Structural and tribological properties of nanostructured supersonic cold sprayed Ni-20 wt.% Sn coatings

80-μm-thick nanostructured coatings consisting of a Ni solid solution, Ni3Sn, Ni3Sn2, and metastable NiSn intermetallic phases were deposited via supersonic cold spraying onto inconel 718 alloy substrates. These coatings have complex nanostructured metallurgical phases as revealed by transition electron microscopy, scanning electron microscopy, and x-ray diffraction techniques. Their mechanical properties were determined by nanoindentation measurements. Furthermore, the wear behavior of these nanostructured sprayed coatings was compared to the one of the industrial bulk or sprayed coated benchmark materials. It was found that the nanostructured coatings exhibit higher wear resistance than the industrial benchmarks, thanks to an appropriate balance of hard intermetallic phases and soft Ni matrix, as well as to their nanostructuring. Their frictional characteristics under reciprocating sliding are mainly determined by the formation of an oxide-based tribo-layer, which was analyzed by x-ray photoelectron spectroscopy. The role of intermetallic phases in these coatings on the friction and wear is also discussed.status: publishe

Structural and tribological properties of supersonic sprayed Fe-Cu-Al-Al₂O₃ nanostructured cermets

A nanostructured cermet coating consisting of alumina dispersed in a Fe–Cu–Al matrix was deposited by supersonic spraying. The experiments revealed a strong effect of deposition parameters and chemical composition of the powders on the structural characteristics of the Fe–Cu–Al + Al₂O₃ sprayed cermet. This cermet is made up of complex metallurgical phases as revealed by electron microscopy and X-ray diffraction. The mechanical properties of the different phases detected were determined by nanoindentation. Finally, the friction and wear behavior of this nanostructured sprayed cermet were compared to the ones of benchmark materials. It was found that the Fe–Cu–Al + Al₂O₃ cermet coating exhibit better tribological properties than the benchmark materials thanks to an appropriate balance of hard and soft phases, and a nanostructuring. The wear mechanism was investigated to establish a ‘structure–property’ relationship for this type of nanostructured cermet coatings.status: publishe