Electroless Nickel Phosphorus Plating Research Articles

Machine learning for aspherical lens form accuracy improvement in precision molding of infrared chalcogenide glass

Precision glass molding (PGM) is an effective approach to manufacturing infrared chalcogenide glass (ChG) aspherical lens with complex shapes. However, infrared ChG aspherical lens often experiences form error in the designed profile and the final profile obtained by PGM. To reduce the form error of infrared ChG aspherical lens in the PGM process, a form error compensation model based on the random forest (RF) algorithm is proposed. The infrared ChG aspherical lens profile was first machined on an electroless nickel-phosphorus (Ni–P) plating to serve as the mold for PGM. After molding, the profile data of the lens was extracted, and a compensation model based on RF was constructed to optimize the model parameters using the evaluation parameters such as root mean square error (RMSE), coefficient of determination (R2), and out-of-bag (OOB). Finally, the generated compensated profile based on the compensation model was used for the compensation machining of the mold. Through this compensation approach, we have demonstrated a substantial 63.5 % reduction in the form error of the fabricated infrared ChG aspherical lens, decreasing the Peak-to-Valley (PV) value from 1.04 μm to 0.38 μm.

Enhanced electroless Ni-P plating quality on binderless tungsten carbide by atmospheric pressure plasma pretreatment

Precision glass molding (PGM) has been widely utilized in optical components production, during which binderless tungsten carbide (WC) is a popular mold material. Researchers have proposed the application of electroless nickel‑phosphorus (NiP) plating on WC molds, offering good surface finish, non-stick properties, and enhanced corrosion resistance, while typical NiP plating pretreatment is complex, time-consuming, carrying risks of surface damage and pollution. In this study, Atmospheric-pressure (AP) plasma surface processing has been proposed as an alternative pretreatment technique to enhance electroless NiP plating quality on binderless WC, contributing to the reduction of plating steps, time, smoothing of the plated NiP layer, and improvement in adhesion quality. The interaction mechanism between AP plasma and WC has been analyzed. The influence of AP plasma surface pretreatment on the surface quality of NiP plating has been investigated in detail. Surface characterization and adhesion test have been conducted to evaluate the effectiveness of AP plasma pretreatment method. Despite the fact the replication of substrate roughness exists in typical NiP plating process, the surface roughening and enhanced surface energy induced by AP plasma pretreatment can have a smoothing effect for the following electroless NiP plating process. The effectiveness of ICP AP plasma as an alternative pretreatment technique for high-quality electroless NiP plating on binderless WC has been validated.

Effect of Surface Activation on the Corrosion Resistance of a MAO/Ni-P Composite Coating on LZ91 Magnesium Alloy

BackgroundLZ91 Magnesium alloy with a dual-phase structure has improved mechanical properties and a low density of about 1.48 g/cm3 but their limited resistance to corrosion limits their application. Therefore, it is a great challenge to increase the stability of LZ91 alloys under corrosive factors and environments. MethodsThis study uses micro-arc oxidation (MAO) and an electroless nickel-phosphorus (Ni-P) plated composite film to increase the corrosion resistance of LZ91 magnesium alloy. Before electroless Ni-P plating, the MAO layers are activated by palladium catalysts at different pH values to produce composite coatings. SEM, EDS and Image J are used to determine the surface properties and elemental composition of the samples. The corrosion resistance is measured using a potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl solution. FindingsThe results show that the MAO coating is activated by an acid catalyst and the surface is obviously corroded. The electroless Ni-P plating grows into the MAO coating and the substrate corrodes. Therefore, corrosive medium (chloride ion) easily enter to the substrate and pitting corrosion occurred. On the contrary, activation by a neutral catalyst (pH=7) maintains the original structure of the MAO coating and provides a good bonding interface for the Ni-P coating. Form the potentiodynamic analysis can be finds that the corrosion potential for the neutral catalyst treated sample is -0.35V and the corrosion current density value is 1.77×10−6 A/cm2, so the corrosion characteristic become better than the acid catalyst treated samples. In terms of the long-term resistance after 48 h, EIS analysis shows that the resistance value remains at about 7.6×104 Ω•cm2. A composite coating that is compact and with excellent resistance to corrosion resistance is produced, which provides better protection for LZ91 magnesium alloys.

Thermomechanical performance enhancement of nickel-phosphorus mold by Ti-DLC coating

Glass molding technology is an ideal method for the mass production of the glass components, and electroless nickel-phosphorus (Ni-P) plating is widely used in the glass molding process as the mold material. However, the service life of the Ni-P mold reduces due to the diffusion of Ni atoms at high temperatures. To prolong its service life and protect the mold surface, a titanium-diamond-like carbon (Ti-DLC) coating is deposited on the Ni-P mold. This research studies the crystallization and diffusion of Ni atoms in both the Ni-P mold and the Ti-DLC coated Ni-P mold under a thermomechanical field. Additionally, the influence of Ti-DLC coating on the crystallization and diffusion behavior of single crystal Ni was investigated. The results show that the Ti-DLC coating protects the mold surface by suppressing the diffusion of Ni atoms rather than preventing the crystallization of Ni-P. The number of microbumps is used to describe the extent to which Ti-DLC coating improves the thermomechanical performance of Ni-P molds. The date shows the Ti-DLC coated Ni-P mold exhibit superior stability in 80 cycles of molding for no microbumps appearing on the surface. While the microbumps appear on the Ni-P mold surface after one-time molding, thus the thermomechanical performance of the Ni-P mold is further enhanced by Ti-DLC coating.

Stearic acid modified porous nickel-based coating on magnesium alloy AZ31 for high superhydrophobicity and corrosion resistance

In this work, a novel stearic acid modified nickel-based (NiSA) superhydrophobic composite coating with good anti-corrosion properties was prepared on magnesium alloy AZ31 surface through electroless nickel-phosphorus plating, electrodeposition of porous nickel, and decoration with stearic acid. Surface topography, chemical groups, and structural compositions of the NiSA coating were characterized through scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD), respectively. Adhesion of the NiSA coating was evaluated by a tape test method, and corresponding water contact angle (WCA) and water sliding angle (WSA) were tested by a contact angle meter. Results indicate that WCA value of the NiSA coating was 154.6° ± 3.7°, and WSA value was 5.9° ± 1.7°, indicating a high superhydrophobicity. Electrochemical impedance spectroscopy (EIS) and Tafel fitting reveal that the corrosion current density of the coating (jcorr = 1.41 × 10−8 A cm−2) was three orders of magnitude lower than that of the bare magnesium alloy, and the corresponding low-frequency impedance modulus (|Z|f = 0.01 Hz = 554.65 kΩ cm2) increased by three orders of magnitude, verifying high corrosion resistance. Moreover, all contact angles (CA) of common liquid stains in life were higher than 150°, indicating the good anti-fouling capability of the NiSA coating.

Characterization of electroless nickel-phosphorus plating for ultracold-neutron storage

Electroless nickel plating is an established industrial process that provides a robust and relatively low-cost coating suitable for transporting and storing ultracold neutrons (UCN). Using roughness measurements and UCN-storage experiments we characterized UCN guides made from polished aluminum or stainless-steel tubes plated by several vendors.All electroless nickel platings were similarly suited for UCN storage with an average loss probability per wall bounce of 2.8 ⋅ 10-4 to 4.1 ⋅ 10-4 for energies between 90neV and 190neV, or a ratio of imaginary to real Fermi potential η of 1.7 ⋅ 10-4 to 3.3 ⋅ 10-4. Measurements at different elevations indicate that the energy dependence of UCN losses is well described by the imaginary Fermi potential. Some special considerations are required to avoid an increase in surface roughness during the plating process and hence a reduction in UCN transmission. Increased roughness had only a minor impact on storage properties.Based on these findings we chose a vendor to plate the UCN-production vessel that will contain the superfluid-helium converter for the new TRIUMF UltraCold Advanced Neutron (TUCAN) source, achieving acceptable UCN-storage properties with η=3.5(5)⋅10-4.

Friction and Wear of Electroless Ni-P-CS Composite Coating

Carbon nanoparticles have excellent lubricating properties, however, they are less involved in metal protection. In this study, easily prepared candle soot was added to electroless nickel-phosphorus plating as a re-enforcement particle. Ball-disc friction and wear tests were conducted to evaluate the wear-resistance capabilities of the electroless Ni-P coating and Ni-P-CS (Candle Soot) composite coatings. The parameters for the friction coefficient, wear amount, and friction morphology of the Ni-P-CS composite coatings were studied after being heat-treated (300 °C, 400 °C, 500 °C, and 600 °C). The surface morphology and phase composition of the Ni-P-CS composite coatings after thermal treatment at various temperatures were also investigated. The results are as follows: heat treatment strengthens the local hardness of the Ni-P-CS composite coating but does not further enhance wear resistance. Compared with the Ni-P coating and the heat-treated Ni-P-CS composite coating, the Ni-P-CS composite coatings without heat treatment have a lower friction coefficient (0.35) and better wear resistance.

High-precision and high-efficiency fabrication of blazed grating by ultrasonic-assisted ultraprecision planing

Blazed gratings are optical components typically employed in modern optical engineering. To realize high-precision and high-efficiency fabrication of blazed gratings on reliable materials, an ultrasonic-assisted ultraprecision planing (UAUP) method using a round-nose diamond tool under elliptical vibration mode is proposed in this paper. High-phosphorus electroless nickel-phosphorus plating was adopted as the grating blank. The generation mechanism of the blazed grating texture was studied, and the relationship between the processing parameters and blazed grating characteristic dimensions was established. Through a combination of simulation and experiment, the theoretical and experimental results of the morphologies and optical performances of the blazed gratings were systematically compared and analyzed. The results show that the blazed grating configuration is an envelope of the diamond tool profile under ultrasonic vibration; the UAUP method has an extremely high machining efficiency owing to the high vibration frequency; and the blazed gratings fabricated using smaller vibration amplitudes exhibit high machining quality, good shape consistency, and favorable optical performance, thus verifying the feasibility of the UAUP method. • An ultrasonic-assisted ultraprecision planing (UAUP) method is proposed. • The grating configuration is precisely controlled by the processing parameters. • The machining efficiency of blazed gratings is extremely improved. • The fabricated blazed gratings exhibit favorable optical performance.

Analysis of Tool Wear and Counter Surface Roughness in the Flexible Abrasive Tool Finishing

This work uses the solvent casting method to fabricate an elastomeric tool with polyurethane as the base material and silicon carbide (SiC) as embedded abrasive particles. The distribution of abrasive particles and the pore structure in the fabricated tools are analyzed. The fabricated tools are porous in nature and have self-replenishing as well as self-lubrication properties. Aluminum 6061 alloy and electroless nickel-phosphorus plating having different initial roughness are selected as workpieces to study the wear mechanisms and loading of the flexible abrasive tool. The rotational speed of the tool, tool compression, and feed rate are fixed input process parameters. Total finishing time, sliding distance, and roughness are varied to obtain output responses. The workpiece material is also taken into account as a variable parameter in this study. These materials are classified as different counter surfaces as their surface roughness and mechanical properties vary. The finishing time and sliding distance for these counter surfaces differ in order to relate their effects on tool wear and loading. The nickel-plated surface shows a higher percentage reduction in surface roughness of 92% as compared to the aluminum surface, with a 62% reduction in surface roughness. The coefficient of friction, wear, and tool condition are analyzed to understand the mechanism of tool wear and tool loading. In this process, both two-body and three-body abrasions occur simultaneously and continuously.

The effect of fluoride on the formation of an electroless Ni–P plating film on MAO-coated AZ31B magnesium alloy

This study adds fluoride to the electroless nickel-phosphorus (Ni–P) plating solution to prevent the deterioration of MAO-coated AZ31B Magnesium alloy after contact with an electroless plating bath. During the electroless Ni–P plating process, fluoride reacts with Ni2+ ions and the MAO coating to form interphases (NaMgF3), which exhibit good bonding and corrosion resistance. NaMgF3 buffers H+ ions formed from the initiation of Ni–P deposition, preventing the interface of materials from damaging the MAO coating with H+ ions. As immersion time increases, nickel is scattered over the coating.The fundamental data for MAO/Ni–P coated AZ31B Mg alloy determines whether there is fluoride in the electroless Ni–P plating solution. The results show that the coating for a fluoride-containing solution is more resistant to corrosion than those in fluoride-free solution. The compositions, structure and morphology of the MAO/Ni–P coatings that formed for different working parameters are determined using energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The corrosion resistance of the MAO/Ni–P coatings is calculated in a 3.5 wt.% NaCl solution using a potentiodynamic polarization test, electrochemical impedance spectroscopy (EIS) and a salt spray test (SST).

Iodide-induced galvanic replacement of nickel film on copper as activator for electroless nickel-phosphorus plating

Galvanic replacement provides a convenient route to synthesize metallic films and nanostructures. However, metals commonly reduce more noble metal ions. In this work, nickel film was deposited on copper through an iodide-assisted galvanic replacement method. It was found copper had a lower electrode potential than nickel in high concentration of iodide solution, so nickel film could be obtained through the unusual galvanic replacement. The experimental results revealed increasing iodide concentration was conducive to the galvanic replacement rate between copper and nickel ions, and complete nickel film could be obtained in solution with 1200 g·L−1 sodium iodide in 10 min. The as-prepared nickel film showed good activation ability for electroless nickel-phosphorus plating, for the nickel-phosphorus coatings obtained on the nickel and traditional palladium films possessed similar morphology, structure and corrosion resistance.

Fabrication of efficient and robust Fe0/Ni2P/CC composite and the employment for electrochemical reduction of nitrate

The process of electrochemical nitrate reduction behaving the merits of sufficient efficacy and environmental benignity has attracted immense interest for the nitrate (NO3-) disposal. However, the practical application of this technique is seriously restricted due to the defects of generating by-products (such as ammonium and nitrite), and the presence of total nitrogen (TN) with a high concentration. In this work, a novel catalyst composite (Fe0/Ni2P/CC) was fabricated via the combined method involving liquid-phase reduction, electroless nickel-phosphorus plating and phosphation processes. The crystal structure, morphology, and chemical component of the obtained composite were characterized. The influences of operating parameters (pH value, current density, initial nitrate-N concentration and coexisting substances) on the NO3- reduction were assessed. At the optimized conditions, the synthesized Fe0/Ni2P/CC composite displays the fascinating performances in NO3- conversion (89.81%), N2 selectivity (95.55%) and tested endurance, comparing with other three samples (i.e. Fe0 +Ni2P/CC, pure HER and pure Fe0). For the disposal for simulated effluent of municipal wastewater treatment plant effluent, this composite exhibits a superb NO3- conversion of 89.81%, and the concentration of TN (1.92 mg L−1) is lower than the threshold limit (2 mg L−1) of five-level standard for surface water of China. It is noteworthy that the Fe0/Ni2P/CC composite has an excellent durability (< 5% decay after 20 h reduction test), and the spent sample can be employed for the decoloring of methyl orange via the chemical advanced oxidation process (95% for decolorization efficiency).

The Effect of Polytetrafluoroethylene (PTFE) Particles on Microstructural and Tribological Properties of Electroless Ni-P+PTFE Duplex Coatings Developed for Geothermal Applications

The selection of electroless nickel-phosphorus plating (ENP) has been inclined towards their properties and advantages with complex geometry applications. These properties include coating uniformity, low surface roughness, low wettability, high hardness, lubricity, and corrosion- and wear-resistance. Materials used in geothermal environments are exposed to harsh conditions such as high loads, temperature, and corrosive fluids, causing corrosion, scaling, erosion and wear of components. To improve the corrosion- and wear-resistance and anti-scaling properties of materials for geothermal environment, a ENP duplex coating with PTFE nanoparticles was developed and deposited on mild steel within the H2020 EU Geo-Coat project. ENP thin adhesive layer and ENP+PTFE top functional layer form the duplex structure of the coating. The objective of this study was to test the mechanical and tribological properties of the developed ENP-PTFE coatings with varying PTFE content. The microstructural, mechanical and tribological properties of the as-deposited coating with increasing PTFE content in the top functional layer in the order: ENP1, ENP2 and ENP3 were evaluated. The results showed maximum wear protection of the substrates at the lowest load; however, increasing load and sliding cycles increased the wear rates, and 79% increased lubrication was recorded for the ENP2 duplex coating. The wear performance of ENP3 greatly improved with a wear resistance of 8.3 × 104 m/mm3 compared to 6.9 × 104 m/mm3 for ENP2 and 2.1 × 104 m/mm3 for ENP1. The results are applicable in developing low friction, hydrophobic or wear-resistive surfaces for geothermal application.

Recovery of Phosphorus from Waste Solution of Electroless Nickel-Phosphorus Plating

We attempted to recover phosphorus species from a waste plating solution of electroless nickel-phosphorus plating. With the aim of increasing the recovery yield by oxidizing phosphite to phosphate efficiently, we examined ozonation of a model plating solution by supplying ozonecontaining oxygen gas to the solution employing an aerated mixing vessel. As a result of the measurements of the transient changes in the concentrations of the phosphorus species and dissolved ozone in the solution, we confirmed the effect of the organic additives contained in the plating solution on the ozonation efficiency. Calcium chloride was subsequently added to the ozone-treated solution to precipitate the phosphate as calcium hydrogen phosphate, which was poorly soluble to water. At this moment, the recovery yield of the phosphorus from the model waste plating solution was greater than 86%.

Kinetic Modelling of Electroless Nickel-Phosphorus Plating under High Pressure.

In electroless nickel–phosphorus plating (ENPP), growth of the plated layer under high pressure was found to be faster than under ambient pressure. To quantitatively elucidate the effect of high pressure on the mechanism of the ENPP reaction, we propose a kinetic model that takes into account both mass transfer and reaction of the chemical species present in the plating solution. We solved the mass balance equations between the chemical species to calculate the transient changes in the thickness of the plated layer as well as the concentrations of the chemical species in the plating solution. By fitting the calculated results to the experimentally acquired results based on the nonlinear least square method, we determined such parameters as the film mass transfer coefficient, the adsorption constants, and the reaction rate constants of the chemical species in the model. As a result, we found that the film mass transfer coefficient under high pressure was greater than that under ambient pressure and revealed the dependence of the coefficient on pressure. The transient changes in the concentrations of the chemical species in the plating solution that we calculated based on the kinetic model employing our estimated parameters closely modeled the experimental results with the determination coefficients being mostly over 99%.

Study on corrosion behavior of TWIP steel and properties of surface electroless Ni-P coatings

In this study, the corrosion behavior and corrosion resistance of TWIP (Twinning Induced Plasticity) steels in the industrial atmospheric environment were studied by dry-wet cycle immersion test and electrochemical experiments. The results showed that the corrosion rates of TWIP steel gradually decreased with the increase of corrosion time. A layer of corrosion products was formed on the surface of TWIP steel during alternating immersion accelerated corrosion process, whose main components were Fe3O4 and α-FeOOH. With the prolongation of corrosion time, the rust layer on the surface of TWIP steel had a certain protective effect on the steel matrix. The adherent and defect-free electroless nickel–phosphorus (Ni-P) coatings were prepared on TWIP steels. Electrochemical test results showed the corrosion current density of the coating was about six times lower than that of TWIP steel substrate, indicating that the coating effectively improved corrosion resistance of TWIP steel and protected the steel substrate from erosion of corrosive ions. Additionally, the surface microhardness of TWIP steel was significantly increased after electroless Ni-P plating treatment.

Effect of Processing Parameters on the Thermal and Electrical Properties of Electroless Nickel-Phosphorus Plated Carbon Fiber Heating Elements

Carbon fibers (CFs) were plated with nickel-phosphorus (Ni-P) using an electroless plating process. The effects of the process parameters such as heat treatment temperature, heat treatment time, and the pH of the plating bath on electroless Ni-P plating were investigated. The structure, elemental composition, and thermal and electrical properties of Ni-P plated CFs (MCF) were characterized by X-ray diffraction (XRD), a four-probe volume resistivity tester, and an infrared thermal imaging camera, respectively. The XRD indicated the presence of amorphous and crystalline phases of Ni and Ni-P. The MCF were able to perform at high temperatures because of their higher thermal conductivity. A heat treatment temperature of 300 °C, a heat treatment time of 4 h, and a pH of 8.5 were found to be optimum for obtaining MCF with desirable thermal and electrical properties.

Electroless nickel–phosphorus plating on WC–Co powders using HVOF feedstock

ABSTRACTIn this study, electroless nickel–phosphorus plating was optimised for WC–Co powder using different bath loads and then subjected to a high-velocity oxygen fuel process. The produced Ni–P-coated WC–12Co powders were subsequently used as HVOF feedstock materials. Based on the SEM results, an increase in the bath load resulted in a decrease in the thickness of the Ni–P coating formed on the WC–12Co powders. Moreover, applying the HVOF process led to a lower porosity and roughness and a higher thickness of nickel coating, whereas applying a suitable thickness of this coating can prevent the destructive W2C phase. Finally, a bath load of 16 g L–1 was determined as the optimum value to achieve a proper thickness of the Ni–P, extremely low porosity (0.3%), good surface roughness (5 μm), and high microhardness (1112 Hv) in the produced coating.

Electroless Deposition of Composite Materials: From Fundamental Mechanisms to Applications

Electroless nickel phosphorus (Ni−P) plating is an autocatalytic reduction process that has been used for various engineering applications. High phosphorus metallic matrix materials produced by electroless deposition are examined to exploit the good corrosion behavior of such coatings and the high mechanical properties of the composites. In order to obtain the desired properties, it is important to deeply understand the deposition mechanism and its influence on the final characteristics of the layer. The kinetic mechanism of the electroless deposition of NiP matrix from hypophosphite solutions is investigated from first principles with the intent of determining a set of elementary reactions that could effectively identify the most relevant steps of this complex process. The outcome of the computational approach is discussed in terms of experimental results obtained by electrochemical methods and surface analysis techniques [1,2]. The interaction of Ni++ and H2PO2 - with the Ni surface was studied using Ni clusters of different sizes (from 4 to 12 atoms), introducing solvation in water through the implicit polarizable continuum model. Though several theories were proposed to describe this key step in the literature, our search was guided by the original insight published several years ago [3], according to which the reduction of Ni++ requires the formation of an intermediate species containing the NiOH group. Such species would then take active part in the transfer of the OH group to H2PO2 -, thus favoring its oxidation to H2PO3-. In order to understand completely the adsorption phenomena on the electrode surface during the electroless deposition process, in situ-Raman analyses were performed. The effect of each complexing agent dissolved into electroless NiP bath on complexes adsorbed on the electrode surface and the comparison with the DFT computational analysis will be presented, highlighting the effect of additives, e.g. tungsten salts, added to the electrolyte to modify the properties of the matrix. A tool based on computational fluid dynamics CFD simulation for the co-deposition of the dispersed phase is also presented, showing the correlation between particles’ load in the bath and the amount of co-deposited particles as a function of hydrodynamic conditions. The results are discussed in light of the theoretical models proposed to describe the co-deposition processes. Following the theoretical description, composite coatings are produced and characterized in terms of particles content and distribution, morphology and mechanical properties. Erosion resistance is specifically investigated with respect to sand particles fluxes, discussing the optimal combination between the metallic matrix and the dispersed phase. Corrosion behavior is presented both in electrochemical tests and in accelerated tests in salt spray chamber. The effect of the applied thermal treatment to modify the mechanical properties is investigated and discussed as a function of the dispersed phase. [1] P.L. Cavallotti, L. Magagnin, Influence of added elements on ACD electroless NiP, ECS Transactions, 50 (53) 1-8 (2013). [2] P.L. Cavallotti, L. Magagnin, C. Cavallotti, Influence of added elements on autocatalytic chemical deposition electroless NiP, Electrochim. Acta (2013), http://dx.doi.org/10.1016/j.electacta.2013.09.083. [3] P.L. Cavallotti, G. Salvago, Electrochimica Metallorum III, 239 (1968)

高圧力下での無電解ニッケル–リンめっき

高圧力下での無電解ニッケル–リンめっき