Ni Coatings Research Articles

Electrochemical exfoliation of graphene nanosheets and development of a novel efficient Ni-CeO2-Gr ternary nanocomposite coatings for dual functional anti-corrosion and wear-resistance

Nickel-based coatings offer excellent corrosion, wear resistance, and mechanical strength, and can be further improved with additives, making them ideal for harsh environments like marine and chemical industries. In the present study, graphene (Gr) nanosheets were synthesized via electrochemical exfoliation and a novel Ni-CeO2-Gr nanocomposite coating was prepared by an electrochemical co-electrodeposition technique on a Cu substrate in a traditional Watts bath. The coatings (pure Ni, Ni-Gr, Ni-CeO2 and the ternary Ni-CeO2-Gr) were characterized using optical microscopy, scanning electron microscopy (SEM) coupled with energy-dispersive spectrometry (EDS), X-ray diffraction (XRD), Raman spectroscopy, Vickers microhardness and micro-scratch tests. The electrochemical properties of the coatings were evaluated by electrochemical impedance (EIS) and DC-polarization measurements in 0.5 M NaCl. SEM-EDS, Raman, and XRD analysis confirmed the successful synthesis of high-quality graphene and the incorporation of CeO2 nanoparticles and graphene nanosheets into the nickel coating matrix. It was found that the ternary Ni-CeO2-Gr coating exhibited a high microhardness (915.6 HV), improved cohesive strength and enhanced corrosion resistance (544 KΩ.cm−2) compared to pure Ni coatings (30 KΩ.cm−2) due to the synergistic effect of the graphene and CeO2 duplex layer within the Ni matrix, forming a robust anticorrosion barrier. These findings offer valuable insights into the designing highly efficient materials for corrosion protection.

Effect of laser-induced grain growth on the electrochemical and immersion corrosion behavior of electrochemical deposited Ni coatings

In this study, the introduction of laser irradiation during the electrochemical deposition of Ni coatings was employed to investigate the evolution of surface morphology, microstructure, and residual stress. Furthermore, the impact of laser on corrosion performance was examined through electrochemical and immersion corrosion tests. The results showed that introducing a laser resulted in a uniform electrochemically deposited particle size distribution, and the shape evolved from granular to pyramidal. However, the average grain size increased from 0.4 ± 0.1 μm to 0.6 ± 0.3 μm after adding laser, and the grain morphology also transformed from equiaxed to columnar grains. In addition, the surface roughness increased from 34 ± 3 nm to 122 ± 16 nm compared to not adding a laser. The internal stress changed from 54 ± 17 MPa to −113 ± 19 MPa, indicating that the original tensile stress evolved into compressive stress. Electrochemical and immersion corrosion indicate that after adding laser, the passive current density decreased from 3.8 × 10−6 A·cm−2 to 6.9 × 10−7 A·cm−2 (reduced by approximately 81.8 %), indicating a significant improvement in corrosion resistance. This is attributed to the stability and density of the passive film. Although the average grain size and surface roughness increase, the uniformity of surface deposited particles improves the uniformity of electrochemical distribution, accelerates the formation of uniformly dense passive film, and limits the expansion of corrosion pits under the combined action of compressive stress.

Controlled Compositions in Zn–Ni Coatings by Anode Material Selection for Replacing Cadmium

Cadmium-based coatings have long been used to protect high-strength steel in aerospace, but due to cadmium’s toxic and carcinogenic nature, its use is increasingly restricted. Zinc–nickel coatings, containing 10–14 wt% Ni, offer superior corrosion resistance compared to pure zinc, making them a promising alternative. However, Zn–Ni coatings are prone to cracking, which can compromise their protection. This study investigates how different anode materials influence crack formation and coating properties during electrodeposition. Zinc and nickel anodes produced coatings with consistent thicknesses of 13–15 µm, while 1020 steel and stainless steel resulted in thicker coatings of up to 33 µm. Notably, coatings deposited with nickel anodes demonstrated strong adhesion and consistent interface quality. Zinc anodes achieved a high Ni content of about 13.5 wt%, whereas 1020 steel and stainless steel produced lower Ni content, around 7 wt%. Additionally, zinc and nickel anodes led to fewer defects and minimal porosity, in contrast to the higher porosity observed with 1020 steel and stainless steel anodes. Furthermore, zinc anodes maintained stable voltages (~0.5 V), contributing to more uniform coatings. In terms of corrosion resistance, zinc anodes exhibited a lower corrosion rate of 0.44 mm/year compared to 1.54 mm/year for nickel anodes. This study highlights the importance of anode selection in reducing cracking and optimizing Zn–Ni coatings, presenting them as a safer and more effective alternative to cadmium-based coatings.

Influence of added La2O3 on the microstructure, mechanical properties, and tribocorrosion resistance of TiB2–Ni plasma-sprayed coatings

To enhance the tribocorrosion resistance of 7075-T6 aluminum alloy in deep sea environments, TiB2–Ni coatings with varying La2O3 content were deposited on 7075-T6 aluminum alloy substrates using plasma spray technology. The effects of different La2O3 contents on the organization, structure, and properties of the coatings were analyzed. The results indicated that La2O3 incorporation suppressed brittle phase formation such as Ni3B; 1.0 wt% La2O3 addition reduced Ni3B by 16.9%. The coating's corrosion resistance significantly improved with La2O3 doping - the self-corrosion current density of the 1.0 wt% La2O3-doped coating decreased from 71.2 nA/cm2 to 30.2 nA/cm2.

Defect formation and growth in metal nanocomposites consisting of Cu nanoparticles embedded in Ni or Al coatings

Fully inorganic or metallic nanocomposite coatings are promising materials for various applications but face limitations in term of their synthesis. A complementary synthesis process, Physical Vapor Deposition combined with magnetron sputtering and plasma-assisted gas-phase aggregation produced Cu nanoparticles embedded in metallic matrix. In this study, the effect of embedded nanoparticles on the matrix structure was investigated. Al and Ni were selected as matrix materials due to their different sputter yields leading to different growth modes film morphologies and difference in surface energy. Depending on the nanocomposite and deposition conditions, defects such as nodular growth were occasionally observed. These growth anomalies originated from the presence of nanoparticles creating new nucleation points for the matrix to grow disturbing the grain growth around it. Key factors responsible for their formation include the surface energy difference between the NPs and the matrix and the geometrical disruption occurring for large NP. In extreme cases with a high concentration of nanoparticles, coatings entirely constituted of nodular defects were produced which can be advantageous for applications needing large specific surface area.

Influence of pulse frequency on microstructure, mechanical properties, and corrosion resistance of electrodeposited Ni-SiC composite coatings

The current study explores the effects of SiC co-deposition in Ni matrix during pulse electrodeposition (PED) at various pulse frequencies. X-Ray Diffraction (XRD) analysis indicates that at lower frequencies, the composite coating favours the (111) plane orientation, while at higher frequencies (50 and 100 Hz), it changes toward the (200) plane. Scanning Electron Microscopy (SEM) analysis shows a decrease in SiC particle content with increasing frequency. Coatings deposited at 10 Hz display a compact, uniform structure with higher SiC particle concentration, resulting in smoother surfaces compared to pure Ni coatings. This leads to higher hardness (440 HVN) compared to coatings deposited at higher frequencies (425 HVN and 410 HVN for the 50 Hz and 100 Hz, respectively). Furthermore, the composite coatings exhibit superior corrosion resistance, with reduced electrolyte penetration and localized corrosion relative to pure Ni. Notably, the 10 Hz coating demonstrates a lower corrosion rate of 0.005 mm/year and a higher corrosion protection efficiency of 88 %. Therefore, SiC co-deposition at 10 Hz acts as a protective barrier, inhibiting corrosion progression and enhancing long-term durability against corrosion.

Friction and Wear Characteristics of Electrodeposited Ni‐Based Metallic Coatings on Cu‐Substrate under High‐Temperature Conditions

The Ni self‐lubricating coatings on copper substrates are deposited by electrodeposition using an aqueous electrolyte at room temperature. These coatings have the potential to improve the service life of Cu as a structural component in high‐temperature abrasion environments. A combination of low wear rate and coefficient of friction (CoF) is required in the coatings. Herein, friction and wear characteristics of the deposited Ni coatings are done by a ball‐on‐disc tribometer operated in the temperature range of 25–500 °C. The morphology and wear mechanism of tribo/transfer films are investigated using X‐ray diffraction, X‐ray photoelectron spectroscopy, and scanning electron microscopy. The CoF of Ni coating is substantially lower (CoF 0.37) at 500 °C than the Cu‐substrate, which is 0.79 at 25 °C. The Ni‐coating also reveals a low wear rate due to the formation of in situ oxides of Ni and Cu on sliding surfaces at high temperatures.

Tribological Properties of Laser-Cladded NiCrBSi Coatings Undergoing Friction with Ti6Al4V Alloys

This work aims at reducing abrasion between titanium alloy parts, such as drive shafts and support pairs used in aviation. Three different NiCrBSi coatings, Ni40, Ni50, and Ni60, are prepared on surfaces of Ti6Al4V by laser cladding. The microstructural and mechanical properties of these coatings are analyzed by scanning electron microscope (SEM) and a microhardness tester. The tribological properties of the NiCrBSi coatings undergoing friction with Ti6Al4V are tested using a wear testing machine. The results show that the Vickers hardnesses of the Ni40, Ni50, and Ni60 coatings are 490 HV0.3, 609 HV0.3, and 708 HV0.3, respectively. For the above NiCrBSi coatings, more hard phases are produced with increases in the amounts of Cr in the powders, resulting in increases in the coatings’ hardnesses. The wear test results show that the NiCrBSi coatings could reduce the friction coefficients, which gradually decreased with increases in the coatings’ hardnesses. Both the coating-specific wear rates and the friction pair wear losses initially decreased and then increased. The Ni50 coating and the Ti6Al4V friction pair undergoing friction with the Ni50 coating showed the best wear performance, with a specific wear rate and wear loss of 0.51 × 10−7 mm3/(N·m) and 7.8 mg, respectively. The specific wear rates for Ni50 were only 8.4%, 35.4%, and 37.0% of the Ti6Al4V, Ni40, and Ni60, respectively. In addition, the friction pair wear loss was only 36.4%, 52.5%, and 55.3% of that while undergoing friction with Ti6Al4V, Ni40, and Ni60, respectively. The NiCrBSi coatings prepared on the surface of Ti6Al4V show excellent antifriction and wear resistance properties, providing a viable solution for the design of wear-resistant coatings on load-bearing and non-load-bearing titanium alloy parts.

Thermal shock resistance of WC–Cr3C2–Ni coatings deposited via high-velocity air fuel spraying

In this study, the high-velocity air fuel (HVAF) spraying technique was used to deposit WC–Cr3C2–Ni wear-resistant coatings on the surface of crystallization rollers to overcome the wear problem of the substrate of thin-strip continuous-casting crystallization rollers and thus improve their efficiency. The performance and durability of the WC–Cr3C2–Ni coatings on the surface of the roller body during the actual continuous casting process were investigated by performing thermal shock tests. It was found that the thermal shock resistance of the closed-curved surface coatings increased with their thickness. The coatings exhibited the best thermal shock resistance at a thickness of 300 μm, and the number of cycles they could withstand at 800 °C reached 15. The results of the high-temperature wear tests showed that the WC–Cr3C2–Ni coatings deposited on the surface of the crystallization roller via HVAF reduced the friction coefficient of the surface of the roller body (from 0.425 to 0.362), and greatly reduced the wear loss volume during the wear process (reduced by 83 %). The WC-Cr3C2-Ni coating showed excellent resistance to crack initiation and propagation during wear and can be stabilized in long-cycle production and protect the substrate of the crystallization roller effectively. This study provides a theoretical basis for the selection and preparation of surface coatings for thin-strip continuous-casting crystallization rollers.

Role of Substrate on the Fractal Characteristics of Nanostructure Surfaces of Electrodeposited Nickel Thin Films

This study investigates the structure, morphological, and roughness properties of electrodeposited nickel thin films grown on different substrates, that is, silicon, copper, and gold. X‐ray diffraction analysis reveals that the Ni coatings exhibit a face‐centered‐cubic phase, regardless of the substrate used, although the texture is mainly influenced by the substrate. Atomic force microscopy images show that larger grains are obtained with gold substrates, while smaller ones are observed with copper and silicon substrates, in agreement with scanning electron microscopy. The results demonstrate that both topological and fractal characteristics of the Ni thin films are significantly influenced by the type of substrate. Statistical parameters are quantified to compare the surface morphology of the different samples. Fractal analysis reveals that the fractal dimensions of all surfaces range between 2 and 3, indicating self‐affinity. Fractal succolarity and lacunarity are measured to assess the penetration of a liquid into the surface and the distribution of gaps in the Ni film surfaces, respectively. Minkowski functionals are utilized for topological analysis to characterize the internal structure of the Ni thin films. The observed differences in roughness characteristics provide evidence that the type of substrate affects the nucleation and growth of surface features during electrodeposition.

Ultrasonic-assisted pulse electrodeposition process for producing nanocrystalline nickel films and their corrosion behavior: Competition between mass transport and nucleation

Ultrasonic-assisted pulse electrodeposition of nanocrystalline nickel (NC-Ni) coatings from Watts bath on copper substrate was investigated. Direct (DC), pulsed (PC), and pulse reversed (PRC) current electrodeposition techniques were employed to electrodeposit NC-Ni coatings in the absence and presence of ultrasound wave with a nominal power ranging from 95 W to 200 W and their surface morphology, hardness, and crystalline microstructure were compared. We observed that as the ultrasound power increases, the cathodic efficiency and the microhardness increase, whereas the crystallite size and surface roughness decrease for NC-Ni electrodeposited by the three techniques in the same way. However, the effect of pulse waveform is dominant. The finest crystallite size (24 nm) and highest hardness (585 HV) were achieved for NC Ni coatings PC electrodeposited using an ultrasound with 200 W nominal power. It is believed that the coating produced by PC and PRC techniques develops a preferential orientation in (111) and (100) planes, respectively. The application of ultrasound wave and increasing its nominal power changes the preferential orientation of all obtained coatings to (111) planes. The corrosion behavior of NC Ni coatings, as investigated by potentiodynamic polarization and electrochemical impedance spectroscopy in NaOH solution, demonstrates the effect of nanocrystalline on the passivation and corrosion resistance of NC-Ni coatings.

High-efficiency electromagnetic shielding of three-dimensional laminated Wood/Cu/Ni composites

Construction of ideal dissipation path for layered electromagnetic shielding materials (EMSM) is promising but challenging. Herein, high-efficiency EMSM of three-dimensional hydrophobic wood/Cu/Ni laminated composites have been constructed to achieve laminated composites with high electromagnetic shielding efficiency and low reflection. The electromagnetic gradient structures are obtained via different Cu and Ni deposition times, where the slightly magnetic top Ni coatings serves as electromagnetic (EM) absorption layer and the highly conductive Cu coatings as reflection layer. The hierarchical porous wood structure could extend the EM dissipation path and dissipate EM by multiple reflections. Therefore, the laminated structure exhibits an excellent EM shielding efficiency (average 91.6 dB) at only 0.45 mm thickness between 8.2 GHz and 12.4 GHz in frequency. In addition, the contact angle of laminated composites was 117.8° and the Joule heating was nearly to 0, which broaden their application scenarios in practice. Furthermore, the multilayer Cu/Ni wood-based composites with sandwich-structured can be used as EM shielding gaskets and effectively block wireless power transmission and high frequency EM signal, which shows a prosperous application prospect in defense industry and aerospace.

Microstructure and Tribological Properties of In situ-Synthesized WC-Reinforced Ni60 Coatings Prepared by Laser Cladding with Different Scanning Rates

Microstructure and Tribological Properties of In situ-Synthesized WC-Reinforced Ni60 Coatings Prepared by Laser Cladding with Different Scanning Rates

A novel design method for NiCr coating against supercritical CO2 via the ReaxFF molecular dynamics theoretical analysis and experimental verification

In order to design a NiCr coating with the strongest corrosion resistance, the corrosion behavior of Ni, Ni10Cr and Ni20Cr coatings was studied using molecular dynamics, in which Ni20Cr coating exhibited the best corrosion resistance. The corrosion behavior of Fe9Cr heat-resistant steel with or without Ni20Cr coating in a supercritical CO2 at 650 ℃ and 15 MPa for 1000 h was carried out by corrosion test, which significantly reduced the experimental period and cost. The Ni20Cr coating was intact and uniform after exposure for 1000 h. A dense and continuous Cr-rich oxide film with low growth stress could rapidly formed on the Ni20Cr coating. The Ni20Cr coating could effectively enhance the corrosion and carburization resistance of Fe9Cr heat-resistant steel.

Investigation on tribological properties of high-velocity air fuel spraying WC–Cr3C2–Ni coating on the surface of continuous casting crystallization rollers

To overcome the wear problem of the substrate of thin-strip continuous casting crystallization rollers and improve economic efficiency, high-velocity air fuel (HVAF) technology was used to deposit WC–Cr3C2–Ni wear-resistant coatings on the surface of the crystallization rollers. The existing performance and wear condition of curved WC–Cr3C2–Ni coatings during continuous casting were investigated by the ring-block wear system. The experimental results showed that the WC–Cr3C2–Ni coating with a thickness of 300 μm effectively reduced the coefficient of friction (by 16.4 %) and the wear rate (by 82.5 %) on the surface of the crystallization roller and significantly reduced the roughness of the wear interface (by 71.2 %), which provided reliable protection for the substrate. The results of high-temperature (200 °C) wear tests showed that the WC–Cr3C2–Ni coating deposited via HVAF protected the substrate in actual long-cycle production and exhibited an excellent resistance to the emergence and expansion of failure cracks. This study provided a theoretical basis for the selection and preparation of surface coatings for thin strip continuous casting crystallization rollers.

Investigation of the X‐ray fluorescence technique in the characterization of Ni coatings applied to historical heritage studies

AbstractHistorical heritage pieces allow a better comprehension of the characteristics of different civilizations over time. The characterization of such pieces is of paramount importance for their preservation. Energy‐dispersive X‐ray fluorescence (EDXRF) is recommended for this application, mostly because it is non‐destructive and the equipment is portable. However, one of its limitations is the difficulty in separating the signal from the substrate and the coating of multilayered samples, as it does not provide depth resolution. This project investigates the application of EDXRF in the characterization of metallic coatings, in the context of historical heritage. The elemental concentration of electrodeposited Ni coatings onto carbon steel substrates was obtained from EDXRF analyses. The relationship between the layer thickness and the variation of the Kα/Kβ intensity ratio of nickel peaks was exploited and the thicknesses of the coatings were estimated through EDXRF measurements. For comparison, particle‐induced x‐ray emission spectroscopy and scanning electron microscopy of the cross‐section were employed, providing a depth profile of the coatings. The estimated thicknesses from EDXRF analysis were comparable to those observed in the microscopy images for thinner films (up to 8 μm). On the other hand, for thicker films, the thicknesses were underestimated, due to the technique's depth limit and matrix effects, as secondary absorption. Despite these limitations, EDXRF remains valuable for evaluating cultural heritage pieces, often providing sufficient information to address authenticity concerns or to guide restoration processes. A case study was also performed to apply the methodology discussed on historical metallic pieces.

The induced co-deposition of Ni–Mo–W ternary alloy; Coatings for hardness and corrosion resistance applications

Ni–Mo–W ternary alloy coatings were electrodeposited on mild steel substrate using citrate electrolyte for hardness and corrosion resistance applications. The influences electrolyte pH, electrolyte temperature and sodium molybdate concentrations on deposit qualities were studied. The sodium molybdate concentrations were varied from 0.025 to 0.1 M for obtaining alloy coatings with various molybdenum (Mo) compositions. The deposition condition such as electrolyte concentration, pH and temperature were optimized for obtaining good aesthetic (bright) appearance, surface stability and microhardness properties. The maximum Mo composition (47.71 wt %) in alloy deposit was achieved is 47.71 wt % using 0.1 M sodium molybdate concentration. The microhardness properties were increased from 850 HV to 946 HV by introducing molybdenum (47.71 wt %) as third alloying element in to Ni–W alloy matrix. The obtained mechanical and corrosion resistance properties of these ternary alloy coatings were compared with binary alloy and metallic coatings viz., Ni–W and Ni–Mo and metallic Ni coatings. The superior corrosion rate was observed for Ni–Mo–W alloy deposits (5.8 mpy) compared to Ni–W (9.04 mpy) and Ni–Mo (8.89 mpy) alloy.

Effect of alternating interval of laser power on the element distribution, mechanical, and corrosion performance of electrochemical deposited multilayer Fe–Ni coatings

A new multilayer (ML) Fe–Ni coating was developed by frequently alternating the laser power (5 and 20 W) during electrochemical deposition. Owing to the thermal effect of the laser, the elemental content in each layer changed continuously. As the intervals for adjusting the laser parameters became shorter, the formation of ML Fe–Ni coatings became increasingly challenging due to the laser's thermal effect. This study suggests that a constant laser action exceeding 480 s improves the uniformity of the alternating elemental content distribution in the new coating without visible interlayer boundaries. Moreover, the elemental composition of each layer was affected by various laser parameters during the Fe–Ni reduction process. For a stable ML structure (480 s interval), the range of variation in Fe content reaches approximately 16.6 wt% (from approximately 32.6 to 49.2 wt%). Compared with the overall coating, the bonding force increased by approximately 24.5 %, the microhardness increased by approximately 17.3 % (load of 200 g), the wear rate decreased by approximately 21.6 % (load of 5 N), and the corrosion rate decreased by approximately 53.5 % (3.5 wt% NaCl). The improved wear resistance was attributed to the inhibition of crack extension and spalling. In addition, the ML structure was conducive to inhibiting the propagation of corrosion pits. This study provides guidance for analyzing the structural and performance characteristics of ML coatings formed via laser electrochemical deposition.

Electrochemical Deposition and Properties of Ni Coatings with Nitrogen-Modified Graphene Oxide

In this study, a method for producing nitrogen-modified graphene oxide (NMGO) using hydrothermal synthesis in the presence of triethanolamine is presented. The composition and structure of NMGO are characterized using X-ray phase analysis (XPA), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and Raman spectroscopy. Ni-based metal matrix coatings (MMCs) modified with NMGO were obtained from a sulfate-chloride electrolyte in the galvanostatic mode. The process of electrochemical deposition of these coatings was studied using chronovoltammetry. The microstructure of Ni–NMGO MMCs was studied using the XPA and SEM methods. It has been established that the addition of NMGO particles into the Ni matrix results in an increase in the microhardness of the resulting coatings by an average of 1.30 times. This effect is a consequence of the refinement of crystallites and high mechanical properties of NMGO phase. The corrosion-electrochemical behavior of studied electrochemical deposits in 0.5 M sulfuric acid was analyzed. It has been shown that the corrosion rate of Ni–NMGO MMCs in a 3.5% sodium chloride environment decreases by approximately 1.50–1.70 times as compared to unmodified Ni coatings. This is due to NMGO particles that act as a barrier preventing the propagation of the corrosion and form corrosive galvanic microelements with Ni, promoting anodic polarization.

Electrodeposition of nanocrystalline Ni and NiCr alloy coatings: Effects of Cr content on microhardness and wear resistance improvement

The safety and reliability of high-speed trains depend on the brake disc. In order to improve the lifetime of brake disc and reduce the waste of resources, a coating with higher microhardness and well wear resistance is urgently needed. The effect of chromium content on the microstructure, microhardness and wear resistance of NiCr coating has been studied. Nano-crystalline Ni and NiCr coatings with superior mechanical properties were successfully prepared on the 30CrNiMo steel substrate by pulse current electrodeposition method. The inclusion of formic acid and sodium citrate was found to significantly expedite the co-deposition of Ni and Cr. The NiCr coatings with various Cr contents were prepared at current densities ranging from 200 to 300 mA/cm2. These coatings significantly enhance microhardness and wear resistance of the substrate. The microhardness of the NiCr coating increased to 603 HV, outperforming pure Ni coating by 119 HV. Additionally, the wear rate of the NiCr coating decreased by 50% at a load of 10 N in comparison to the Ni coating. The high microhardness is attributed to grain refinement and solution strengthening. This study successfully addresses the challenges associated with electrodepositing Ni-based coatings on 30CrNiMo steel substrate and lays a theoretical foundation for the utilization of Ni-based coatings to enhance the tribological properties of materials used in high-speed train brake disc.