Experimental and Modeling Study of Sliding Wear Performance for Selected Molybdenum Stellite Alloys

Abstract

This thesis presents an experimental and modeling study of wear performance of molybdenum-containing Stellite alloys. Wear testing conditions are pin-on-disc type using a tungsten carbide ball against the Stellite alloys in dry-sliding mode at ambient temperature. Three variables are explored: (i) two rotational speeds, (ii) two normal loads, and (iii) various time durations (up to 60 hrs). A continuous test and an interrupted test at various intervals are introduced. The wear loss reduces across each of the alloys under all conditions for the interrupted test. Phase evaluation is studied using SEM, EDX and XRD techniques. Evaluation of the volume fraction of carbides reveals Stellite 21 to have ~4%, Stellite 720 to have ~70%, and Stellite 728 to have ~21%. A general model is developed for the alloys using the wear testing data and Archard's equation, which reveals Hardness is a significant factor in the wear of molybdenum Stellite alloys.