Tribological properties of thermal-sprayed Magneli-type coatings with different stoichometries (Ti sub n O sub 2n-1 )

• Published in: Surface & coatings technology 2001-05, Vol.140 (2), p.76-81
• Main Authors: Storz, O, Gasthuber, H, Woydt, M
• Format: Article
• Language: English
• ISSN: 0257-8972

This paper summarizes results on the possibility of coating aluminium with titania-based Magneli-type coatings by thermal spraying, and the tribological properties of these coatings. For this purpose, a spray powder with a defined phase composition was applied on AlMg substrates by atmospheric plasma spraying. Crystalline Magneli phases of the type Ti sub n O sub 2n-1 with a crystallographic shear structure could be identified after spraying in the coating by means of x-ray diffraction. Dry sliding experiments were conducted on a high-temperature pin-on-disk test rig against polycrystalline alumina at 23 and 400 deg C up to a sliding distance of 2000 m at 1 m/s. The coefficient of friction (COF) remains high, at between 0.7-0.8 for all tests. The best wear results are achieved for the Ti sub 6 O sub 11 coatings, showing wear rates down to 1.2x10 exp -6 mm exp 3 /N m. The tribological behavior of the sprayed coatings indicates strong anti-wear properties under dry sliding conditions. Under mixed /boundary-lubricated conditions, the interaction of a low-additive polyalkyleneglycol (PAG100) with Magneli-type phases results in very low friction and wear coefficients in the range of 10 exp -10 mm exp 3 /N m.