Structure and Tribotechnical Properties of Polymer Composite Materials Based on Polytetrafluoroethylene and Palygorskite

Polytetrafluoroethylene (PTFE) has a low friction coefficient and high chemical inertness, which makes it popular for the manufacture of tribological materials. However, its main disadvantage is low wear resistance. To improve the characteristics of PTFE, fillers are used, among which natural silicates, including palygorskite, are promising due to their availability, mechanical strength and ability to improve tribological properties. Thus, the aim of the work is to develop polymer composite materials based on PTFE and natural palygorskite silicate with improved tribological characteristics.

The starting materials were PTFE powder grade PN-90 and natural palygorskite of Ural origin. Structural analysis of the samples was performed using IR spectroscopy and scanning electron microscopy with energydispersive analysis, hardness was measured using the Shore A method. The results showed a significant improvement in the tribological characteristics of composites with palygorskite compared to the original PTFE. With the addition of 5 wt. % of mechanically activated palygorskite, the wear rate decreased from 120 mg/h to 0.36 mg/h, and wear resistance increased 330 times. The friction coefficient slightly increases, but remains at a fairly low level, which is due to changes in the microstructure of the friction surface. The results of the conducted studies of the friction surface of composite samples confirm the formation of a strong wear-resistant surface layer (secondary structure). The resulting composites are promising for use in friction units in engineering and industrial equipment, where high wear resistance is required at a low friction coefficient.

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