I. Garcia

Bio: I. Garcia is an academic researcher from Katholieke Universiteit Leuven. The author has contributed to research in topics: Composite number & Particle size. The author has an hindex of 4, co-authored 4 publications receiving 579 citations. Previous affiliations of I. Garcia include Spanish National Research Council.

Electrodeposition and sliding wear resistance of nickel composite coatings containing micron and submicron SiC particles

Abstract: SiC particles of three different sizes, namely 5, 0.7 and 0.3 μm, were codeposited with nickel from Watts’ solutions. It was found that for a given number density of particles in the plating solution, the number density of particles in the coating increases with decreasing particle size. The friction and wear behavior of these composite coatings was evaluated in uni- and bi-directional sliding tests against corundum balls. The best sliding wear resistance was obtained with Ni–SiC composite coatings containing 4–5 vol.% submicron SiC particles.

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.

Corrosion-wear of passivating materials in sliding contacts based on a concept of active wear track area

Abstract: The concept of active wear track area is proposed as a way to investigate the mechanism of the corrosion-wear behavior of passive materials under sliding conditions. This active wear track area represents that part of the wear track that looses temporarily its passive character due to the mechanical interaction during sliding. It is shown that the active wear track area can be determined from repassivation kinetics measured on electrochemically activated material by a potential pulse method, and from anodic currents measured during sliding ball-on-disk tests. The use of that concept is illustrated for the case of stainless steel AISI 316 immersed in a 0.5 M H2SO4 solution. At loads below 2 N, no breakthrough of the oxide film is noticed. At loads between 2 and 12 N, the corrosion-wear agrees well with Quinn’s mild oxidation wear mechanism. The corrosion-wear of AISI 316 consists then of two processes namely a mechanical delamination of the passive layer in part of the wear track, followed by a progressive electrochemical re-passivation of that active wear track area. The thickness of the passive layer on AISI 316 was derived from the active wear track area and the electrochemical response of passive and active AISI 316 material. A value of 2–3 nm was obtained that agrees well with data obtained by other methods. Above a load of 12 N, the corrosion-wear increases steeply due to a degradation process involving abrasion and/or breakdown of more than just the oxide film. © 2001 Elsevier Science B.V. All rights reserved.

A mild oxidation model valid for discontinuous contacts in sliding wear tests: role of contact frequency

Abstract: The volumetric wear rate of PVD TiN-coated disks sliding against corundum balls has been investigated as a function of wear track diameter (16–50 mm), sliding speed (0.06–1.41 m/s) and contact frequency (1–16 Hz) in uni-directional ball-on-disk sliding wear tests. The wear rate of the disk material is shown to depend not only on the usual test parameters, namely sliding speed and contact load, but also on the contact frequency. In order to take this last parameter into account, a modification to Quinn’s mild oxidation wear model originally developed for the continuous contact of a pin against a disk, is proposed to account for discontinuous sliding contacts. As a result, a low dispersion in the wear test results is obtained in contrast with disk wear data from pin-on-disk and ball-on-disk tests reported in the literature. By including contact frequency in addition to load and speed, as an independent factor, modeling of the mild oxidation wear of materials in discontinuous sliding contacts has been achieved.

Recent progress in the development and properties of novel metal matrix nanocomposites reinforced with carbon nanotubes and graphene nanosheets

Abstract: One-dimensional carbon nanotubes and two-dimensional graphene nanosheets with unique electrical, mechanical and thermal properties are attractive reinforcements for fabricating light weight, high strength and high performance metal-matrix composites. Rapid advances of nanotechnology in recent years enable the development of advanced metal matrix nanocomposites for structural engineering and functional device applications. This review focuses on the recent development in the synthesis, property characterization and application of aluminum, magnesium, and transition metal-based composites reinforced with carbon nanotubes and graphene nanosheets. These include processing strategies of carbonaceous nanomaterials and their composites, mechanical and tribological responses, corrosion, electrical and thermal properties as well as hydrogen storage and electrocatalytic behaviors. The effects of nanomaterial dispersion in the metal matrix and the formation of interfacial precipitates on these properties are also addressed. Particular attention is paid to the fundamentals and the structure–property relationships of such novel nanocomposites.

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.

Electrochemical techniques for studying tribocorrosion processes

Abstract: The combined corrosion-wear degradation of materials in sliding contacts immersed in electrically conductive solutions can be investigated in situ by electrochemical techniques. Such techniques are the open circuit potential measurements, the potentiodynamic polarization measurements, and the electrochemical impedance measurements. In this paper, capabilities and present limitations of these techniques are discussed based on a tribocorrosion study of a AISI 316 stainless steel and an iron-nickel alloy immersed in aerated 0.5 M sulfuric acid and sliding against a corundum counterpart. Some novel insights into the tribocorrosion mechanism gathered in this way are discussed.

Mechanical properties and wear and corrosion resistance of electrodeposited Ni-Co/SiC nanocomposite coating

Abstract: Ni–Co/SiC nanocomposite coatings with various contents of SiC nano-particulates were prepared by electrodeposition in a Ni–Co plating bath containing SiC nano-particulates to be co-deposited. The influences of the nanoparticulates concentration, current density, stirring rate and temperature of the plating bath on the composition of the coatings were investigated. The shape and size of the SiC nano-particulates were observed and determined using a transmission electron microscope. The polarization behavior of the composite plating bath was examined on a PAR-273A potentiostat/galvanostat device. The wear behavior of the Ni–Co/SiC nanocomposite coatings was evaluated on a ball-on-disk UMT-2MT test rig. The worn surface morphologies of the Ni–Co/SiC nanocomposite coatings were observed using a scanning electron microscope. The corrosion behavior of the nanocomposite coatings was evaluated by charting the Tafel curves of the solution of 0.5 mol L −1 NaCl at room temperature. It was found that the cathodic polarization potential of the composite electrolyte increased with increasing SiC concentration in the plating bath. The microhardness and wear and corrosion resistance of the nanocomposite coatings also increased with increasing content of the nano-SiC in the plating bath, and the morphologies of the nanocomposite coatings varied with varying SiC concentration in the plating bath as well. Moreover, the co-deposited SiC nano-particulates were uniformly distributed in the Ni–Co matrix and contributed to greatly increase the microhardness and wear resistance of the Ni–Co alloy coating.

Fabrication of multi-layer SU-8 microstructures

Abstract: The fabrication of multi-level SU-8 microstructures using multiple coating and exposure steps and a single developing step has been achieved for up to six layers of SU-8. Alternating layers of SU-8 2010 (thin) and SU-8 2100 (thick) photoresist films were spin coated, followed by soft-bake, ultraviolet (UV) exposure and post-exposure bake steps. The multiple SU-8 layers were simultaneously developed to create patterned microstructures with overall thicknesses of up to 500 µm and minimum lateral feature size of 10 µm. The use of a single developing step facilitated fabrication of complex multi-level SU-8 microstructures that might be difficult, or even impossible, to achieve by sequential processing of multiple SU-8 layers that are individually coated, baked, exposed and developed.