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2004
Conference Paper
Titel
Tribological characterization of titanium suboxide coatings prepared by VPS spraying
Abstract
Titanium-containing materials are often characterized by a high wear resistance, which is proposed to be caused by the formation of titanium suboxides with a shear plane structure (Magnéli phases). Thermal spraying is one of many surface modification technologies that are widely used to prepare coatings made of titanium compouds or titanium-containing composite materials. In this study, titanium s uboxide coatings were prepared by vacuum plasma spraying (VPS) from a commercial fused and crushed powder and investigated as a "benchmark" for evaluation of tribological properties of other thermally sprayed titanium-containing coatings. The unlubricated tribological behavior of coated samples held against a stationary specimen of sintered polycrystalline alumina was characterized. Tribological behavior under mixed/boundary lubrication conditions was characterized with coated rotating specimens using different lubricants at a temperature of 170°C and a load of 50 N (sliding speed of 0.3 m/s and total sliding distance of 24 km). The stationary specimens were cast iron piston ring segments coated with commercial APS-sprayed Mo-NiCrBSi or HVOF-sprayed WC/Cr3C2-based hardmetal coatings. Some tests under mixed/boundary lubrication conditions were also performed under oscillating sliding conditions. Results of sliding tests performed in unlubricated and lubricated conditions are compared and discussed with pervious results obtained using these materials as coatings or monolithic ceramics.