Gijsbertus Langelaan

Bio: Gijsbertus Langelaan is an academic researcher from Katholieke Universiteit Leuven. The author has contributed to research in topics: Corrosion & Pitting corrosion. The author has an hindex of 1, co-authored 3 publications receiving 153 citations.

Improved corrosion resistance through microstructural modifications induced by codepositing SiC-particles with electrolytic nickel

Abstract: Micron and submicron-sized SiC-particles (5 and 0.3 μm respectively) were codeposited with nickel from a Watts electrolyte. The Ni–SiC composite coatings showed a better corrosion resistance in a 0.6 M NaCl solution than nickel electrodeposited under the same conditions. The corrosion rate of Ni–SiC decreases by two orders of magnitude with respect to pure Ni coatings. This improved corrosion resistance is quite independent of the size and amount of embedded particles, except for the smallest SiC-particles investigated. In that case, the pitting corrosion potential shifts to more noble values indicating a notable reduction of the localized corrosion susceptibility. This improved corrosion resistance of Ni–SiC coatings containing submicrometric SiC-particles is linked to a change in grain morphology and texture of the coatings. That morphology evolves from columnar grains to small and equiaxed grains.

Determination of the morphological textures of fibres in a composite material made from a textile of AISI 316L fibres

Abstract: The orientation distribution (morphological texture) of fibres in a composite is very important in determining the properties of the material. Therefore, methods which can provide quantitative descriptions of the morphological texture are essential. One approach to determining the morphological texture function (MTF) is to measure the orientation distribution of the crystals in the fibres. Since many types of fibres used for reinforcements are crystalline and textured (i.e. carbon fibres, steel fibres, etc.) this approach may be interesting for commercial/industrial applications. For this technique to be applied, the crystallographic texture intrinsic to the fibres must be determined and subsequently, measurements of the 'global' crystallographic texture should be made in the composite. The morphological texture can then be calculated by a deconvolution of the composite texture with the fibre's crystallographic texture. The deconvolution is most easily performed using the series expansion representation of texture functions. In this paper, the morphological texture was determined in a woven fabric made from bundle drawn AISI 316L stainless steel fibres embedded in an Al-13wt% Si alloy matrix. Straight fibres removed from the fabric serve as the reference material for the deconvolution. Neutron diffraction pole figures were used to determine the MTF's.

Determination of Morphological Textures of the Fibres in Composite Materials Made from Textiles of Carbon Fibres

Abstract: The orientation distribution of fibres (morphological texture) in a composite is very important in determining the properties of the material. Therefore, methods which can provide quantitative descriptions of the morphological texture are essential. One approach to determining the morphological texture function (MTF) is to measure the orientation distribution of the crystals in the fibres. Since many types of reinforcing fibres are crystalline and textured (i.e. carbon fibres, whiskers, etc.) this approach may be interesting for commercial/industrial applications. For this technique to be applied, the crystallographic texture intrinsic to the fibres must be determined and subsequently measurements of the crystallographic texture should be made in the composite. The morphological texture can then be calculated by a deconvolution of the composite texture with the fibre’s intrinsic texture. In this paper, morphological textures are determined in woven fabrics made from carbon fibres embedded in a polymer matrix. Straight fibres removed from the fabric serve as the reference material for the deconvolution. It is demonstrated that this technique is applicable and can resolve the orientation distribution to an accuracy greater than is needed for determining the elastic properties.

Electrodeposition of Ni–SiC nano-composite coatings and evaluation of wear and corrosion resistance and electroplating characteristics

Abstract: Ni–SiC nano-composite coatings with different contents of SiC nano-particulates were prepared by means of the conventional electrodeposition in a nickel-plating bath containing SiC nano-particulates to be co-deposited. The dependence of SiC nano-particulates amount in the nano-composite coatings was investigated in relation to the SiC concentration in bath, cathode current density, stir rate and temperature of plating bath and it is shown that these parameters strongly affected the volume percentage of SiC nano-particulates. The deposition efficiency with and without SiC nano-particulate in bath was studied. The morphology and phases of the electrodeposited nano-composite were studied. The wear behavior of the nano-composite coatings was evaluated on a ball-on-disk test. The corrosion behavior of the nano-composite coatings was evaluated in the solution of 0.5 M NaCl at room temperature. It was found that the cathodic polarization potential increased with increasing the SiC concentration in the bath. The microhardness and wear and corrosion resistance of the nano-composite coatings also increased with increasing content of the SiC nano-particulate in bath. The SiC distribution in the nano-composite coatings at low concentrations of SiC in bath was uniform across the coatings, but at high concentrations, SiC nano-particulates on the surface were agglomerated.

Composite Ni/Al2O3 coatings and their corrosion resistance

Abstract: Composite coatings Ni/Al2O3 were electrochemically deposited from a Watts bath. Al2O3 powder with particle diameter below 1 μm was codeposited with the metal. The obtained Ni/Al2O3 coatings contained 5–6% by weight of corundum. The structure of the coatings was examined by scanning electron microscopy (SEM). It has been found that the codeposition of Al2O3 particles with nickel disturbs the nickel coating's regular surface structure, increasing its microcrystallinity and surface roughness. DC and AC electrochemical tests were carried out on such coatings in a 0.5 M solution of Na2SO4 in order to evaluate their corrosion resistance. The potentiodynamic tests showed that the corrosion resistance of composite coating Ni/Al2O3 is better than that of the standard nickel coating. After 14 days of exposure the nickel coating corrodes three times faster than the Ni/Al2O3 coating. The electrochemical behaviour of the coatings in the corrosive solution was investigated by electrochemical impedance spectroscopy (EIS). An equivalent circuit diagram consisting of two RC electric circuits: one for electrode, nickel corrosion processes and the other for processes causing coating surface blockage, were adopted for the analysis of the impedance spectra. The changes in the charge transfer resistance determined from the impedance measurements are comparable with the changes in corrosion resistance determined from potentiodynamic measurements.

Hardening effect induced by incorporation of SiC particles in nickel electrodeposits

Abstract: Pure Ni and nickel matrix composite electrocoatings containing micron- and nano-SiC particles (1 μm and 20 nm respectively) were produced under direct and pulse current conditions from an additive-free Watts type bath. The effect of the particle size, codeposition percentage of SiC and type of imposed current on the microhardness as well as on the microstructure of the electrodeposits were investigated. Ni/SiC composite deposits prepared under either direct or pulse current conditions exhibited a considerable strengthening effect with respect to pure Ni coatings. The improved hardness of composite coatings was associated to specific structural modifications of Ni crystallites provoked by the adsorption of H+ on the surface of SiC particles, thus leading to a (211) texture mode of Ni crystal growth. Pulse electrodeposition significantly improved the hardness of the Ni/SiC composite coatings, especially at low duty cycles, in which grain refinement and higher SiC incorporation (vol. %) was achieved. The enhanced hardness of Ni/nano-SiC deposits, as compared to Ni/micron-SiC composites, was attributed to the increasing values of the number density of embedded SiC particles in the nickel matrix with decreasing particle size. In addition, the observed hardening effects of the SiC particles might be associated to the different embedding mechanisms of the particles, which could be characterized as inter-crystalline for micron-SiC and partially intra-crystalline for nano-SiC particles.

Effect of pulse electrodeposition parameters on the properties of Ni/nano-SiC composites

Abstract: Pure nickel and nickel matrix composite deposits containing nano-SiC particles were produced under both direct and pulse current conditions from an additive-free nickel Watts’ type bath. It has been proved that composite electrodeposits prepared under pulse plating conditions exhibited higher incorporation percentages than those obtained under direct plating conditions, especially at low duty cycles. The study of the textural perfection of the deposits revealed that the presence of nano-particles led to the worsening of the quality of the observed [1 0 0] preferred orientation. Composites with high concentration of embedded particles exhibited a mixed crystal orientation through [1 0 0] and [2 1 1] axes. The embedding SiC nano-particles in the metallic matrix by an intra-crystalline mechanism resulted in the production of composite deposits with smaller crystallite sizes and more structural defects than those of pure Ni deposits. A dispersion-hardening effect was revealed for composite coatings independently from applied current conditions. Pulse electrodeposition significantly improved the hardness of the Ni/SiC composite deposits, mainly at low duty cycle and frequency of imposed current pulses.