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Fabienne Delaunois

Bio: Fabienne Delaunois is an academic researcher from University of Mons. The author has contributed to research in topics: Electroless nickel & Coating. The author has an hindex of 19, co-authored 72 publications receiving 1373 citations. Previous affiliations of Fabienne Delaunois include University of Biskra & Faculté polytechnique de Mons.


Papers
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TL;DR: The results of scratch tests show that the Ni-B deposits have good tribological properties under external solicitations as discussed by the authors, they are hard, wear and abrasion resistant, and also have good adhesion to the aluminium substrate.
Abstract: Electroless nickel–boron baths reduced with sodium borohydride can be stabilized with various agents such as thallium nitrate or lead tungstate with no fundamental modification of deposition rates and stability. To improve the mechanical properties of electroless nickel–boron deposits, various heat treatments are applied. At low temperatures, no fundamental changes in the deposit structure are observed, only an improvement of adhesion on aluminium substrate. The values of the Knoop microhardness obtained on these heat-treated deposits are near 600 hk 100 . At higher temperatures, structural changes take place and the nickel–boron deposits crystallize. The microhardness rises until 1050 hk 50 for heat treatments at 350 °C for 4 h. A diffusion layer between the electroless nickel deposit and the aluminium substrate appears at high heat treatment temperatures. The results of scratch tests show that the Ni–B deposits, with or without heat treatments, have good tribological properties under external solicitations. They are hard, wear and abrasion resistant, and also have good adhesion to the aluminium substrate.

178 citations

Journal ArticleDOI
TL;DR: In this paper, the authors examined the possibility of depositing a thick autocatalytic electroless Ni-B plating on aluminium alloys and proposed an alkaline bath containing sodium borohydride as the reducing agent.
Abstract: Light alloys are more and more widely used, notably in aeronautics and the car industry. To improve their superficial properties, they can be covered with a hard and wear resistant protective layer. In this article, we examine the possibility of depositing a thick autocatalytic electroless Ni–B plating on aluminium alloys. We propose an alkaline bath containing sodium borohydride as the reducing agent. The deposition rate is held constant by a regular replenishment of the Ni–B bath allowing a rate of about 25 μm/h. The Knoop microhardness of the Ni–B deposits after the bath reaches about 750 hk100. Appropriate heat treatment can increase the deposit microhardness up to more than 1000 hk100 but must be applied with regard to the substrate properties. The study of these heat treatments will be published in a further paper.

160 citations

01 Jan 2001
TL;DR: In this article, the authors examined the possibility of plating a thick autocatalytic electroless Ni-B deposit on aluminium alloys and proposed an alkaline bath containing sodium borohydride as the reducing agent.
Abstract: Light alloys are more and more widely used notably in aeronautics and the car industry. To improve their superficial properties, they can be covered with a hard and wear resistant protective layer. In this article, we examine the possibility of plating a thick autocatalytic electroless Ni-B deposit on aluminium alloys. We propose an alkaline bath containing sodium borohydride as the reducing agent. The deposition rate is held constant by a regular replenishment of the Ni-B bath allowing a rate of about 25 μm/h. The Knoop microhardness of the Ni-B deposits after the bath reaches about 750 hk 1 0 0 . An appropriate heat treatment can increase the deposit microhardness up to more than 1000 hk 1 0 0 but must be applied in regard to the substrate properties. The study of these heat treatments will be published in a further paper.

141 citations

Journal ArticleDOI
TL;DR: In this article, a comparative hardness study was conducted to assess the influence of load, indent position (free surface or cross section), and heat treatment on the results of the indentation tests.
Abstract: Electroless nickel–boron deposits were synthesized on aluminium alloys and submitted to heat treatments under neutral (95% Ar + 5% H 2 ) atmosphere. Two set of treatment conditions were used: 1 h at 400 °C and 4 h at 180 °C. Micro- and nanohardness measurements were carried out on the free surface of the sample and on polished cross-sections. A comparative hardness study was conducted to assess the influence of load, indent position (free surface or cross section), and heat treatment on the results of the indentation tests. Scratch tests were made on selected coatings to assess their adhesive properties and scratch resistance. Roughness measurements were carried out on the coatings before and after heat treatments. The samples were also investigated by XRD (X-ray Diffraction), SEM (Scanning electron microscopy) and optical microscopy to link their mechanical properties to their composition, structure and morphology.

89 citations

Journal ArticleDOI
TL;DR: In this paper, the structure of electroless nickel-boron with a boron content around 5.5% was investigated in the as deposited and heat treated states by X-ray diffraction and by transmission electron microscopy on thinned cross-sections prepared by focused ion beam technique.
Abstract: The structure of electroless nickel–boron with a boron content around 5 wt.% was investigated in the as deposited and heat treated states by X-ray diffraction and by transmission electron microscopy on thinned cross-sections prepared by focused ion beam technique. In the as-deposited state, the presence of areas with short range order has been observed. This shows that electroless nickel–boron coatings with high boron content are not fully amorphous, as is usually stated. After heat treatment, the structure of electroless nickel–boron appeared constituted of nanocrystalline nickel–boride Ni3B.

84 citations


Cited by
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01 Apr 1988-Nature
TL;DR: In this paper, a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) is presented.
Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

9,929 citations

Journal ArticleDOI
TL;DR: The development of metal deposition processes based on electroless nickel, alloy and composite coatings on various surfaces has witnessed a surge in interest among researchers, with many recent applications made possible from many excellent properties as mentioned in this paper.

680 citations

Journal ArticleDOI
TL;DR: In this article, the authors reviewed the tribological advancement of different electroless nickel coatings based on the bath types, structure and also the tribo testing parameters in recent years.

477 citations

Journal ArticleDOI
TL;DR: In this paper, the performance of metal oxide thin film electrodes on activated carbon has been evaluated in the context of supercapacitors, showing that metal oxide films will play a major role in super-capacitor technology and are expected to significantly develop the capabilities of these devices in the near future.
Abstract: The electrochemical capacitor (EC), also called as supercapacitor, is an energy storage device possessing a unlimited life-cycle and high power density known to store energy in the double-layer or through supercapacitance as a result of an applied potential. Fundamental values in relation to the major chemical and physical qualities of electrode materials are explained in the following review, with carbon-made electrodes, specially activated carbon highlighted in regards to their improvement of the typical power and energy densities of ECs. Supercapacitive materials, remarkably transition metal oxides are revealed by the potential to further develop EC performance through synergistic effects and asymmetric design. Recently, several chemically deposited metal oxide thin film electrodes as well as ruthenium oxide, manganese oxide, cobalt oxide, nickel oxide, iron oxide, ferrites etc., have been evaluated in supercapacitors. This review presents supercapacitor performance data of metal oxide thin film electrodes on activated carbon offered by electroless plating as a suitable, fast and economical technique. The supercapacitors demonstrated the specific capacitance (Sc) principles, which are relatively comparable with bulk electrode values; therefore, it is likely that metal oxide films will continue to play a major role in supercapacitor technology and are expected to significantly develop the capabilities of these devices in the near future.

297 citations