Influence of curent density and bath composition on properties of Ni/PtFe composite coatings
Maria Trzaska, Beata Kucharska Politechnika Warszawska, Wydział Inżynierii Materiałowej, ul. Wołoska 141, 02-507 Warszawa, Poland
Quarterly No. 1, 2008 pages 77-81
DOI:
keywords: nickel coating, composite Ni/PTFE coating, electrochemical method, microhardness, tribological properties
abstract Composite layers with nickel matrix and PTFE disperse phase deposited by the electrochemical method have been the subject of the present investigations. The coatings were deposited from a low concentration Watts bath with organic additives on steel substrate (St3S). Investigations include composite coatings of micro- and nano-crystalline structure of nickel matrix and micrometric dimensions particles of disperse phase of polytetrafluoroethylene - PTFE. Micro- and nano-crystaline structures of nickel coatings were also investigated to have a comparison with composite layers. The used PTFE was in a powder form of particle dimensions in the range of 1030 μm. The topography and morphology of produced layers are presented. The influence of current density, contents of PTFE in the bath and the additives of organic substance on the structure, the contents of polymer phase in composite material and tribological properties of produced layers have been studied. The method of computer analysis of images was applied to determine the content of the dispersed phase of PTFE in the composite material. The microhardness of the materials has been investigated by using the Vicker’s method. Tribological investigations were performed by tester T04 without lubrications. The course of wear tests as time functions of duration of attempt of the Ni and Ni/PTFE layers were investigated. The morphologies of nickel and composite layers after wear tests are shown were presented. In conclusion, it has been checked that the composite Ni/PTFE layers importantly decreases their abrasion wear in comparison with the nickel layers.