Application of UNSM (Ultrasonic Nanocrystal Surface Modification) Technology for Prolonging Service Life of Journal Bearing o

Author:  Amanov, Cho, Kim, Pyun
Source:  Conf Proc 2011: ICSP-11 South Bend, IN USA (pgs. 393-398)
Doc ID:  2011066
Year of Publication:  2011
Abstract:  
Abstract Journal bearings (JBs) of railroad axle are safety critical components of railroad operation, so they have to be checked and replaced periodically. Sixty seven damaged bearings were analyzed and categorized into eleven known failure modes. Damage accumulation due to fatigue, plastic deformation and wear significantly reduces the service life of JBs of a railroad axle. Ultrasonic nanocrystal surface modification (UNSM) technology can improve surface integrity and surface hardness, and induces compressive residual stress in surface layers. Therefore, UNSM technology was applied to disk specimens, which simulated the working conditions of journal bearings in order to extend its service life, to reduce friction and to improve wear resistance. The result of disk-on-disk friction and time-to-beginning-surface-scratch (TTBSS) tests showed that friction coefficient of the UNSM-treated surfaces was reduced by 30% and TTBSS was prolonged by 55%. In addition, pin-on-disk wear test was conducted on the UNSM-treated and polished surface specimens and its results showed that wear volume loss of the UNSM-treated surface specimen was reduced by 45%. The basic mechanism and effects of UNSM technology are also explained. Keywords Journal bearing, friction, wear, Ultrasonic nanocrystal surface modification (UNSM).