Flanders Materials Center

Gent, Belgium

Flanders Materials Center

Gent, Belgium
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Verhiest K.,ArcelorMittal | Verhiest K.,Belgian Nuclear Research Center | Verhiest K.,Ghent University | Mullens S.,Flemish Institute for Technological Research | And 6 more authors.
Ceramics International | Year: 2014

High-temperature contact angle experiments of liquid iron-chromium (Fe-Cr) drops onto ceramic yttria (Y2O3) substrates were carried out in order to investigate the wetting behavior of Y2O3 nano-particles in contact with an iron melt containing elemental Cr. Therefore, the correlation between the wetting behavior of the iron drop in contact with Y2O3 was studied for drops with variable Cr-content and for different powder grades. The wetting behavior of liquid binary Fe-Cr alloys in contact with the Y2O3 ceramic substrates at high temperature, was investigated using the static sessile drop method. The contact angle formed at the interaction interface was evaluated using static drop imaging and quantified using the method proposed by Bartlett and Hall [10]. Our experiments demonstrate that the wetting behavior of binary Fe-Cr alloys drops in contact with Y2O3 ceramics compared to other oxides such as Al2O3, is quite weak. Only for the test condition of pure electrolytic iron, i.e., without Cr addition, the contact angles ( θc) were found to approach 90 or lower in all cases. Furthermore, a 9 wt% Fe-Cr alloy with silicon addition seems to improve the wetting behavior of liquid Fe-Cr drops in contact with Y2O 3. Moreover, variation in powder purity seems to be of crucial importance. © 2013 Elsevier Ltd and Techna Group S.r.l.


Verhiest K.,ArcelorMittal | Verhiest K.,Belgian Nuclear Research Center | Verhiest K.,Ghent University | Mullens S.,Flemish Institute for Technological Research | And 6 more authors.
Ceramics International | Year: 2014

Oxide dispersion strengthened (ODS) steels are considered as the future structural material of interest for nuclear power plants, due to their elevated creep resistance at higher operation temperatures. In this study, a 0.3 wt% nano-yttria (Y2O3) dispersed iron cast trial was elaborated using rapid solidification processing (RSP). The nano-sized Y 2O3 particles were introduced into the iron matrix using the formulation of a low-concentrated colloidal dispersion. The aim of this study is to understand the dispersibility behaviour of the ceramic Y 2O3 nano-powder when added to an iron melt as a colloidal dispersion, during high-temperature melting or RSP. It was found, after casting the iron/Y2O3 composites, that apart from an inhomogeneous dispersion, super-micron agglomerates alternate dispersed zones. Overall, this study tried to assay the casting practice of iron/Y2O3 composites using RSP. As an overall conclusion, it can be stated that wettability in synergy with porous materials characteristics, (especially powder purity) seems to have a significant impact on the dispersibility of Y 2O3 particles and its super-micron sphere formation behavior in an iron melt. © 2014 Elsevier Ltd and Techna Group S.r.l.


Pescarmona P.P.,Catholic University of Leuven | Janssen K.P.F.,Catholic University of Leuven | Stroobants C.,Catholic University of Leuven | Molle B.,Flanders Materials Center | And 3 more authors.
Topics in Catalysis | Year: 2010

The conversion of dihydroxyacetone to ethyl lactate catalysed by different solid acids was investigated by means of High-Throughput Experimentation. A mesoporous amorphous aluminosilicate catalyst displaying very high selectivity and a good yield towards the lactate was identified. The correlation between the type of acid sites and the catalytic behaviour is discussed. © 2009 Springer Science+Business Media, LLC.


Pescarmona P.P.,Catholic University of Leuven | Janssen K.P.F.,Catholic University of Leuven | Delaet C.,Groep T Leuven Engineering College Associated With Ku Leuven | Stroobants C.,Catholic University of Leuven | And 6 more authors.
Green Chemistry | Year: 2010

The direct conversion of C3 sugars (or trioses) to alkyl lactates was achieved using zeolite catalysts. This reaction represents a key step towards the efficient conversion of bio-glycerol or formaldehyde to added-value chemicals such as lactate derivatives. The highest yields and selectivities towards the desired lactate product were obtained with Ultrastable zeolite Y materials having a low Si/Al ratio and a high content of extra-framework aluminium. Correlating the types and amounts of acid sites present in the different zeolites reveals that two acid functions are required to achieve excellent catalysis. Brønsted acid sites catalyse the conversion of trioses to the reaction intermediate pyruvic aldehyde, while Lewis acid sites further assist in the intramolecular rearrangement of the aldehyde into the desired lactate ester product. The presence of strong zeolitic Brønsted acid sites should be avoided as much as possible, since they convert the intermediate pyruvic aldehyde into alkyl acetals instead of lactate esters. A tentative mechanism for the acid catalysis is proposed based on reference reactions and isotopically labelled experiments. Reusability of the USY catalyst is demonstrated for the title reaction. © 2010 The Royal Society of Chemistry.

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