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.
Metallographic and SEM investigation of the microstructure of thermally sprayed coatings on steel substrates
Abstract Using optical microscopy and SEM microprobe analysis, an investigation of the microstructure of thermally sprayed alloy coatings on steel substrates has been carried out. Particular attention has been paid to the development and application of stereometric metallography for the estimation of volume parameters of the spherical grains observed in the structure of the thermally sprayed coatings. The spherical grains were formed from initial powder particles that reached the coated substrate in a semi-molten state, and thus are a kind of inhomogeneity, which could act as a concentrator of internal stresses in the coating. The results suggest that for flame spraying, the spherical grains result mainly from initial powder particles with higher than the average dimensions, whilst for the plasma spraying, the spherical particles are those with significant concentration deviations. Some important parameters (mean diameter, size distribution curves, volume fractions) of the spherical grains as estimated by the stereometric method of Scheil–Schwartz–Saltikow are given in the paper. The results give some additional information about the process of structure formation of thermally sprayed coatings as a function of the initial powder parameters and the type of the thermal spraying procedure.
Unidirectional hexagonal rare-earth disilicide nanowires on vicinal Si(100)-2×1
Rare-earth disilicide nanowires grown on vicinal Si(100) with a miscut of 2–2.5° toward the [110] azimuth at 600 °C were studied by scanning tunneling microscopy and compared with those grown on flat Si(001). In contrast to rare-earth disilicide nanowires grown on flat Si(100) surfaces, the nanowires grow unidirectionally along the [01̄1] direction of the vicinal Si(100) surface. Rare-earth disilicide nanowires form bundles composed of single nanowire units on both flat and vicinal surfaces. Yet, on the vicinal surface, the bundle width is comparable to the width of the terrace. The average nanowire length on the vicinal substrate is longer than that on the flat substrate. Scanning tunneling spectroscopy shows that the rare-earth disilicide nanowires have metallic properties.