Фреттинг-изнашивание наводороженного циркониевого сплава Э125, упрочненного диффузионными покрытиями

Abstract

Protective coatings that improve the corrosion resistance of the E125 zirconium alloy under conditions of the combined effect of a hydrogen-containing medium and friction wear have been investigated. The formation of coatings on the surface of the samples was carried out by thermal diffusion treatment in powder saturating media with halogen activation at temperatures from 400°C to 950°C. The resulting coatings were formed as a result of the processes of oxidation, siliconization, and nitrocarburizing. Wear tests were carried out on a SRV Testsystem multifunctional testing system according to the disk-ball scheme without lubrication. Cathodic hydrogenation of the samples was carried out in an electrolyte solution containing a single normal sulfuric acid solution at room temperature. The cathodic current density was from 20 to 500 mA / cm2. The hydrogen concentration in the samples was determined on a highly sensitive G8 Galileo H gas analyzer by melting the samples in a carrier gas flow. As a result of the study, it was shown that the wear of the coated specimens after siliconizing and nitrocarburizing is three times lower than that of the original uncoated specimen. Oxidation leads to a significant, more than fivefold, increase in the amount of wear, in comparison with the same initial sample. Hydrogenation of the surface of the samples allows not only to reduce the coefficient of friction, but also to reduce the amount of wear in the process of testing samples for fretting wear. This study makes it possible to obtain modified surfaces of zirconium samples that significantly improve the mechanical properties, as well as reduce the level of hydrogenation, and increase the performance of components made of zirconium alloys under conditions of increased friction.