No abstract

Nanostructured NbSi 2 powders plasma sprayed on to Ti-6Al-4V substrates were characterized in this research. After preparation of the nanostructured NbSi 2 powders by mechanical alloying of an Nb-Si powder mixture, agglomeration was performed to obtain a particle size suitable for spraying. The agglomerated powders were then sprayed by atmospheric plasma spraying. Structural transformation of the powders and morphological and mechanical changes of the coatings were examined by use of x-ray diffraction analysis, scanning electron microscopy, energy dispersive spectroscopy, and microhardness testing. During milling, NbSi 2 intermetallic with a grain size of approximately 15 nm was gradually formed. After plasma spraying, a coating of hardness 550 ± 8 HV with a uniform nanocrystalline structure, low oxide content, low porosity, and a good adhesion to the substrate was obtained. No phase change occurred after spraying and the NbSi 2 compound remained nanostructured with a grain size of approximately 82 nm.

No abstract

Ti-6Al-4V alloys are widely used in aerospace industries because of their high specific strength. However, they have poor wear resistance. Plasma spray coatings were investigated as a way to improve the wear resistance of this alloy. In this paper, nanostructured NbSi 2 and NbSi 2 -Al 2 O 3 coatings were employed to enhance the tribological properties of Ti-6Al-4V. Atmospheric plasma spraying process was used for coating deposition. The structural transformation of coatings was examined by X-ray diffraction test. The pin-on-disk tribometer was used to carry out wear tests under dry sliding conditions and the worn surfaces and wear debris were examined by scanning electron microscopy , compositional analyses and microhardness tests. The tribological test results showed that for the investigated conditions, both coatings had satisfactory values of friction and wear resistance and they could be suitable candidates for Ti-6Al-4V material. Finally, it was concluded that NbSi 2 -Al 2 O 3 nanocomposite coated sample showed maximum hardness and highest wear resistance.

No abstract