Increasing of wear resistance of responsible parts of the hydraulic breaker by ion-plasma treatment

Abstract

During operation, parts of the hydraulic hammer are subjected to intense abrasive wear, which leads to a decrease in the duration of their work. The issue of increasing wear resistance occupies a special place in solving the problem of ensuring the necessary resource of these parts. In accordance with the literature data, as well as on the basis of analysis of many years of experience in operating hydraulic hammers, many methods of volumetric and surface hardening of parts are used that do not give a significant effect.Therefore, it became relevant to attract new methods of surface hardening. These methods include ion-plasma chromium plating. As the tasks of the work, a detailed analysis of the damaged working surfaces of the hydraulic hammer parts was provided; the study of changes in the structure and properties of hardened surface areas during operation; development of the hardening process, providing increased wear resistance of parts as a result of ion-plasma chromium plating. We investigated the condition of the working surface of the critical parts of the hydraulic hammer - the hammer and peaks - after hardening and operation. Data were obtained on the nature and intensity of wear in the zones and sections of each part. High-quality chromium coatings were obtained at substrate temperatures not lower than 80–100 ° С. Based on experimental studies, the effect of ion-plasma chromium plating on the wear resistance and mechanical properties of hydraulic hammer parts is proved, and structural changes in the material are analyzed. After operation, the surface of the part may have defects such as scuffing, cracks along the axis of the part, loss of metal mass (decrease in coating thickness), as well as local hardening and deformation of the metal. Ion-plasma chrome plating of parts according to the proposed technology increased their wear resistance by 1.75 times compared with unstressed. The technology of ion-plasma chromium plating ensures the operation of hardened parts without chips and without chipping. In areas of damage to parts, zones of structural transformations characteristic of secondary hardening phenomena are noted.