Graphene–nickel composites

Pulsed electrodeposition and mechanical properties of Ni-W/SiC nano-composite coatings

Incorporation of nanofillers into the organic coatings might enhance their barrier performance, by decreasing the porosity and zigzagging the diffusion path for deleterious species. Thus, the coatings containing nanofillers are expected to have significant barrier properties for corrosion protection and reduce the trend for the coating to blister or delaminate. On the other hand, high hardness could be obtained for metallic coatings by producing the hard nanocrystalline phases within a metallic matrix. This article presents a review on recent development of nanocomposite coatings, providing an overview of nanocomposite coatings in various aspects dealing with the classification, preparative method, the nanocomposite coating properties, and characterization methods. It covers potential applications in areas such as the anticorrosion, antiwear, superhydrophobic area, self-cleaning, antifouling/antibacterial area, and electronics. Finally, conclusion and future trends will be also reported.

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Nanocomposite Coatings: Preparation, Characterization, Properties, and Applications

Graphene (Gr) nanosheets with multilayer structures were dispersed in a nickel (Ni) plating solution by using a surfactant with a magnetic stirring method. Gr nanosheets were incorporated into a Ni matrix through a plating process to form Ni-Gr composites on a target substrate. Gr nanosheets were uniformly dispersed in the Ni matrix, and the oxygen radicals present in the Gr were reduced during the electro-deposition process. The incorporation of Gr in the Ni matrix increases both the inter-planar spacing and the degree of preferred orientation of crystalline Ni. With the addition of Gr content as low as 0.05 g L−1, the elastic modulus and hardness of the Ni-Gr composites reach 240 GPa and 4.6 GPa, respectively, which are about 1.7 and 1.2 times that of the pure Ni deposited under the same condition. The enhancement in mechanical properties of the composites is attributed to the preferred formation of the Ni crystalline phases in its (111) plane, the high interaction between Ni and Gr and the prevention of the dislocation sliding in the Ni matrix by the Gr. The results suggest that the method of using Gr directly instead of graphene oxide (GO) is efficient and scalable.

https://iopscience.iop.org/article/10.1088/0957-4484/26/6/065706/pdf

Mechanical properties of nickel-graphene composites synthesized by electrochemical deposition.

Due to economical demands to further increase the efficiency of production processes, it is essential to exploit the full potential of wear resistant hard coatings. This is, however, possible only if the coating microstructure and properties are well characterized. Thus, in the present work, recently suggested advanced characterization techniques for coatings are reviewed. The application of atom probe tomography, electron backscatter diffraction and synchrotron X-ray nanodiffraction enables previously unrevealed insights in their chemical composition, microstructure and crystallographic structure. For the determination of mechanical and tribological properties at elevated temperatures, high-temperature nanoindentation and high-temperature ball-on-disk tests in combination with in-situ measurement techniques are discussed. Utilization of micromechanical tests for coatings provides information about their fracture toughness and rupture strength. High-temperature X-ray diffraction and biaxial stress temperature measurements for the determination of the coefficient of thermal expansion are compared. The thermal conductivity as well as the specific heat capacity of coatings can be studied using the 3- ω technique, time domain thermoreflectance and differential scanning calorimetry. The introduced portfolio of characterization techniques enables the determination of a complementary microstructural, mechanical and thermo-physical fingerprint of wear resistant hard coatings, which allows to understand the complex structure–property relations in these materials and subsequently to further improve their performance.

Advanced characterization methods for wear resistant hard coatings: A review on recent progress

Effects of pulse electrodeposition parameters on the properties of Ni–TiO2 nanocomposite coatings

Synthesis of functionally graded nano Al2O3–Ni composite coating by pulse electrodeposition

The main goal of this research was the characterization of the microstructure and texture of functionally graded nickel-Al2O3 nano composite coating. This coating was produced by changing the duty cycle under ultrasonic agitation during pulse deposition process. All of the electrodeposited layers were prepared at 20 A.dm− 2 peak current density and constant frequency of 10 Hz, and the duty cycle has been changed from 90% at the first layer to 10% at the fifth layer. According to SEM images and EBSD results, all layers except the last one showed a truncated pyramidal structure which is a typical morphology for Ni deposited coatings with [100] preferred texture. The last layer which was prepared at duty cycle of 10% exhibited a cauliflower (or colony) structure with small grains that probably resulted in random texture in this layer. EDS results showed more alumina particles can be incorporated at lower duty cycles. Foreign ions incorporation during the deposition process could be the reason for a change of [100] fiber texture to almost random orientation of grains. This rather high incorporation is due to either lower current density or higher OFF-Time duration at low duty cycles in pulse plating process.

Characterization of the microstructure and texture of functionally graded nickel-Al2O3 nano composite coating produced by pulse deposition

Effects of pore-crack relative location on crack propagation in porous media using XFEM method

Nickel-titania composite coatings were prepared under direct current conditions by codeposition of nano titania particles (21 nm) and nickel from a nickel Watts type bath. Current density, concentration of titania particles, effect of agitation, and ultrasonic waves were investigated and the optimum values of these parameters for reaching to maximum vol% of titania particles in the coating were determined. Microhardness of these coatings was investigated by Vickers method and their morphological properties and chemical composition were studied by SEM and EDS analysis, respectively. The results showed that optimal values of current density, concentration of particles, and agitation rate exist that maximum percent of particles codeposited in the coating. Also it is demonstrated that using the ultrasonic waves dramatically decrease the agglomeration of particles in the coating.

S. A. Lajevardi

Papers

Effects of pulse electrodeposition parameters on the properties of Ni–TiO2 nanocomposite coatings

Synthesis of functionally graded nano Al2O3–Ni composite coating by pulse electrodeposition

Characterization of the microstructure and texture of functionally graded nickel-Al2O3 nano composite coating produced by pulse deposition

Effects of pore-crack relative location on crack propagation in porous media using XFEM method

Synthesis and mechanical properties of nickel-titania composite coatings