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Streszczenie:
The paper investigated the effect of electrospark alloying (ESA) on the formation of wear-resistant molybdenum disulfide (MoS2) based coatings for use in face impulse seal (FIS) of pumping equipment operating under conditions of high temperatures, pressure, aggressive environments and radiation exposure. The coatings were obtained on samples of austenitic AISI 321 steel. Two sulfomolybdenation methods have been developed: the first method involves the preliminary application of a sulfur-containing paste before ESA processing with a molybdenum electrode; the second one involves applying the MoS₂ powder and subsequent ESA processing with a molybdenum electrode. The microstructure, microhardness, phase composition and tribological properties of the coatings have been investigated. It was established that the formed coating had a structure comprised of three layers. Those are a porous surface layer, a strengthened layer and a diffusion zone. The maximum microhardness reached 1127 HV at Wp = 3.4 J. The results of tribological tests according to the “ball-disk” scheme showed a decrease in the friction coefficient to 0.0078 on samples obtained by the first ESA method. The obtained results confirm the feasibility of using the ESA methods with the inclusion of molybdenum disulfide in order to increase the operational reliability and durability of FIS units under extreme operating conditions. The proposed technologies can be implemented in production of pumping equipment for nuclear, chemical and energy industries

Słowa kluczowe:
Electrospark alloying, Molybdenum disulfide, Face impulse seal, Tribotechnical coatings, AISI 321 steel