Ni-CeO2 Nanocomposite Coatings Research Articles

Development of CeO2 nanorods reinforced electrodeposited nickel nanocomposite coating and its tribological and corrosion resistance properties

A simple electrodeposition technique was used to prepare Ni-CeO2 nanorods composite coating (Ni-CeO2 NRs) using Watt's nickel plating bath containing CeO2 nanorods (NRs) as the reinforcement phase under optimized process conditions. The X-ray diffraction analysis (XRD) was used for the structural analysis of Ni-CeO2 NRs composite coatings and their average crystalline size is ∼22 nm for pure Ni and ∼18 nm, respectively. The crystalline structure is fcc for the Ni-CeO2 nanocomposite coatings. The surface morphology of the electrodeposited Ni-CeO2 NRs composite coatings was analyzed by scanning electron microscopy (SEM). Microhardness of pure Ni and Ni-CeO2 NRs composite coatings are found to be 253 HV and 824 HV, respectively. The inclusion of CeO2 NRs increases the microhardness of Ni-CeO2 NRs composite coatings. The corrosion resistance behavior of Ni-CeO2 NRs composite coating was evaluated by Tafel polarization and AC impedance methods. It is revealed that CeO2 NRs reinforced Ni matrix shows higher microhardness and corrosion resistance than existing reported electrodeposited pure Ni and CeO2 nanoparticles reinforced Ni coatings.

Characterizations of Ni-CeO2 nanocomposite coating by interlaced jet electrodeposition

The properties of conventional nickel coatings were improved by preparing Ni-CeO2 nanocomposite coatings by jet electrodeposition. On the basis of these results, a new method involving discontinuous cathode rotation and interlaced deposition was proposed. The effects of nanoparticle (NP) concentration and interlacing technology on the surface quality, NP content, and microstructure and corrosion resistance of the resulting composite coatings were investigated. The microstructure and surface morphology were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), the corrosion resistance was tested by electrochemical workstation. The results showed that, adding an appropriate amount of CeO2 NPs, effectively improved coating surface quality and reduced defects, such as cellular bulges, micropores, and microcracks. The corrosion current density was reduced from 1.612 to 0.459 μA cm−2, compared to pure Ni, which indicated that corrosion resistance was clearly improved. With the introduction of interlacing, the coating NP content increased up to 4.76 wt %, higher than the 4.25 wt % of conventional jet electrodeposition. The resulting coating surfaces were more uniform and smooth, and the problem of coating quality deterioration in traditional jet electrodeposition because of excessive NP addition was somewhat improved. With interlaced deposition, the corrosion current density was further reduced to 0.349 μA cm−2, with the coating corrosion further enhanced.

Self-healing effects by the Ce-rich precipitations on completing defective boundaries to manage microstructures and oxidation resistance of Ni-CeO2 coatings

This paper presented an effective approach for electroplating of coatings on the activated surface of pure Ti substrate using pulsed electro deposition. Regarding the ceramic-like TiO2 barrier layer on its surface of Ti substrate to inhibit surface activity, a novel activating solution that composed of HF, HCl, Ce(NO3)2, TiCl3, and bal. DMF dissolvent was applied for surface modifications of Ti substrate in order to increase interfacial bonding strength of surface Ni coatings. Besides a comparative study of Ni nanocrystalline coatings without and with CeO2 addition was carried out for disclosing the role of the Ce-rich phase on managing microstructure and high-temperature oxidation resistance during oxidation at 800 or 1000°C. Results indicated that Ce-rich precipitations, where dispersed along grain boundaries (GBs), were favorable for completing the spalling oxide-layers on Ni-CeO2 nanocomposite coatings during oxidation at 800°C. Furthermore, an analytical modeling was validated for better understanding of Ce-rich precipitations along GBs defects for monitoring oxidation mechanisms. Furthermore, this finding would be therefore leading to the guidelines for Ce-rich precipitations on the strengthening of Ni-based superalloys.

Synthesis and properties of electrodeposited Ni–CeO2 nano-composite coatings

Current machinery requires metallic materials to have better surface properties. Based on an orthogonal experimental design and analysis method, the CeO2-reinforced nickel nano-composite coatings were prepared by direct current electrodeposition in a nickel sulfate bath containing CeO2 nanoparticles. Statistical results indicate that current density is the most significant variable in the electrodeposition processing, while temperature is the least important factor. The microstructure of Ni and Ni–CeO2 nano-composite coatings was characterized by scanning electron microscopy (SEM) equipped with energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The microhardness of the Ni coating is enhanced by the incorporation of CeO2 nanoparticles. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to characterize the corrosion behavior of Ni and Ni–CeO2 coatings. These studies show that Ni–CeO2 coating has better corrosion resistance compared to Ni coating.

Anodized porous titanium coated with Ni-CeO2 deposits for enhancing surface toughness and wear resistance

In order to make large improvements of surface toughness and wear resistance for pure titanium (Ti) substrate, anodic titanium oxide (ATO) surface with nanoporous structure was coated with the Ni-CeO2 nanocomposite coatings. Regarding TiO2 barrier layer on Ti surface to inhibit its electrochemical activity, pre-treatments were successively processed with anodizing, sensitizing, activating, and then followed by electroless Ni-P film to be acted as an activated layer for electroplating Ni-CeO2 deposits. The existing Pd atoms around ATO nanopores were expected as the heterogeneous nucleation sites for supporting the growing locations of electroless Ni-P film. The innovative of interface design using porous structure was introduced for bonding pinholes to achieve a metallurgical adhesion interface between Ti substrate and surface coatings. Besides the objectives of this work were to elucidate how effects by the adding CeO2 nanoparticles on modifying microstructures and wear mechanisms of Ni-CeO2 nanocomposite coatings. Many efforts of XRD, FE-SEM, TEM and Nanoindentation tests were devoted to comparing different wear behaviors of Ni-CeO2 coatings relative to pure nickel. Results indicated that uniform-distributed Ti nanopores with an average diameter size of ∼200nm was achieved using the Phosphate-type anodizing solution at DC 150V. A worn surface without fatigue cracks was observed for TAO surface coated with Ni-CeO2 deposits, showing the existing Ce-rich worn products to be acted as a solid lubricant phase for making a self-healing effect on de-lamination failures. More important, this finding will be the guidelines for Ce-rich precipitations to be expected as the strengthening phase in anodized porous of Ti, Al and Mg alloys for intensifying their surface properties.

Preparation and Characterization of Electrodeposited Ni-CeO2 Nanocomposite Coatings with High Current Density

Preparation and Characterization of Electrodeposited Ni-CeO2 Nanocomposite Coatings with High Current Density

Characterizations of electrodeposited Ni–CeO2 nanocomposite coatings

The expansion of current machinery requires metallic materials with better surface properties. In the present investigation, CeO2 reinforced nickel nanocomposite coatings were deposited on mild steel substrate by direct current electrodeposition process employing nickel acetate bath. The effect of incorporation of CeO2 particles in the Ni nanocomposite coatings on the micro hardness and corrosion behaviour has been evaluated. Smooth and compact nanocomposite deposits containing well-distributed cerium oxide particles were obtained. The crystallite structure was fcc for electrodeposited nickel and Ni–CeO2 nanocomposite coatings. It has been observed that, the presence of CeO2 nanoparticles favours the [111] and [200] texture of nickel matrix. The co-deposition of CeO2 nanoparticles with nickel was found to be favoured at applied current density of 8 A dm−2. The micro hardness values of the nickel nanocomposite coatings (725 HV) was higher than that of pure nickel (265 HV).The decrease in Icorr values and increase in Constant Phase Element values were investigated in 3.5% NaCl solution which showed the higher corrosion resistant nature of Ni–CeO2 coatings.

Enhancement of microhardness and wear resistance of Ni–CeO2 nanocomposite coatings

The improvement of the incorporated nanoparticle content in nanocomposite coatings is a key factor in composite electrodeposition. This paper describes a modified sediment co-deposition (SCD) technique which has been developed to produce Ni–CeO2 nanocomposite coatings, with the aim of enhancing the embedded CeO2 nanoparticle content. The maximum content of CeO2 particles in the nanocomposite coatings created using this modified SCD technique is 7·09 wt-%, which is the highest reported. A maximum microhardness of 630 HV is obtained, which is significantly greater than that observed in nanocomposite coatings fabricated using the conventional electrodeposition technique. As the wear resistance of the nanocomposite coatings increases with increasing incorporated CeO2 nanoparticle content, so this nanocomposite coating with an incorporated CeO2 nanoparticle content of 7·09 wt-% exhibits maximum wear resistance.

Fabrication of Ni-CeO2 Nanocomposite Coatings Synthesised via a Modified Sediment Co-Deposition Process

Fabrication of Ni-CeO2 Nanocomposite Coatings Synthesised via a Modified Sediment Co-Deposition Process

Preparation and oxidation behaviour of electrodeposited Ni–CeO2 nanocomposite coatings

Ni–CeO2 nanocomposite coatings with different CeO2 contents were prepared by codeposition of Ni and CeO2 nanoparticles with an average particle size of 7 nm onto pure Ni surfaces from a nickel sulfate. The CeO2 nanoparticles were dispersed in the electrodeposited nanocrystalline Ni grains (with a size range of 10–30 nm). The isothermal oxidation behaviours of Ni–CeO2 nanocomposite coatings with two different CeO2 particles contents and the electrodeposited pure Ni coating were comparatively investigated in order to elucidate the effect of CeO2 at different temperatures and also CeO2 contents on the oxidation behaviour of Ni–CeO2 nanocomposite coatings. The results show that the as-codeposited Ni–CeO2 nanocomposite coatings have a superior oxidation resistance compared with the electrodeposited pure Ni coating at 800 °C due to the codeposited CeO2 nanoparticles blocking the outward diffusion of nickel along the grain boundaries. However, the effects of CeO2 particles on the oxidation resistance significantly decrease at 1050 °C and 1150 °C due to the outward-volume diffusion of nickel controlling the oxidation growth mechanism, and the content of CeO2 has little influence on the oxidation.

Synthesis of Ni-CeO<sub>2</sub> Nanocomposite Coatings by Electroforming

In this paper, the effect of CeO2 nanoparticles content in the bath on the weight percent of CeO2 particles, morphology, texture, and high temperature oxidation resistance of the nanocomposite coatings was examined. With a rise in the loadings of CeO2 particles in the bath from 10 gl-1 to 40 gl-1, the CeO2 particles weight percent in the nanocomposite coatings gradually increases. Further increased the loadings of particles in the bath to 50 gl-1, the weight percent reversely reduces. The maximum of CeO2 nano particles weight percent in the nanocomposite coatings is 4.98 wt% obtained at current density of 3 Adm-2 from the bath containing 40 gl-1 CeO2 particles. The high temperature oxidation resistance of Ni-CeO2 nanocomposite coatings significantly rise compared with that of bare nickel coatings, and enhanced with a rise in the loadings of CeO2 nano particles from 10 gl-1 to 30 gl-1. The wear resistance of deposits is also consist with the nanoparticles content in the bath。

Synthesis and Properties of Pulse Electrodeposited Ni-CeO2 Nanocomposite

Ni-CeO2 nanocomposite coatings were pulse electrodeposited from the Watt’s electrolyte containing different concentrations of nanosized CeO2 particles (10, 20, 30, 40, and 50 g/L). The microhardness, thermal stability, and corrosion resistance of these coatings were evaluated and compared with those of pure nanocrystalline Ni deposited under the same conditions. The results show that the Ni-CeO2 nanocomposite coating, synthesized from the electrolyte containing 30 g/L CeO2, has significantly higher hardness, thermal stability, and corrosion resistance than those of the pure nanocrystalline Ni and other Ni-CeO2 nanocomposite coatings.

Corrosion Resistance of Ni-CeO<sub>2</sub> Nanocomposite Coating Prepared by Electrodeposition with Rotating Cathode in an Ultrasonic Field

Ni-CeO2nanocomposite coatings were prepared by electrodeposition with rotating cathode in an ultrasonic field. The surface morphology of the coatings was examined. Effects of different electrodeposition methods, ultrasonic power and cathode rotating speed on the corrosion rate of Ni-CeO2nanocomposite coatings were analyzed. The results show that the corrosion rate of the coatings decreases considerably with the increasing of ultrasonic power, and suitable cathode rotating speed could decrease the corrosion rate of coatings. During the process of electrodeposition, the CeO2nanoparticles, ultrasonic and rotating cathode influence on the surface morphology of the coatings. The nanocomposite coating obtained by rotating cathode in an ultrasonic field exhibits refined crystal grains and presents an excellent corrosion resistance.

Effect of Current Density on the Microstructure and Hardness of Ni–CeO<SUB>2</SUB> Nanocomposite Coating Synthesized by Pulse Electrodeposition Technique

The Ni-CeO2 nanocomposite coatings have been synthesized by pulse electrodeposition technique with different current densities (0.10, 0.30, 0.40, 0.50, 0.70 and 0.90 A/cm2) from a Watts-type electrolyte containing nano-sized ceria particles. The Ni-CeO2 coatings produced with different current densities have been characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) coupled with an energy dispersive spectrometer (EDS). The hardness of the coatings has been measured by Vickers microhardness tester (VMHT). It has been found that the crystallite size decreases and hardness increases with the increasing current density. However, the co-deposition of ceria in the nickel matrix increases up to the current density of 0.5 A/cm2, beyond which it decreases.

Effect of surfactant on the co-electrodeposition of the nano-sized ceria particle in the nickel matrix

Abstract The nickel–ceria (Ni–CeO2) nanocomposite coatings have been pulse electrodeposited from a Watts-type electrolyte containing nano-sized CeO2 particles produced by high-energy ball milling technique (HEBM). Sodium Lauryl Sulphate (SLS) has been added in the electrolyte as a cationic surfactant. The effects of the surfactant on the zeta potential, co-deposition and distribution of ceria particles in the nickel matrix and hardness of composite coatings have been investigated. Experimental results show that the addition of SLS up to 0.10 g/l increases the amount of co-deposited ceria particles in the nickel matrix and microhardness of the nanocomposite. However, when the amount of SLS in the electrolyte is more than 0.1 g/l, there is a tendency to form agglomerates of ceria particles in the nickel matrix resulting no further increase in hardness of the Ni–CeO2 nanocomposite coatings.