects of thermal shrinkage. The study of physical and mechanical properties was carried out on a universal testing machine AUTOGRAF (Shimadzu, Kyoto, Japan) at room temperature. Tensile strength, elongation at break and tensile modulus were determined according to GOST 11262-2017, the speed of movement of the movable grippers was 50 mm/min, a sample in the form of a blade was type 5; The compression test was carried out in accordance with GOST 4651 2014, the speed of the traverses was 1 mm/min, the percentage of deviation at a given speed was up to ± 20%. Tribological parameters were determined on a universal testing machine UMT-3 (CETR, Mountain View, CA, USA). The coefficient of friction was determined according to GOST 11629. Scheme of friction "finger-disk". Samples with a diameter of 10.00 ± 0.02 mm and a height of 20.0 ± 0.2 mm. The counterbody is a steel disk made of steel 45 with a hardness of 45 – 50 HRC, roughness Ra = 0.06 –0.08 µm. Normal loading force - 160 N, linear sliding speed - 0.2 m/s. The duration of the test is 3 hours. In the work by Alifanov et al. (2018) presents in detail the circuit diagram of the tribometer. The structure of friction surfaces and the supramolecular structure of the composites were studied using a JSM 7800F scanning electron microscope (SEM) (Jeol, Akishima, Japan). 3. RESULTS The table shows the results of physicomechanical and tribological studies of PTFE and composites based on it.