Brussels, Belgium
Brussels, Belgium
Time filter
Source Type

Hashemi N.,University of Liège | Mertens A.,University of Liège | Montrieux H.-M.,University of Liège | Tchuindjang J.T.,University of Liège | And 3 more authors.
Surface and Coatings Technology | Year: 2017

The oxidative wear behaviour of four different High Speed Steel (HSS) thick coatings (one cast material and three laser clad deposits with varying Mo, V and W contents) was investigated using a pin-on-disc tribometer at two different sliding speeds of 10 cm/s and 50 cm/s. Microstructural characterization (before and after the wear tests) was carried out by SEM and wear debris was analysed by XRD. For all four materials, the oxide layer was formed of hard and brittle haematite-type α-Fe2O3, prone to break and release debris that acted as a third body, thus increasing sample wear. The laser clad HSS materials exhibited a higher wear resistance than their conventional cast counterpart, thanks to their finer microstructures. In particular, the coarser MC and M2C carbides present in the cast material were sensitive to cracking during the wear tests, releasing debris that contributed to increased third body abrasion together with oxide fragments. A detailed comparison of the wear behaviour of the three laser clad deposits, in correlation with their different microstructures, further demonstrated that harder V-rich MC carbides offered better wear resistance compared to the softer W-rich M2C carbides. The morphology of the carbides also played a role in determining the wear resistance at the higher sliding speed of 50 cm/s. Clover-shaped primary MC carbides resisted wear better than angular ones due to their better geometric anchoring. Similarly, the geometric anchoring of eutectic M2C carbides, forming a quasi-continuous network at the grain boundaries of the matrix, proved beneficial at higher sliding speed. © 2017 Elsevier B.V.

Rahier A.H.,Belgian Nuclear Research Center | Lunardi S.,Belgian Nuclear Research Center | Nicolle F.,National Graduate School of Chemistry, Rennes | George S.M.,Sirris
Talanta | Year: 2010

The sensitive differential pulse anodic stripping voltammetry (DPASV) proposed originally by Ishiyama et al. (2001) has been revised and improved to allow the accurate measurement of silicon on a hanging mercury drop electrode (HMDE) instead of a glassy carbon electrode. We assessed the rate of formation of the partially reduced β-silicododecamolybdate and found that metallic mercury promotes the reaction in the presence of a large concentration of Fe3+. The scope of the method has been broadened by carrying out the measurements in the presence of a constant amount of Fe3+. The limit of detection (LOD) of the method described in the present paper is 100 μg Si g-1 of steel, with a relative precision ranging from 5% to 12%. It can be further enhanced to 700 ng Si g-1 of steel provided the weight of the sample, the dilution factors, the duration of the electrolysis and the ballast of iron are adequately revised. The tolerance to several interfering species has been examined, especially regarding Al3+, Cr3+ and Cr VI species. The method was validated using four low-alloy ferritic steels certified by the National Institute of Standards and Technology (NIST). Its application to nickel base alloys as well as to less complicated matrixes is straightforward. It has also been successfully applied to the determination of free silicon into silicon carbide nano-powder. © 2010 Elsevier B.V.

Bouquet J.,Catholic University of Leuven | Van Camp D.,Catholic University of Leuven | Malek O.,Sirris | Ten Haaf P.,Sirris | And 2 more authors.
Procedia CIRP | Year: 2016

The growing use of fiber reinforced plastics in injection molding greatly reduces the lifetime of components in dies and molds. In this research, injection nozzles are machined within one set-up, combining machining and selective laser hardening operation. This allows the machining and hardening of die and mold components in one single setup. A thermal model is developed and experimentally validated in order to be able to select optimal hardening parameters and strategy. Hardness values exceeding conventional hardening techniques on tool steel are presented, aiming for a prolonged lifetime of dies and molds. © 2016 The Authors.

Verlee B.,Sirris | Dormal T.,Sirris | Lecomte-Beckers J.,University of Liège
Powder Metallurgy | Year: 2012

Additive manufacturing (AM) techniques offer the possibility to build complex geometries with integrated functionalities. Three-dimensional (3D) printing of metallic powder is probably the only AM technique that can build controlled porosity sintered parts, such as filter elements and fluid permeable components. Many building and sintering parameters can be set to adjust porous properties of the final part. The effects of particle size, particle shape, sintering temperature and sintering time on the final properties of the sintered parts have been analysed. Correlations have been established between these properties and process parameters. © 2012 Institute of Materials, Minerals and Mining.

Kinet D.,University of Mons | Garray D.,Sirris | Megret P.,University of Mons | Caucheteur C.,University of Mons
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

Fibre Bragg gratings (FBGs) are strain sensors that can be embedded into composite materials, without affecting their mechanical performances. In this study, we report the use of a short and weakly tilted FBG inscribed in a single mode highly germanium doped photosensitive optical fibre to discriminate, with a good spatial resolution, strain and temperature effects for structural health monitoring (SHM) application. The transmission spectrum of a weakly tilted FBG (TFBG) presents three regions of interest: the Bragg resonance, the ghost mode resonance and all other cladding mode resonances that are not exploited in this work. We make use of the differential temperature sensitivity of the Bragg mode and the ghost mode to discriminate between temperature and strain effects inside composite materials. © 2013 SPIE.

Morisset C.-E.,University of British Columbia | Morisset C.-E.,Golder Associates | Scoates J.S.,University of British Columbia | Weis D.,University of British Columbia | Rahier A.,Sirris
Geostandards and Geoanalytical Research | Year: 2014

The high abundances of the high field-strength elements in ilmenite and rutile make these minerals particularly suitable for hafnium isotopic investigations. We present a technique for separating Hf by ion exchange chemistry from high-TiO2 (> 40% m/m) minerals to achieve precise Hf isotopic composition analyses by MC (multiple collector)-ICP-MS. Following digestion and conversion to chlorides, the first elution column is used to separate iron and the rare earth elements, the second column is designed to separate most of the titanium from Hf, an evaporation step using HClO4 is then performed to remove any trace of HF in preparation for the third column, which is needed to eliminate any remaining trace of titanium. The modified chemistry helped to improve the yields from < 10 to > 78% as well as the analytical precision of the processed samples (e.g., sample 2033-A1, 176Hf/177Hf = 0.282251 ± 25 before vs. 0.282225 ± 6 after). The technique was tested on a case study in which the Hf isotopic ratios of ilmenite and rutile (analysed prior to the chemistry improvement) were determined and permitted to evaluate that the origin of rutile-bearing ilmenite deposits is from the same or similar magma than their, respectively, associated Proterozoic anorthosite massifs (Saint-Urbain and Lac Allard) of the Grenville Province in Québec, Canada. © 2013 The Authors. Geostandards and Geoanalytical Research © 2013 International Association of Geoanalysts.

Mampaey F.,Sirris | Habets D.,Heraeus Holding GmbH | Plessers J.,Heraeus Holding GmbH | Seutens F.,Heraeus Holding GmbH
International Journal of Metalcasting | Year: 2010

Lately, the present authors published a study where oxygen activities were measured using a commercial sensor, which became recently available. In ductile cast iron melts with ferritic and pearlitic structure, optimal properties occur for a well-defined oxygen activity. Castings poured in these circumstances present maximal nodularity, elongation and ferrite content combined with lowest hardness. Additionally, the first results for compacted graphite cast iron were published. The present contribution examines in much more detail the effect of sulfur and oxygen activity on several phenomena important during production of compacted graphite cast iron. These phenomena are the limit for which mechanical properties as defined in ISO16112 are met, the transition from compacted graphite to lamellar graphite and the point at which 20 percent nodularity occurs. Taking into account that the oxygen activity measurement is obtained in about 12 seconds, the sensor seems to be very promising for compacted iron process control. Copyright © 2010 American Foundry Society.

Gonzalez-Deleito N.,Sirris | Tsiporkova E.,Sirris
IEEE International Conference on Industrial Informatics (INDIN) | Year: 2013

In this paper we present Emergencia, a software tool prototype to support the coordinator of an emergency (e.g. at a large industrial site) in the process of taking the appropriate decisions to solve the emergency situation with minimal impact on safety and devastation. Such a coordinator usually performs this task with the help of an emergency plan, a printed document describing relevant procedures to follow during an emergency. Emergency plans of large sites can easily contain hundreds of pages and might be difficult to use when decisions need to be taken quickly. Instead of browsing such a document in search for the relevant procedures, Emergencia guides the coordinator through this document and pro-actively suggests appropriate procedures to follow and pertinent decisions and measures to take, by considering the current status of the emergency situation. © 2013 IEEE.

Guo Y.,Catholic University of Leuven | Loenders J.,Sirris | Duflou J.,Catholic University of Leuven | Lauwers B.,Catholic University of Leuven
Procedia CIRP | Year: 2012

Energy reduction in industry has become one of the main objectives for achieving environment friendly manufacturing. In practice, optimization of energy consumption should be implemented while taking into consideration other parameters such as the obtained surface quality. In this paper, an approach which incorporates both energy consumption and surface roughness is presented for optimizing the cutting parameters in finish turning. Based on a new energy model and a surface roughness model, derived for a given machine tool, cutting parameters are optimized to accomplish a precise surface finish with minimum energy consumption. © 2012 The Authors.

Tsiporkova E.,Sirris | Boeva V.,Technical University of Sofia | Kostadinova E.,Technical University of Sofia
Belgian/Netherlands Artificial Intelligence Conference | Year: 2011

In contrast to conventional clustering algorithms, where a single data set is used to produce a clustering solution, we introduce herein a MapReduce approach for clustering of data sets generated in multipleexperiment settings. It is inspired by the map-reduce functions commonly used in functional programming and consists of two distinctive phases. Initially, the selected clustering algorithm is applied (mapped) to each experiment, separately. This produces a list of different clustering solutions, one for each experiment. These are further transformed (reduced) by portioning the cluster centers into a single clustering solution. The obtained partition is not disjoint in terms of the different participating objects and it is further analyzed and refined by applying Formal Concept Analysis.

Loading Sirris collaborators
Loading Sirris collaborators