Search

Your search keyword '"Sloof W"' showing total 84 results
Start Over Author "Sloof W"
84 results on '"Sloof W"'

67. TOUGHENING OF A ZrC PARTICLE-REINFORCED Ti3AlC2 COMPOSITE.

Author

Song, G. M., Xu, Q., Sloof, W. G., Li, S. B., and Van der Zwaag, S.

Subjects
STRENGTH of materials, TITANIUM carbide, ZIRCONIUM compounds, TRANSMISSION electron microscopy, SCANNING electron microscopy, MICROSTRUCTURE
Abstract

The article focuses on a study which explored the toughening of the Ti3AlC2 ternary carbide with the addition of a ZrC particle. The results of a microstructural analysis with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that during hot pressing the ZrC was partially decomposed, leading to zirconium (Zr) being dissolving into the Ti3AlC2 to form a TiAlC solid solution containing Zr.

Published
2008

68. Microstructural Features of Austenite Formation in C35 and C45 alloys.

Author

Savran, V. I., Van Leeuwen, Y., Hanlon, D. N., Kwakernaak, C., Sloof, W. G., and Sietsma, J.

Subjects
CARBON steel, HEAT treatment of steel, AUSTENITE, ELECTRON probe microanalysis, SCANNING electron microscopy, CEMENTITE, PERLITE, FERRITES
Abstract

The microstructural evolution during continuous heating experiments has been studied for two C-Mn steels with carbon contents in the range 0.35 to 0.45 wt pct using optical microscopy, scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). It is shown that the formation of the austenitic phase is possible in pearlite as well as in ferrite regions. Thus, a considerable overlap in time of ferrite-to-austenite and pearlite-to-austenite transformations is likely to occur. Another observation that was made during the experiments is that, depending on the heating rate, the pearlite-to-austenite transformation can proceed in either one or two steps. At low heating rates (0.05 °C/s), ferrite and cementite plates transform simultaneously. At higher heating rates (20 °C/s), it is a two-step process: first ferrite within pearlite grains transforms to austenite and then the dissolution of the cementite Iamellae takes place. Several types of growth morphologies were observed during the experiments. The formation of a finger-type austenite morphology was noticed only for low and intermediate heating rates (0.05 °C/s and 20 °C/s), but not for the heating rate of 300 °C/s. The formation of this fingertype austenite occurs on pearlite-ferrite grain boundaries and coincides with the direction of cementite plates. The carbon inhomogeneities in the microstructure affect the formation of martensitic/bainitic structures on cooling. [ABSTRACT FROM AUTHOR]

Published
2007
Full Text
View/download PDF

69. Investigation of Cr(III) Based Conversion Coatings On Electrogalvanised Steel.

Author

Zhang, X., van den Bos, C., Sloof, W. G., Terryn, H., Hovestad, A., and de Wit, J. H. W.

Subjects
COATING processes, COATINGS industry, STEEL corrosion, CHROMIUM, BEHAVIOR, HYGIENE
Abstract

The corrosion behaviour of Cr(III) based conversion coatings on electrogalvanised steel was studied using polarisation and electrochemical impedance spectroscopy measurements in 0.01M NaCl solution (pH 6). The Cr(III) based conversion treatments were carried out in two different commercial trivalent chromium baths (pH 1.8–2.0). With an immersion time of 1 min, the thickness of the first type of Cr(III) based coating (blue) was about 94 nm and the thickness of the second type of coating (iridescent yellow) was about 250 nm; these thicknesses were determined by spectroscopic ellipsometry. As a comparison, a Cr(VI) based coating on electrogalvanised steel was also studied. The morphologies and compositions of the coatings were investigated by means of scanning electron microscopy, Fourier transform infrared spectroscopy and Auger electron spectroscopy. The Cr(III) coatings contained mainly a mixture of zinc oxides and chromium oxides/ hydroxides, and no Cr(VI) was detected in these coatings. The polarisation measurements in NaCl solution showed a retarded cathodic reaction for both the Cr(III) cmd the Cr(VI) based coatings. The corrosion resistance of the thicker Cr(III) coating was greater than that of the thinner Cr(III) coating. However, in the cases studied, the Cr(III) coatings stiff did not inhibit the corrosion of the electrogalvanised steel as effectively as did the Cr(VI) based coatings. The reason may be that the Cr(III) coatings do not possess the ‘self-healing’ properties that the Cr(VI) based coatings do. [ABSTRACT FROM AUTHOR]

Published
2004
Full Text
View/download PDF

71. XPS and Mössbauer Characterization of Au/TiO<INF>2</INF> Propene Epoxidation Catalysts

Author

Zwijnenburg, A., Goossens, A., Sloof, W. G., Craje, M. W. J., Kraan, A. M. van der, Jongh, L. Jos de, Makkee, M., and Moulijn, J. A.

Abstract

Gold catalysts supported on TiO2 and TiO2/SiO2 were used in gas-phase propene epoxidation with a hydrogen−oxygen mixture. The catalysts were characterized by 197Au Mössbauer absorption spectroscopy (MAS), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Gold particle sizes of 1 wt % Au catalysts calcined at 673 K ranged from 3 to 6 nm. Two Au contributions were found in Mössbauer spectra and assigned to bulk metallic Au atoms in the core of a gold particle and metallic gold on the outer surface of this particle. By MAS, no evidence for charge transfer from support to Au particle could be found. The Auger parameters confirmed that the surface layer of 3−5 nm gold particles is metallic. Deactivation is not due to a change in the active gold species but is related to the TiO2 support. In the preparation via deposition-precipitation, Au(OH)3 species are converted to metallic gold during calcination. Gold particles do not gradually grow during calcination, possibly due to the simultaneous conversion of Au(OH)3 moieties with dehydroxylation of the TiO2 support. Epoxidation activity increases with the amount of surface metallic gold. No evidence for oxidized gold under reaction conditions was found.

Published
2002
Full Text
View/download PDF

74. Chemical constitution and microstructure of TiCx coatings chemically vapour deposited on Fe-C substrates; effects of iron and chromium

Author

Sloof, W. G., Delhez, R., de Keijser, Th. H., Schalkoord, D., Ramaekers, P. P. J., and Bastin, G. F.

Abstract

TiCx coatings were chemically vapour deposited in an industrial reactor on Fe-C substrates with carbon contents between 0.06 and 1.20 wt % C. Electron probe microanalyses showed that significant amounts of chromium and iron were present in the coatings and that chromium was also present in the substrate region adjacent to the coatings. By comparing calculated and measured lattice parameters (corrected for the internal stresses present) it became evident that the chromium was in solid solution in TiCx, whereas the iron was not. This was confirmed by micro Auger electron spectroscopy and X-ray diffraction phase analyses. The carbon to metal ratio,x, of the TiCx coatings decreased with increasing distance to the coating/substrate interface. The effect of iron on the X-ray diffraction line broadening and hardness of the coatings was large (in contrast with the effect of chromium) and increased with increasing distance to the coating/substrate interface because of a decreasing iron particle size. The TiCx crystallite size was small and constant throughout the thickness of the coatings. The chromium present in the substrate region adjacent to the TiCx coatings influenced the microstructure of the substrate by formation of iron, chromium-carbides and reduced the growth rate of the coatings.

Published
1988
Full Text
View/download PDF

75. Prediction and Measurement of Compressive and Tensile Stresses in Coatings of Tic and Tin Chemically Vapour Deposited on Various Substrates

Author

Sloof, W. G., Rijpkema, H. J. M., Delhez, R., de Keijser, Th. H., and Mittemeijer, E. J.

Abstract

Residual stresses in chemically vapour deposited (CVD) TiC and TiN coatings on various substrates were measured using X-ray diffraction. A quantitative prediction of the vaiue of the strain (and stress) was obtained from the difference in thermal shrinkage between layer and substrate on cooling from the CVD temperature to room temperature. The sign of the strains measured always agreed with the prediction, but in a number of cases the absolute value of the elastic strain measured was smaller than that predicted. For layers on iron and Fe-1.0 wt-%C substrates this difference is caused by strain accommodating processes in the substrate, mainly during phase transformations. For TiN layers on molybdenum and tungsten substrates, strain accommodating processes occur in the layer, and these may originate in the microstructure of the layer.

Published
1987
Full Text
View/download PDF

76. Integrated Criteria Document PAH's

Author

Sloof W, Matthijsen AJCM, Montizaan GK, Ros JPM, van den Berg R, Eerens HC, Goewie CE, Kramers PGN, van de Meent D, Posthumus R, Schokkin GJH, Wegman RCC, Vaessen HAMG, Wammes JIJ, Bral EAMA, Compaan H, Duiser JA, Duyzer JH, Eggels PG, Huldy HJ, van der Most PFJ, Mulders EJ, Rodenburg LJM, Roemer MGM, Schouten A, Thijsse TR, Tielrooy JA, van der Woerd KF, Sloof W, Matthijsen AJCM, Montizaan GK, Ros JPM, van den Berg R, Eerens HC, Goewie CE, Kramers PGN, van de Meent D, Posthumus R, Schokkin GJH, Wegman RCC, Vaessen HAMG, Wammes JIJ, Bral EAMA, Compaan H, Duiser JA, Duyzer JH, Eggels PG, Huldy HJ, van der Most PFJ, Mulders EJ, Rodenburg LJM, Roemer MGM, Schouten A, Thijsse TR, Tielrooy JA, and van der Woerd KF

Abstract

RIVM rapport:Dit rapport bevat een systematisch overzicht en een kritische evaluatie van de belangrijkste gegevens over de prioritaire stofgroep PAK ten behoeve van het effectgericht milieubeleid.

Published
1989

77. Ontwerp-basisdocument benzeen

Author

Sloof W, Bresser AHM, Besemer AC, Blokzijl PJ, Canton JH, van Gemert Lj, Huldy HJ, Huijgen C, Knaap AGAC, Knoop J, Kool HJ, Maas RJM, Minderhoud A, van der Most PFJ, Mulder HCM, van Noort PCM, Ros JPM, Struijs J, Vink GJ, de Vrijer F, van de Wiel HJ, Woutersen RA, Sloof W, Bresser AHM, Besemer AC, Blokzijl PJ, Canton JH, van Gemert Lj, Huldy HJ, Huijgen C, Knaap AGAC, Knoop J, Kool HJ, Maas RJM, Minderhoud A, van der Most PFJ, Mulder HCM, van Noort PCM, Ros JPM, Struijs J, Vink GJ, de Vrijer F, van de Wiel HJ, and Woutersen RA

Abstract

RIVM rapport:Onderhavig document omvat gegevens over benzeen inzake de bronnen en het verspreidingspatroon (bodem, water, lucht, biota), de risico's op basis van afweging van blootstellingsconcentraties en -routes enerzijds en schadelijke concentraties voor mens, (onderdelen van) ecosystemen en materialen anderzijds, en de technische mogelijkheden en economische gevolgen met betrekking tot reductie van deze risico's. Deze informatie dient als wetenschappelijke basis voor het formuleren van het effectgericht normstellingsbeleid.

Published
1986

80. Discrimination between gamma’-Fe4N and epsilon Fe2-3N iron nitride compounds using PCA of Auger electron spectra

Author

Isabelle Vandendael, Oscar Steenhaut, Annick Hubin, Jean Vereecken, Sloof, W. G., Materials and Chemistry, and Metallurgy, Electrochemistry and Materials Science

Subjects
Auger
Abstract

AES offers high spatial resolution that is useful when analysing cross sections of nitrided steels. To discriminate between different iron nitride compounds in such an analysis, so-called factor analysis (FA) can be applied. This requires acquisition of Auger electron spectra which are associated with either the γ′-Fe4N or the ε-Fe2–3N phases as principal components. In this study, the N KLL and Fe LMM Auger electron spectral lines of γ′-Fe4N and ε-Fe2–3N phases were acquired in great detail from the pure γ′-Fe4N and ε-Fe2–3N phases obtained by gaseous nitriding of pure iron. To this end, two different samples of known composition were analysed. Firstly, Auger electron spectra were recorded from a nitrided layer with large γ′-Fe4N grains (∼30 µm) on top of an iron substrate. Secondly, Auger electron spectra were recorded from an ε-Fe2–3N outer layer (∼6 µm) with 26 at.% N, on a γ′-Fe4N layer (∼4 µm) with 20 at.% N, created on top of an iron substrate. The latter sample was also used for FA. It is shown that principal component analysis of a series of N KLL Auger electron spectra recorded from the iron nitride double layer could be represented by three contributions. These principal components are associated with γ′-Fe4N, ε-Fe2–3N and the background. On the other hand, when a background subtraction was applied to the acquired N KLL Auger electron spectra, it was not possible to discriminate between the two iron nitride phases

Catalog

Books, media, physical & digital resources
See catalog results