Electroless Ni-P Composite Coatings Research Articles

Microstructural, mechanical and corrosion characterization of electroless Ni-P composite coatings modified with ZrO2 reinforcing nanoparticles

This study aims to develop medium P (MP, 6 wt%) and high P (HP, 11 wt%) Ni-P-ZrO2 nanocomposites on F22 steel substrate using an original lead-free and surfactant-free solution and to quantitatively relate nanocomposite characteristics to microhardness improvement and corrosion resistance. Incorporation, dispersion and distribution of the nanosized reinforcing phase were evaluated quantitatively by coupling Scanning Electron Microscope (SEM) imaging acquisition with original procedure for image processing and analysis. X-ray Diffraction (XRD) analysis revealed that nanoparticles introduction does not alter microstructure, which remains amorphous for HP and nanocrystalline for MP. Significant differences in particles distribution are found between MP and HP nanocomposites, which are induced by the difference in plating rate of the two formulations. Faster growth of MP (≈35 μm/h) associates with greater enveloping capability, with higher incorporation and agglomeration phenomena that result in non-uniform microhardness across the thickness. Conversely, the slower growth of HP nanocomposites coatings (≈20 μm/h) relates to lower but uniform incorporation and good dispersion of the reinforcing nanoparticles. Effective dispersion strengthening was observed for nanoparticles concentration up to 13.5 g/l. Microhardness increase by >25 % was achieved for both MP and HP coatings. The combined effect of nanoparticles incorporation level and their agglomeration was systematically studied and a mathematical model was implemented. It was demonstrated that strengthening effectiveness depends on both the amount of embedded nanoparticles and the mean size of agglomerates, following a bi-liner relation that reliably predicts experimental microhardness. Potentiodynamic corrosion test revealed that introduction of ZrO2 nanoparticles enhance corrosion resistance of both MP and HP coatings. The presented hardening strategy for Ni-P coatings can be an efficient solution for midstream and downstream applications in the oil&gas industry, in order to increase service-life of components in contact with both wearing and corrosive media.

Development of novel corrosion resistant electroless NI-P composite coatings for pipeline steel

In this research, coatings with various particles contents will be co-deposited within Ni–P deposits on AISI 1012 steel samples by electroless coating process. As a result, structural changes were evaluated, surface and cross-section morphology of composite deposits have been investigated by scanning electron microscopy (SEM), volumetric percentage of co-deposited particles have been determined using EDS analysis system, corrosion resistance of various EN coatings and current density were studied through potentiodynamic polarization, and mechanical properties were evaluated using wear and nano-indentation tests. The results showed that Alumina can give the best compromise between surface smoothness and deposition rate, Titanium can reach the highest levels of volumetric incorporation whereas Carbon can improve further lubrication effect on wear action, finally hardness and corrosion behavior had the best results with the existence of Alumina.

Preparation and tribological characterization of graphene incorporated electroless Ni-P composite coatings

Industrial application of electroless NiP coatings are limited by their low toughness and cracking under various loading conditions that in turn requires improvement of toughness using ternary coating systems. In this research work, graphene suspension was added to electroless NiP plating bath in various concentrations to produce four different compositions of Ni-P-G (graphene) coatings. Micro-structural and surface attributes were studied using SEM and white light profilometer respectively. Scratch and indentation behaviors of substrate and coatings were investigated. Graphene incorporation in NiP coating matrix improved the hardness as well as wear resistance. Also graphene supported NiP coating exhibited toughness through crack shielding and crack deflection phenomena.

Electroless Codeposition of Ni-P Composite Coatings: Effects of Graphene and TiO2 on the Morphology, Corrosion, and Tribological Properties

Given the excellent electrochemical and mechanical properties of graphene oxide (GO) and ceramic particles, excellent corrosion and tribological properties are expected when GO and TiO2 particles are incorporated into the Ni-P matrix. For this purpose, Ni-P composite coatings reinforced with GO and TiO2 ceramic particles were produced by electroless deposition. The structure, composition, morphology, microhardness, and corrosion resistance of the Ni-P and Ni-P composite coatings were analyzed using field emission scanning electron microscopy, X-ray diffraction, anodic polarization curves, and electrochemical impedance spectroscopy. The tribological behaviors of the Ni-P and Ni-P composite coatings were studied under dry conditions. The excellent corrosion and wear properties of the Ni-P-TiO2-GO composite coatings were attributed to the synergistic effects of the GO and TiO2 ceramic particles. It is expected that electroless Ni-P composite coatings reinforced with GO and TiO2 ceramic particles can establish a new trend, especially for engineering materials where wear resistance and corrosion are of importance.

Facile fabrication of super-hydrophobic FAS modified electroless Ni-P coating meshes for rapid water-oil separation

The development of the super-hydrophobic coating/film mesh for directly separating oil from water is greatly desired due to the high separation efficiency and the steady recyclability. Here we describe a facile and inexpensive method for fabricating the super-hydrophobic/super-oleophilic stainless steel meshes with the FAS modified electroless Ni-P composite coatings. The Ni-P particles on the mesh are spherical with a uniform size diameter and relatively concatenate each other to form a nanoscale rough surface. The static contact angles of the as-prepared meshes fall in between 124.4 ± 1.5° and 167.9 ± 2.1°. These meshes exhibit non-sticking of water, anti-fouling, and excellent penetrating through the oil properties. The prepared meshes can rapidly and continuously separate water-oil mixture without resorting to any extra driving force and the chemical agent. The best separation efficiency is 96.8%. The super-hydrophobic mesh is steady and reliable for a long-term separation of the water-oil mixtures. Finally, a separation mechanism of the super-hydrophobic meshes for the water-oil mixtures is proposed. We anticipate that the prepared meshes could provide a candidate application to effective waste oil cleanup and other rapid water-oil separation processes.

Preparation and characterization of micro or nano cellulose fibers via electroless Ni-P composite coatings

Ni-P composite coatings were prepared on cellulose fiber surface via a simple electroless Ni-P approach. The metal-coated extent, dispersion extent of micro or nano cellulose fibers and crystalline structure of Ni-P composite coatings were investigated. The homogeneous hollow composite coatings and metal-coated extent of micro or nano cellulose fibers were improved with the increase in ultrasonic power, and the ideal composite coatings were obtained as ultrasonic up to 960 W. The metallization for cellulose fibers enhanced the dispersion extent of micro or nano cellulose fibers. A uniform coating, consisting of the hollow coating on cellulose fibers surface, could be obtained. At the same time, metallization did not damage the original structure and surface functional groups of cellulose fibers. The concentration of cellulose fibers and ultrasonic power had a direct influence on the metal-coated extent of cellulose fiber surface. The metal-coated extent, dispersion extent of micro or nano cellulose fibers and crystalline structure of Ni-P composite coatings exhibited excellent properties as the concentration of cellulose fibers and ultrasonic power were 2 g/L and 960 W, respectively.

Fabrications of Electroless Ni-P Composite Coatings before and after Annealing and Tribological Analyses

In the present study, SiC reinforced particles were introduced to the Ni-P plating bath, and developed high SiC content composite coatings. Thin films nature properties and mechanical performances were evaluated well. The results showed that the Ni-P alloy embedded SiC particles formed a few cavities, and reduced coatings hardness and wear resistance in as-plated condition. After 400°C heat-treatment, Ni3P crystalline phase formed and reached the max hardness, and conducted excellent trybological performances. SiC particles were decoposited in 600°C and reacted with Ni to form Ni3Si and Ni5Si2, caused the decreasing in hardness.

Characterization and corrosion resistance of duplex electroless Ni-P composite coatings on magnesium alloy

Three different types of electroless nickel (EN)-phosphorus plating were applied on AZ31 wrought magnesium alloy. The first type was plain mid-phosphorus coating, the second one was duplex, with the first layer having a mid-phosphorus content and the upper one consisting of high-phosphorus whereas the third type of coating was also duplex with a first mid-phosphorus layer and a second high-phosphorus one with incorporated ceramic TiO2 and ZrO2 microparticles. Characterization of deposits by means of scanning electron microscopy and X-ray diffraction analysis proves the production of adherent, defect free coatings with differences in crystallinity depending on P content. Surface roughness was maintained at acceptable levels while a great increase in microhardness was observed that was further enhanced by ceramic microparticles incorporation. Electrochemical testing, that was performed by Tafel polarization in 3.5% NaCl solution, show that all the coatings effectively protect the Mg alloy substrate. Additionally, the composite coatings exceptionally enhance the protective capability of the system after heat treatment at 200°C.

Influence of fluorosurfactants on the codeposition of ceramic nanoparticles and the morphology of electroless NiP coatings

Electroless NiP composite coatings with SiC or Si 3N 4 nanoparticles were prepared from an additive-free bath. Cationic, anionic and non-ionic fluorosurfactants were used to try to avoid the agglomeration and the particle incorporation into the coating. Particle size and zeta potential were used to characterize the dispersion. The drawbacks of measuring these properties at the plating conditions (high ionic strength media and temperature) were discussed. Results indicated that the addition of low concentrations of fluorosurfactants did not modify the zeta potential of the particles in the bath but increased the amount of embedded particles. Moreover, the presence of the fluorosurfactants, mainly the non-ionic one, had a positive effect on the surface roughness and performance of NiP composite coatings.

Electroless NiP micro- and nano-composite coatings

Electroless NiP composite coatings were obtained by incorporating two kinds of particles, SiC and Si 3N 4, to analyze the influence of the type of particle both on the codeposition process and on the coating properties. Particles with sizes ranging from 30 nm to 2 μm were selected to study the influence of this parameter on the amount of embedded particles. All composite coatings were characterized by composition, morphology, structure, roughness and some tribological properties. Results indicated that, while there was almost no difference between carbide and nitride incorporation for micron-sized particles, this variable was very important with the nano-sized ones. Moreover, it was observed that the growth mechanism of the metallic matrix was much more modified by the nano-particles than by the micron-sized ones.

Electroless Ni-P composite coatings

Electroless Ni-P composite coatings

Electroless Ni-P composite coatings

This review outlines the development of electroless Ni–P composite coatings. It highlights the method of formation, mechanism of particle incorporation, factors influencing particle incorporation, effect of particle incorporation on the structure, hardness, friction, wear and abrasion resistance, corrosion resistance, high temperature oxidation resistance of electroless Ni–P composite coatings as well as their applications. The improvement in surface properties offered by such composite coatings will have a significant impact on numerous industrial applications and in the future they will secure a more prominent place in the surface engineering of metals and alloys.

Evaluation of the corrosion resistance of electroless Ni-P and Ni-P composite coatings by electrochemical impedance spectroscopy

Electroless Ni-P composite coatings have gained a good deal of popularity and acceptance in recent years as they provide considerable improvement of desirable qualities such as hardness, wear, abrasion resistance, etc. The disagreement among researchers on the corrosion behaviour of these coatings warrants a thorough investigation. Among the various techniques available for the determination of corrosion resistance, electrochemical impedance spectroscopy (EIS) is considered to be superior as it provides not only an assessment of the corrosion resistance of different deposits but also enables the mechanistic pathway by which the deposits become corroded to be determined. The present investigation focuses on the evaluation of the corrosion resistance of electroless Ni-P and Ni-P-Si3N4, Ni-P-CeO2 and Ni-P-TiO2 composite coatings produced using an acidic hypophosphite-reduced electroless nickel bath, using EIS. The study makes evident that the same fundamental reaction is occurring on all the coatings of the present study but over a different effective area in each case. The charge transfer resistance of electroless Ni-P and Ni-P composite deposits are in the range 32,253–90,700 Ω cm2, whereas the capacitances of these coatings are in the range 11–17 µF/cm2. The improved corrosion resistance obtained for electroless Ni-P and Ni-P composite coatings is due to the enrichment of phosphorus on the electrode surface, which enables the preferential hydrolysis of phosphorus over that of nickel. The better corrosion resistance obtained for electroless Ni-P composite coatings can be ascribed to the decrease in the effective metallic area prone to corrosion. Among the three electroless Ni-P composite coatings, the corrosion resistance is in the following order: Ni-P-CeO2=Ni-P-Si3N4>Ni-P-TiO2.