Microstructure and wear resistance of thermal sprayed steel coatings ion beam implanted with nitrogen

In the present study, the high-current-density nitrogen ion implantation technique is applied to enhance mechanical properties of thermal sprayed steel coatings. XRD measurements and optical microscopy of ion implanted coatings show clearly the presence of nitrogen solid solutions and precipitates of new phases in the surface layers of coatings. Phases formed are controlled by the temperature of ion beam processing, initial chemical composition and microstructure of coatings. Wear tests demonstrate that properly selected parameters of ion implantation dramatically improve wear and score-resistance of coatings. The influence of the microstructure and phase composition of nitrogen ion implanted layers on tribological properties is discussed.     

Unlubricated sliding and rolling wear of thermoplastic dynamic vulcanizates (Santoprene) against steel

The friction, sliding and rolling wear characteristics of thermoplastic dynamic vulcanizates (TPV; Santoprene^® grades), composed of polypropylene (PP), ethylene/propylene/diene rubber (EPDM) and extender oil, were studied against steel counterparts in dry condition. The composition and basic mechanical properties of the TPV of various hardness (Shore A = 60°, 70° and 80°) were evaluated. The wear performance of the TPVs was investigated in different tribotests, viz. pin-on-plate (POP), cylinder-on-plate (fretting) and rolling ball-on-plate (RBOP), whereby “plate” was always the rubber. From the above tests the coefficient of friction (COF) and specific wear rate were determined. It was established that with increasing hardness usually both COF and the specific wear rate were reduced. Values of the COF and wear rate depended strongly on the configuration and testing parameters of the related tribotests. The wear mechanisms were concluded by inspecting the worn surfaces by white light profilometry and scanning electron microscopy (SEM), respectively, and discussed.