TRIBOLOGICAL BEHAVIOR OF TIC TAC-REINFORCED CERMET PLASMA-SPRAYED COATINGS TESTED AGAINST SAPPHIRE/

This paper deals with the investigation of the tribological behavior o f TiC/TaC reinforced NiCrMo and Mo plasma sprayed coatings. The coatin gs were classified with respect to friction and wear behavior in pin-o n-disk tests. The NiCrMo-based coatings, with better carbide-metal mat rix binding than the Mo-based coatings, are also the more wear resista nt. The NiCrMo-based coatings show a better functionality, when the re inforcing particles are a solid solution of TiC and TaC, than the coat ings with only TiC or TaC reinforcement. Abrasion, adhesion and fractu re assisted wear were observed to be the primary wear mechanisms invol ved in these complex TiC/TaC reinforced coatings, as revealed by SEM i nvestigation of the wear tracks and the debris. The extent of each mec hanism appears to be influenced by the carbide-matrix interface streng th. The processing to structure and functionality relationships highli ght the key parameters in the effort to design high wear resistant coa tings.