Ni-P Layer Research Articles

Tribocorrosion behavior of electroless Ni-P/Ni-B duplex coating on AA7075 aluminum alloy

Purpose This paper aims to investigate the structural, corrosion and the study of tribocorrosion features of the AA7075 aluminum alloy with and without the application of electroless Ni-P/Ni-B duplex coating with a thickness of approximately 40 microns. Design/methodology/approach Surface characterization of the samples was made by structural surveys (light optic microscope, scanning electron microscopic examinations and X-ray diffraction analyses), hardness measurements, corrosion and tribocorrosion tests. Findings Results of the experiments showed that upper Ni-B coating deposited on the surface of first Ni-P layer by duplex treatment caused remarkable increment in the hardness, corrosion resistance and tribocorrosion performance as compared to the AA7075 aluminum alloy. Originality/value This study can be a practical reference and offers insight into the effects of duplex treating on the increase of hardness, corrosion and tribocorrosion performance.

Electroless plating on the surface of kapok fibres: analysis of an effective palladium-free nickel salt activation process

ABSTRACTA two-step, palladium-free, nickel salt activation process was tested on kapok fibres (KF). The results showed that the ratio of the concentration of hydrogen ions to the concentration of hydroxide ions ([H+]/[OH−]) in the activation bath needs to be controlled within a range to achieve an optimal outcome. The final amount of deposited active Ni is not only dictated by [NiSO4·6H2O] but also dependent on the concentration of the reducing agent, [NaBH4], whose proper value is complicated by its self-decomposition reaction that can be catalysed by the active Ni and H+ ions. The concentration of NiSO4 employed needs to be capped to attain reasonable mass density and high electrical conductivity as required by light-weight electromagnetic interference shielding materials. An effective activation bath was formulated and experimentally confirmed to successfully initiate and sustain such an electroless plating process and a compact, uniform and amorphous Ni-P layer was formed on the KF surface.

Effects of Bath Composition and P Contents on the Defects of NiP Layer in Electroless Nickel Immersion Gold Process.

Electroless nickel immersion gold (ENIG) has been widely used for surface finishing in PCB industry, however surface defects are sometimes found during PCB soldering process. These defects cause failures in soldering on PCB and consequently cause poor safety probability of products. The formation mechanism of the defects in the NiP layer was investigated. Three parameters on the black pads were analyzed. First, morphology was analyzed with changing metal turn over (MTO) numbers. Second, pH of Ni solution was changed in the ENIG process. Third, stress of NiP layers was analyzed at different pH. The relationship between each defect and P contents was analyzed. High open circuit voltage (OCV) can cause the poor surface morphologies as well as the defects. High and large difference of P contents in NiP layer can act the important role in the formation of black pads. The high tensile stress can also be another factor of the formation of black pads.

Structural Analysis of Thin Ni-P Layers

The deposition mechanism by autocatalytic reduction method is a chemical one, which does not lead to structures as shown in the Ni-P balance diagram. In the experiments of the present work, Ni-P layers were made deposited on thin steel strip with low carbon content. By optical microscopy and scanning electron microscopy by (SEM) it was analyzed the appearance and surface morphology of the deposited layers depending on the content of phosphorus and working parameters (temperature, pH, stirring speed). The layer structure was analyzed in the cross section and on the break surface. The analysis results show that thin coatings of Ni-P have a surface topography that follows faithfully the steel support. Depending on the content of phosphorus, on the layer surface of low phosphorus content, spherical particles of different sizes can be seen while high and average phosphorus content coatings feature a smooth surface with nanometer-sized grains. Analysis of the cut-off /break section of the Ni-P layer structure, show a more or less porous structure depending on the stirring speed and pH level.

Thermal shock behavior of YSZ thermal barrier coatings with a Ni-P/Al/Ni-P sandwich interlayer on AZ91D magnesium alloy substrate at 400 °C

Thermal barrier coatings (TBCs) consisting of yttria-stabilized zirconia (YSZ) as top coat and NiCrAlY as bond coat were deposited on AZ91D magnesium alloy substrate by atmospheric plasma spraying (APS). In order to improve the stability and prolong the thermal shock life of TBCs, a Ni-P/Al/Ni-P sandwich interlayer between the AZ91D magnesium alloy substrate and the NiCrAlY bond coat was fabricated by electroless plating for Ni-P layer and APS for Al layer. The thermal shock behavior of the YSZ TBCs with the Ni-P/Al/Ni-P sandwich interlayer quenched in water at 400 °C was investigated in detail. The results showed that the thermal shock life of YSZ TBCs with the Ni-P/Al/Ni-P interlayer on the AZ91D substrate was about 226 cycles. The failure of YSZ TBCs in thermal shock test was mainly induced by the corrosion of AZ91D substrate. The results of polarization tests and electrochemical impedance spectroscopy showed that the Ni-P/Al/Ni-P interlayer had better corrosion protection for the magnesium alloy substrate than the Ni-P interlayer, which thus enhanced the thermal shock life nearly two times as compared to that of YSZ TBCs with the Ni-P interlayer.

Fabrication and characterization of TiB2-TiC-Co wear-resistant coatings on AZ91D magnesium alloy

TiB2-TiC-Co cermet coatings were fabricated on AZ91D Mg alloy substrate by atmospheric plasma spraying (APS) using the powders produced by self-propagating high-temperature synthesis (SHS) from Co-Ti-B4C system. In order to improve the bonding stability between cermet coating and substrate, the interlayer of Ni-P/NiCrAlY was prepared by the combination of electroless and APS methods. Microstructure and phase composition of the SHS products and coatings were investigated. Correlation between microstructure and wear properties of the cermet coatings was discussed. The results showed that the interlayer prevented Mg alloy substrate from oxidation or ablation, and bonded tightly to both the substrate and cermet coating. The tensile failure of triple-layer coatings was mainly located at the interface between the NiCrAlY layer and NiP layer, with the bonding strength of 21.4 ± 3.2 MPa. The two cermet coatings with different grain sizes of TiB2-TiC provided good wear resistance for substrates owing to their high hardness of about 1059 and 1018 HV, respectively. Moreover, the cermet coating composed of finer ceramic particles exhibited a more compact and uniform structure, which led to a significant reduction in wear rate and friction coefficient. The wear mechanisms of cermet coatings against alumina-ball counterpart were a mix of exfoliation of hard phases and abrasive wear by micro-cutting.

Significant Inhibition of IMCs Growth between an Electroless Ni-W-P Metallization and SAC305 Solder During Soldering and Aging

The formation and growth behavior of intermetallic compound (IMC) layers after introducing an electroless Ni-W-P metallization into the Sn-3.0Ag-0.5Cu (SAC305) solder joint during soldering and aging were investigated. The soldering was performed at 250 °C for 10 min, followed by air cooling and aging treatment at 150 °C up to 15 days. The results show that the scallop-like Cu6Sn5 IMC layer and planar-like Cu3Sn formed between solder and Cu substrate during soldering and aging. The Ni3P and (Ni,Cu)3Sn4 compounds were formed between electroless Ni-W-P layer and solder, and Cu substrate was not damaged and kept a smooth interface. When the isothermal aging treatment was applied, the total thickness of IMCs which formed at the SAC305/Cu and SAC305/Ni-W-P/Cu interface increased with increasing aging time. Kirkendall voids emerged at the Cu3Sn and the Ni3P layers, but the voids emerged at the Ni3P layer in the form of crack. The amount of Kirkendall voids increased and the crack elongated with increasing aging time. The Cu6Sn5 and (Ni,Cu)3Sn4 grains grew by merging adjacent grains. In the process of growth, the growing interfacial compounds filled the free space, and new columnar dendrite grain of (Ni,Cu)3Sn4 constantly generated during aging treatment. After 15 days aging, the Ni-W-P barrier layer was still remained, which indicated that the Ni-W-P layer can be a good barrier layer between the solder alloys and Cu substrate.

Preparation and Performance of Electroless Nickel on HVOF (High-Velocity Oxygen Fuel) Sprayed Inconel 625 Nickel Coating for Corrosion Protection Applications

High Velocity Oxy-Fuel (HVOF) spraying is one of the preferred surface engineering technologies that can offer advantages such as user-friendliness and cost-efficiency in mass production of coatings for various applications. While the main applications of the HVOF process are related to wear, corrosion resistance can be one of the important desired features of the surface engineering process. However, the porosity of HVOF sprayed coatings is usually a problem when coatings are used in corrosion applications. Low carbon steel substrates were High-Velocity Oxygen Fuel (HVOF) sprayed with Inconel 625 and then coated with a thin film of electroless nickel (electroless nickel plating). Reference sample without electroless nickel was sprayed at the same time. Characterization of the coatings was made by X-Ray diffraction analyses, microstructural surveys, cross-section and corrosion tests. Results showed that sequential application of HVOF spraying and electroless coating processes provided the multi-layered coating consisting of an inner inconel 625 based layer and an outer Ni-P layer. Electroless Ni-P also caused the remarkable increasing in the corrossion resistance as compared to the as-HVOF sprayed state.

Химическое осаждение гибких светоотражающих слоев Ni-P на полиэтилентерефталатной подложке

Разработан способ химического осаждения из растворов слоев Ni-P на полиэфирных подложках. Исследованы состав, микроструктура и физико-механические характеристики электропроводного светоотражающего металлопокрытия на поверхности полиэфирных тканей.

Growth behavior of IMCs layer of the Sn–35Bi–1Ag on Cu, Ni–P/Cu and Ni–Co–P/Cu substrates during aging

In this work, the interfacial reactions and IMC growth of the Sn–35Bi–1Ag on Cu, Ni–P/Cu and Ni–Co–P/Cu were studied during reflowing at 220 °C for 10 min and solid–state treatment at 150 °C with various aging times. For the solder joints of Sn–35Bi–1Ag/Cu, Cu6Sn5 IMC was formed at the interfacial layer after soldering, while Cu3Sn appeared after aging treatment. In the case of the electroless Ni–P plating of Cu, the IMC formed at the interface during isothermal aging was mainly Ni3Sn4 and a small amount of P-rich Ni (Ni3P) layer between the Ni3Sn4 IMC and the electroless Ni–P plating layer. In the case of the electroless Ni–Co–P plating of Cu, the IMC formed at the interface during isothermal aging was mainly (Ni, Co)3Sn4 and a small amount of P-rich Ni ((Ni, Co)3P) layer between (Ni, Co)3Sn4 IMC and the electroless Ni–Co–P plating layer. The addition of Co atoms could effectively inhibit the IMC growth rate, which inducing a lower growth rate of (Ni, Co)3Sn4 than that of Ni3Sn4. The thickness of Ni3P and (Ni, Co)3P layer reached about 2.31 µm and 1.25 µm after aging for 360 h, respectively. Also, the growth kinetics of the Ni3P and (Ni, Co)3P layer was found to be a diffusion–controlled process, which followed a parabolic relationship in the thickness increase. During the aging, the consumption of the electroless Ni–Co–P plating layer was greatly reduced compared with that of the electroless Ni–P plating layer. Moreover, there were no voids observed in the electroless Ni–Co–P plating layer while some defects formed in that of the electroless Ni–P plating layer. The electroless Ni–Co–P plating layer will be a good diffusion barrier for the lead-free soldering.

Corrosion resistance of nickel-coated SiCp/Al composites in 0.05 M NaCl solution

The SiCp/Al composites was modified by electroless nickel plating, the corrosion behavior of Ni-coated SiCp/Al composites in 0.05 M NaCl solution was investigated by situ electrochemical techniques. The surface properties of the Ni-coated SiCp/Al composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectrometer (EDS). The results showed that: The Ni-P layer is the most uniform with a thickness of 15 μm after electroless nickel plating for 60 min; Soak in 0.05 M NaCl solution, Ni-coated SiCp/Al composites exhibits higher corrosion potential and impedance values than non-coated SiCp/Al composite, showed that a greater corrosion resistance of Ni-coated SiCp/Al composite, and the corrosion resistance of SiCp/Al composite is the best after 60 min nickel plating. The Scanning Electrochemical Microscopy (SECM) measurements showed that the formation of the corrosion-resistant passive film in the Ni-coated SiCp/Al composites are easier, and the main corrosion mechanism of composites is local corrosion. The nickel phosphorus compound is easily produced on the surface of Ni-coated SiCp/Al composites after polarizing 1 h, which inhibits the corrosion of the composite. Thus, the Ni-coated SiCp/Al composite has greater corrosion resistance in a chloride-containing environment than the SiCp/Al composite.

Influence of Interfacial Intermetallic Growth on the Mechanical Properties of Sn-37Pb Solder Joints under Extreme Temperature Thermal Shock

Solder joints in thermally uncontrolled microelectronic assemblies have to be exposed to extreme temperature environments during deep space exploration. In this study, extreme temperature thermal shock test from −196 °C to 150 °C was performed on quad flat package (QFP) assembled with Sn-37Pb solder joints to investigate the evolution and growth behavior of interfacial intermetallic compounds (IMCs) and their effect on the pull strength and fracture behavior of Sn-37Pb solder joints under extreme temperature environment. Both the scallop-type (Cu, Ni)6Sn5 IMCs at the Cu lead side and the needle-type (Ni, Cu)3Sn4 IMCs at the Ni-P layer side changed to plane-type IMCs during extreme temperature thermal shock. A thin layer of Cu3Sn IMCs was formed between the Cu lead and (Cu, Ni)6Sn5 IMC layer after 150 cycles. The growth of the interfacial IMCs at the lead side and the Ni-P layer side was dominated by bulk diffusion and grain-boundary diffusion, respectively. The pull strength was reduced about 31.54% after 300 cycles. With increasing thermal shock cycles, the fracture mechanism changed from ductile fracture to mixed ductile–brittle fracture, which can be attributed to the thickening of the interfacial IMCs, and the stress concentration near the interface caused by interfacial IMC growth.

Infiltration brazed core-shell WC@NiP/NiCrBSi composite cladding

In this study, a novel Ni-P-coated WC/NiCrBSi composite cladding was prepared on a carbon steel substrate through high-temperature vacuum brazing technique with the aim of improving the wear properties of the surface. In order to improve the wettability of WC particles by a liquid phase (NiCrBSi alloy), Ni-P layer was deposited on carbide particles by electroless plating. This layer assisted to fabricate a thick coating with very low porosity, improving adhesion strength between ceramic particles and the matrix. The morphology, crystal structure and microstructure of coated carbides and the resultant composite cladding were characterized by field emission scanning electron microscopy (FESEM) equipped with energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) analysis. Thin electroless plated Ni-P shell with a thickness about 50–150 nm, were coated on WC particles. In the claddings, a uniform and homogenous distribution of WC particles in Ni-based matrix was observed. The pin on disk wear test was carried out to investigate the wear behavior of the fabricated cladding reinforced with and without Ni-P coated WC particles. The results indicated that the resistance against crack initiation and propagation significantly improved by using Ni-P layer in the sintered cladding. This cladding exhibited very low wear weight loss than conventional brazed cladding.

Effect of Heat Treatment of AZ91 Magnesium Alloy on the Electroless Ni-P Deposition

Magnesium alloys are excellent choice for automobile, aerospace, and computer components owing to their light weight, unique physical and mechanical properties. However, poor corrosion resistance has restricted their applications in aggressive environments. The surface coating is one of the viable options to reduce the susceptibility of magnesium alloys to corrosion. The present study focuses on the effect of heat treatment of AZ91 magnesium alloy, for different durations at 400 °C, prior to electroless Ni-P deposition on corrosion resistance. The microstructure and elemental analysis of the heat-treated specimens are performed using SEM and EDS techniques respectively. It is observed that the duration of heat treatment has a significant effect on the surface morphology and microstructure of the alloy. The precipitates in the cast alloy (enriched with Mg and Al) fragmented and the transformed into a new Al and Zn rich phase, after 12 h heat treatment. The dissolution of precipitates, however, observed on heating further to 24 h and exhibited relatively a lesser corrosion current density. The dense electroless Ni-P deposition is formed on the alloy heat treated for 24 h. The corrosion behavior of the single Ni-P layer on the heat treated (for 12 h) and untreated alloy show a marked deterioration, as investigated by the anodic polarization and electrochemical impedance spectroscopy (EIS) techniques. Relatively a better corrosion performance is seen for the double-layer Ni-P deposition. The duplex layer coatings on the as cast and heat treated for 24 h at 400 °C substrates showed an improved corrosion resistance compared to that on the 12 h heat treated substrate.

THE EFFECT OF SURFACE ROUGHNESS AND STIRRING SPEED ON THE COATING CHARACTERISTICS OF MARTENSITIC ELECTROLESS Ni-P

Coating process of martensitic stainless steel 420 (SS 420) as the base material component of the steam turbine blade component uses an Electroless Ni-P coating process. This process is one of the solution coatingsthat applied to stainless steel as a substrate to improve corrosion resistance.The goal of this research is to get an idea and information about the effect of surface roughness and stirring speed on the characteristics of Electroless Ni-P layer. Experimental parameters in this research were variations of 0.044 μm, 0.056 μm, 0.101 μm, and 0.164 μm surface roughness and variations of 4.9 rpm, 11.3 rpm, and 21.3 rpm stirring speed. Results showed that the surface roughness and low stiring speed causes the grain distribution becomes more uniform, whichis shown by Scanning Electron Microscopy (SEM) examination. Adhesion layer also increases along with increasing levels of surface roughness. The highest value of adhesion was 1.9 MPa at 0.164 μm and the lowest value of adhesion was 0.8 MPa at 0,044 μm.

The influence of thickness of Ni-P layers produced on AW-7075 aluminum alloy on their adhesion and mechanical properties

The article presents the results of mechanical tests of Ni-P layers deposited by the chemical reduction method on the AW-7075 aluminum alloy. The effect of layer thickness on hardness and microhardness of Vickers, which was determined by the DSI method, and their adhesion to the substrate by scratch method were investigated. The morphology was obtained using light microscopy and the topography of the examined layers using a contact profilometer. Different thicknesses were used to determine their effect on adhesion of the leyers to AW-7075 alloy. The results allowed to state that Ni-P layers of higher thickness are characterized by higher hardness and Young's modulus values than thinner Ni-P layers, and also show better adhesion to the AW-7075 alloy.

Direct growth of ZnO nanostructures on the Zn electroplated mild steel to create the surface roughness and improve the corrosion protection of the electroless Ni-P coating

The disadvantages of some methods applied to deposit or grow ZnO structures led us to conduct experiments on the direct growth of the ZnO through the new and highly applicable procedure. For this purpose, the mild steel surface after the activation was coated with a thin layer of Zn using the electroplating method. This technique eliminated the need of the pure Zn foil as a relatively expensive substrate. The conventional and sonochemical hot water treatment of as-synthesized Zn crystals for the conversion to the ZnO phases offered economic benefits because there was no need for the special pretreatment of the surface before thermal oxidation. As a practical application, as-grown ZnO structures (as the sublayer) were covered with the electroless Ni-P layer and the improvement in corrosion protection of binary Ni-P coatings with and without sublayer of ZnO was studied by the electrochemical method.

Microstructure and thermal decomposition property of Ni-P/Cr2N composite powder by electroless plating

Cr2N is the most promising blowing agent for the preparation of steel foam using melt foaming method. In this work, to obtain a blowing agent with suitable density and gas decomposition characteristics for steel melt foaming, Ni-P/Cr2N composite powder was prepared by electroless plating. The surface morphology, phase, coating thickness, density and decomposition characteristics of Ni-P/Cr2N composite powder were analyzed. The results indicate that the surface of Ni-P/Cr2N composite coating powder is covered by the high nickel and low phosphorus layer which has a dense and uniform cell structure. The decomposition rate of the Ni-P/Cr2N composite powder is 7.46 mW/mg slower than that of the uncoated Cr2N powder at 1107.4 °C. When the plating time is 30 min, the thickness of Ni-P layer reaches 2.86 μm, the density of the Ni-P/Cr2N composite powder is 7.45 g/cm3, and maximal decomposition rate temperature reaches 1500 °C. These findings suggested that Ni-P/Cr2N composite powder meets the requirements of decomposition temperature and density of the blowing agent used to produce steel foam with a uniform pore structure by the melt foaming method.

Electroless deposition and characterization of a double-layered Ni-B/Ni-P coating on AZ91D Mg alloy from eco-friendly fluoride-free baths

Electroless Ni deposition has attracted much interest in surface modification of Mg alloy owing to its good performance, especially in corrosion inhibition. In this work, an electroless double-layered Ni-B/Ni-P coating on AZ91D Mg alloy was fabricated successfully by plating of a Ni-B layer as primer and a Ni-P layer as outer layer from eco-friendly fluoride-free plating baths. The morphology, composition, and phase structure of the coatings were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS), and X-ray diffractometer (XRD), respectively. Several different electrochemical techniques such as linear sweep voltammetry, chronoamperometry, and electrochemical impedance spectroscopies (EIS) were used to analyze the deposition process and demonstrate the enhancement of corrosion inhibition of the Ni-B/Ni-P duplex coating. In addition, compared with Mg alloy and a single Ni-P coating, the new-designed duplex coating also exhibits a remarkable enhancement in micro-hardness.

Ni-P/Zn-Ni compositionally modulated multilayer coatings – Part 1: Electrodeposition and growth mechanism, composition, morphology, roughness and structure

The Ni-P/Zn-Ni compositionally modulated multilayer coatings CMMCs were electrodeposited from a single bath by switching the cathodic current density. The composition, surface morphology, roughness, layers growth pattern as well as the phase structure of deposits were extensively studied via SEM, EDS, AFM and XRD analysis. Effects of bath ingredients on the electrodeposition behavior were analyzed through cathodic linear sweep voltammetry. Although the concentration of Zn2+ in bath was 13 times higher than Ni2+, the Zn-Ni deposition potential was much nearer to Ni deposition potential rather than that of Zn. Addition of NaH2PO2 to the Ni deposition bath considerably raised the current density and shifted the crystallization potential of Ni to more nobble values. Codeposition of P with Zn-Ni alloy lead to crack formation in the monolayer that was deposited in 60 mA/cm2. However, the cracks were not observed in the Zn-Ni layers of multilayers. Zn-Ni layers in CMMCs exhibited a three-dimensional pattern of growth while that of Ni-P layers was two-dimensional. Also, the Ni-P deposits tends to fill the discontinuities in Zn-Ni layers and performed leveling properties and lowered the surface roughness of Zn-Ni layers and CMMCs. Structural analysis demonstrated that Ni-P layers were amorphous and the Zn-Ni layers exhibited crystallite phase of Zn11Ni2. Thus, the Ni-P/Zn-Ni CMMCs comprised of alternate layers of amorphous Ni-P and nanocrystalline Zn Ni.