Tribological Investigation of Detonation Sprayed Ni-Cr And Al 2 O 3 13Tio2 Coatings On Grey Cast Iron To Enhance Its Wear Resistance
This paper is concerned with the investigation of the capability of Detonation sprayed Ni-Cr And Al2O3 13TiO2 coatings to improve the tribological and mechanical properties of grey cast iron. The present study describes and compares the mechanical and tribological properties of NiCr and Al2O3 13TiO2 D-Sprayed coatings deposited on two different substrates (GI250 and GIHC) Experiments using a tribometer (pin on disc) is performed in order to evaluate the wear properties. The coating microstructures were characterised by SEM and EDAX. Cumulative weight analysis is done to compare the wear loss in weight and its concluded Al2O3 13TiO2 form a good bond with GI250 using Detonation spray process.
Wear behaviour of thermally sprayed ceramic oxide coatings
Abstract The wear resistance of plasma-sprayed ceramic coatings (Al2O3, Al2O3–13%TiO2, Cr2O3) has been investigated through pin-on-disk and dry sand-steel wheel tests, has been correlated to microstructural and micromechanical characteristics (microhardness, fracture toughness) and has been compared to well-known platings (such as Cr electroplating and electroless Ni) and HVOF-sprayed cermets (WC–17%Co, WC–10%Co–4%Cr). Plasma-sprayed ceramics are hard but brittle: dry particles abrasion occurs through splats detachment. The toughest coating (Al2O3) displays the highest wear resistance, which in fact overcomes HVOF-sprayed cermets and Cr electroplating, when a low number of wheel revolutions are considered. In pin-on-disk tests, no coating undergoes wear loss against the 100Cr6 ball, that possess lower hardness. Against the alumina ball, Al2O3 and Al2O3–TiO2 coatings show high wear rates and friction coefficients (due to chemical affinity), while Cr2O3 possesses better wear resistance, lower friction coefficient and inflicts less wear on the counterpart. Cr2O3 wear scar consists in plastically deformed splats and debris forming a quite adherent protective tribofilm.
Nuclear spin-lattice relaxation in transition metal compounds with local tetragonal symmetry.
We report on the various contributions to the total spin-lattice relaxation rate in metallic materials with local tetragonal symmetry. The analytical formulae are given in the tight-binding approximation. The calculations show the relation between various partial electron densities of states and corresponding contributions to the relaxation rates. The presented formulae can be used to compare theoretically calculated electron band structure parameters with those obtained from NMR spin-lattice relaxation time measurements.