Ni-P Particles Research Articles

Tribological Behaviors of Ni-P Coatings on PEO-Treated AA1050 Alloy

Tribological behaviors of the plasma electrolytic oxidation (PEO)-treated Al1050 alloy surface without and with Ni-P deposits was examined by analyzing of the width of abrasion groove, weight loss, friction coefficient and composition at the wear track after a 100 m ball-on-disc test. The surface color, surface and cross-sectional morphologies and surface roughness (Ra) were also investigated to explain different wear behaviors of PEO films without and with Ni-P deposit. After the 100 m ball-on-disc test, a circular abrasion groove with relatively large width and shallow depth was formed when Ni-P particles cover the top surface of PEO films, but a relatively narrow and deep circular abrasion groove was formed on the Ni-P layer-covered PEO film surface. Iron was only detected at the wear track of 5 and 10 μm PEO films without Ni-P deposit, suggesting that the steel ball is worn out by the PEO films but not by the Ni-P deposit. An extremely large amount of weight loss was obtained from the Ni-P layer-covered PEO film surface, which could be related to the high density and low hardness of the Ni-P layer.

Microstructure, composition and formation mechanism of ultra-black surfaces on the electrodeposited nickel-phosphorous coatings

Light absorbing materials are of practical importance in the production of optical devices in aerospace technology. A new method of light absorbing coatings preparation on the basis of electrodeposited nickel-phosphorus coatings has been proposed. Modification of the electrolyte for nickel-phosphorus plating by the addition of saccharine allowed preparing an ultrablack surface with a reflectance coefficient less than 0.5%. Chemical composition of both surfaces has been studied using X-ray photoelectron spectroscopy. The mechanism of their formation has been proposed. It has been found that etching in nitric acid leads to the partial oxidation of both surfaces with the formation of needle like microstructure.It also results in surface enrichment with phosphorus and formation of nickel phosphides particles of the variable composition. Products of the coating oxidation represent the matrix of amorphous nickel polyphosphates and polyphosphoric acids where fine Ni-P particles are distributed. Such composite structure is a well light absorbing medium. Formation of hypophosphite protective layer on the Ni–P coating obtained from saccharin free electrolyte reduces the thickness of light absorbing layer and changes its composition. Thus light absorbance ability of the coatings can be caused by both distribution of fine nickel-phosphorus particles in dielectric matrix and specific microstructure of their surfaces.

Hertzian Indentation Behavior of Electroless Ni-P-Ti Composite Coatings

Ni-P-Ti composite coatings have been prepared by co-depositing Ni-P and nano-Ti particles which were then annealed. Tensile tests were conducted on standalone coatings to acquire the mechanical properties of the coatings without the effect of the steel substrate. The Hertzian indentation tests were performed on coating-steel substrate bilayer systems to investigate the indentation behavior of the coatings. After annealing, Ni3Ti and superelastic NiTi phases are identified in composite coatings by XRD and EDS. Compared to the as-deposited Ni-P coatings, the toughness of the annealed composite coatings improved significantly. The superelastic effect of NiTi particles was observed in the Hertzian indentation behavior of the annealed composite coatings. The strengthening mechanisms as well as toughening mechanisms such as crack bridging, crack deflection, crack arresting, and transformation toughening were discussed. Recovery ratio (η) values as well as Hertzian indentation stress distribution were computed to analyze and explain the indentation behavior of the as-deposited and annealed coatings.

Design and controllable synthesis of core-shell nanostructured Ni-P particles with an ionothermal strategy

Designed core-shell nanostructured of Ni-P alloy particles are fabricated by a controllable ionothermal strategy. Based on advanced first-principles calculations, the Ni3P composite exhibit a decreased vacancy formation energy (6.130 eV) and diffusion activation energy (−0.347 eV) compared with those of Ni4.5P. Notably, the size and composition of the as-prepared Ni-P alloy nanoparticles can be effectively controlled by using different nickel (NiSO4·6H2O, NiCl2·6H2O, and Ni(NO3)2·6H2O) and pyrophosphate sources (NaH2PO2·H2O and NH4H2PO2). The structural information of the as-prepared particles is characteristic of an amorphous Ni-P solid solution which homogeneously covered by a self-generated crystalline nickel pyrophosphate shell. The thickness of the crystalline shell surrounding the amorphous core is dependent on the molar ratio of Ni2+/H2PO2− in the reaction solution. Furthermore, as negative electrode materials for lithium ion batteries, the Li storage behaviours of the as prepared Ni-P alloy nanoparticles are investigated by both electrochemical tests and first-principles calculations. Of the prepared nano particles, those samples with high P contents and small particle sizes exhibit improved capabilities and cycling performances.

Preparation and characterization of bimetallic Pt^Ni-P/CNT catalysts via galvanic displacement reaction on electrolessly-plated Ni-P/CNT

Platinum-based bimetallic catalysts have broad applications in polymer electrolyte membrane fuel cells and water splitting. In this work, galvanic displacement reaction was employed to prepare Pt^Ni-P/CNT catalysts using electrolessly-plated Ni-P/CNT. These catalysts were extensively characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Catalytic activities towards methanol oxidation and hydrogen evolution reactions were evaluated and benchmarked with a commercial Pt/C catalyst. Uniform dispersion of Pt on Ni-P particles led to high Pt utilization, and the electrochemical surface area of Pt^Ni-P/CNT with 12.1% Pt loading was found to be 126 m2 g−1, higher than that of a commercial Pt/C (77.9 m2 g−1). The Tafel slopes for the Pt^Ni-P/CNT catalysts were also found to be smaller than that of Pt/C indicating faster kinetics for hydrogen evolution reaction.

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

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

Microstructure and Mechanical Property of Hot-Pressed Al2O3-Ni-P Composites Using Ni-P-Coated Al2O3Powders

Al2O3-Ni-P composite powders with Ni-P contents of 10.9, 14.4, and 20.4 wt.% were synthesized via the Ni-P electroless deposition process. The as-received Al2O3-Ni-P composite powders were composed of Ni-P particles and Ni-P coating layer. Some Ni-P particles randomly adhered to the Al2O3powders, and their particle diameter ranged from 5 nm to 20 nm. The thin Ni-P layer had about 5 nm thick amorphous structure and directly bonded with Al2O3powders. Using the Ni-P-coated Al2O3powders, a dense Al2O3-Ni-P composite can be successfully obtained using the hot press process at 1,350°C for 1 hour in an Ar atmosphere under an applied pressure of 30 MPa. The hot-pressed Al2O3-15 wt.% Ni-P composite showed excellent material properties. Its relative density, Vickers hardness, and fracture toughness were comparatively high: about 99.1%, 2,360 Hv, and 6 MPa·m1/2, respectively. The fracture surface of the hot-pressed Al2O3-Ni-P composite showed a semiductile mode due to the mixed intergranular and transgranular fracture mode. In particular, the fracture toughness of the hot-pressed Al2O3-15 wt.% Ni-P composite was strongly enhanced by the combined action of the crack branching and the crack deflection.

Glass–NiP–CoFeP Triplex-Shell Particles with Hollow Cores and Tunable Magnetic Properties

Low density (0.55-0.92g/mL, depending on the shell thickness and composition) glass-metal-metal triplex-shell hollow particles (TSHP) were prepared by a three-step route. First, micrometer-sized silicate glass particles with hollow cores, uniform shells, and high sphericity were prepared through spray drying and subsequent melting. NiP shell was uniformly assembled to the previously obtained glass hollow particles by silver seed induced chemical reduction of Ni(2+) by sodium hypophosphite, and glass-NiP double-shell hollow particles (DSHP) with compact and uniform shells were formed. The as-formed NiP particles further acted as the seeds for the directed formation and assembly of the CoFeP shell on the NiP shell to form the final glass-NiP-CoFeP triplex-shell hollow particles (TSHP). The influences of the component of the reaction system on the composition, structure, and magnetic properties of the hollow particles were studied. The multishell hollow particles thus obtained may have some promising applications in the fields of low-density magnetic materials, conduction, microwave absorbers, catalysis, etc. This work provides an additional strategy to fabricate multishell structured hollow particles with tailored shell composition and magnetic properties, which can be extended to the controlled preparation of multishell composite particles with the shells consisting of metal, oxides, or other compounds.

Resonance Scattering Detection of Trace Hg2+ Using Aptamer‐modified AuPd Nanoalloy Probe as Catalyst

AbstractThe 5 nm AuPd nanoalloy in mole ratio of Au:Pd=32:1 was prepared, using sodium citrate as the stabilizing agent and NaBH4 as the reductant. The AuPd nanoalloy was modified by the aptamer to prepare an aptamer‐ AuPd (AptAuPd) probe for resonance scattering (RS) detection of 5.0–1250 nmol/L Hg2+. The AptAuPd‐Hg2+ aptamer reaction solution was filtrated by membrane, and the AptAuPd in the filtrate exhibited strong catalytic effect on the slow NiP particle reaction between NiCl2 and NaH2PO2, and the NiP particles showed a RS peak at 508 nm. The RS intensity decreased when Hg2+ concentration increased. The decreased RS intensity was linear to Hg2+ concentration in the range of 0.5–1250 nmol/L. The RS assays were used to determine Hg2+ in real samples, with good results.

Study on the Effect of Ultrasonic Waves on the Low Temperature Electroless Ni-P Plating on Copper Substrate

In this paper，electroless Ni-P plating on copper substrate at 50 °C in ultrasonic field was carried out. The frequency of ultrasonic waves was 40 kHz. The effect of ultrasonic on the composition, plating rate and morphology of Ni-P deposite was investigated at the ultrasonic power of 40, 70 and 100 W. The experimental results showed Ni-P deposit could not be obtained without ultrasonic field at 50 °C. The content of nickel and the thickness of Ni-P deposit increased with the ultrasonic waves power increase. Ultrasonic irradiation power remarkably refines the nodule size of Ni-P particles. The collapse of cavities in solution seems to suppress the Z-direction growth of the nodule.

An investigation of porous structure in molecularly imprinted polymer for sensor development: Non-linear fluorescence quenching of 17β-estradiol bound inside MIP submicron particles by sodium nitrite and methacrylamide

17β-Estradiol (E2) molecularly imprinted and non-imprinted poly(methacrylic acid-co-ethylene glycol dimethacrylate) submicron particles (MIP and NIP) have been synthesized in the presence and absence of template E2 molecules. The sizes of MIP and NIP particles were determined via a nanoDLS particle size analyzer to be 477 ± 11 and 373 ± 21 nm. After these naturally non-fluorescent MIP and NIP particles bound with E2 molecules as a fluorophore, strong fluorescence at λ em = 310 ± 1 nm was detectable when excited by light of λ ex = 280 ± 1 nm. Sodium nitrite and methacrylamide were selected as two fluorescence quenchers with different ionic/molecular sizes. They both exhibited non-linear quenching behavior in the Stern–Volmer plots. The smaller quencher (sodium nitrite) ionized in water to produce nitrite anions that easily penetrated into the porous MIP particles and quenched the fluorescence emission from the E2 molecules bound inside. It produced a dynamic quenching constant ( K sv) of 23.0 ± 1.3 M −1 when the concentration of E2–MIP particles was 2.5 mg/mL in water. The larger quencher (methacrylamide) was sterically hindered in penetrating the pores of MIP particles. Its dynamic quenching constant ( K sv) hence became small, to be less than 1.0 ± 0.5 M −1. This approach enabled an investigation of the porous structure in MIP particles for development of a novel E2 sensing scheme.

Characterization of molecularly imprinted and nonimprinted polymer submicron particles specifically tailored for removal of trace 17β‐estradiol in water treatment

AbstractThis study investigated the potential use of molecularly imprinted polymer (MIP) submicron particles for the selective removal of trace 17β‐estradiol (E2) in water treatment. Methacrylate‐based MIP submicron particles were synthesized, in a one‐step suspension polymerization procedure, using ethylene glycol dimethacrylate (EGDMA) as the cross‐linker. After template removal, the particles could be used as a smart material for specific binding of E2. The submicron size of MIP particles facilitated uniform dispersion in water for up to 17 days. These particles were meritorious in mass transfer behavior, allowing phase partitioning of E2 molecules in water during a short treatment time. After 1‐mL water samples of different E2 concentrations were treated with 20 mg of MIP particles for 2 min, recovery percentages as high as 97% ± 3% were achieved. The specific binding capacity of these MIP particles was determined to be 15 mg E2/g. Nonimprinted polymer nanoparticles were also evaluated for nonspecific binding of E2, using 0.5 mg in 1 mL of water, to attain 64% ± 3% efficiency in 3 min towards general water treatment. A simple capillary electrophoresis method was successfully developed for the characterization of MIP and NIP particles. Apparently the less negative the electrophoretic mobility, the higher binding efficiency and faster binding kinetics the particles would exhibit with E2 due to less hindered Brownian diffusion. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Molecular imprinted particles for lysozyme purification

Molecular recognition-based separation techniques have received much attention in chemistry and biology because of their high selectivity for target molecules. The aim of this study is to prepare lysozyme-imprinted polymers which can be used for the purification of lysozyme from aqueous solutions and egg white. N-methacryloyl-( l)-histidinemethylester (MAH) was chosen as the metal-complexing monomer. In the first step, Cu 2+ was complexed with MAH and the lysozyme-imprinted poly(HEMA–MAH) [Lys-MIP] particles were synthesized by UV-initiated bulk polymerization. After that, the template (i.e., lysozyme) were removed using 0.1 M NaCl solution. The specific surface area of the Lys-MIP particles was found to be 22.9 m 2/g with a size range of 20–63 μm in diameter and the swelling ratio was 57%. According to the elemental analysis results, the particles contained 421 μmol MAH/g polymer. The maximum lysozyme adsorption capacity was 12.1 mg/g polymer. The relative selectivity coefficients of imprinted particles for lysozyme/human serum albumin and lysozyme/cytochrome c were 3.6 and 4.1 times greater than NIP particles, respectively. Purification of lysozyme from egg-white was also monitored by determining the lysozyme activity using Micrococcus lysodeikticus as substrate. The purity of the desorbed lysozyme was about 89% with recovery about 84%. The Lys-MIP particles could be used many times without decreasing their adsorption capacities significantly.

Influence of Temperature and Pressure on the Possibility of Obtaining Al<sub>2</sub>O<sub>3</sub>/Ni-P Nanocomposite through Hot Pressing Process

The influence of sintering temperature and high pressure on Ni-P nanoparticles in Al2O3/Ni-P nanocomposites was investigated in this paper. The fine-grained alumina powder was covered with Ni-P nanoparticles of 20 – 50 nm size by electroless nickel plating. The material was sintered in temperatures from 900 to 1400oC using pressures above 5 GPa. It was found that sintering in such conditions give a possibility to maintain nanometrical size of Ni-P particles. In the case of 1400oC the metallic phase melts and non-uniform grain growth of ceramic was observed. Hot pressing at 900oC allowed for the metal to remain in solid state and ensured uniform microstructures of the nanocomposites, with uniform distribution of nanometrical Ni-P grains in the ceramic matrix. In this temperature the grain growth of the ceramic was not observed. The results are discussed in terms of technology for production of ceramic-metal composites for various applications.

Direct Plating of Electroless Ni-P Layers on Sputter-Deposited Al-Ni Alloy Films

Direct plating of electroless Ni-P layers on Al-Ni alloy films formed on glass substrates was performed using magnetron-sputtered deposition and ion beam-assisted deposition methods. Dissolution of Al from the alloy films occurred in the initial stage of the plating process and resulted in enrichment of Ni on the surface. Since Ni acts as a catalyst for the Ni-P deposition reaction, Ni-P deposition occurs on the alloy surface without zincate pretreatment. In the case of an Al-10Ni alloy film, however, Ni clusters dropped from the Al-Ni alloy surface, and Ni-P particles grew in the plating bath, causing dissipation of chemicals in the bath. Such particles also readhered to the surface, resulting in a nonuniform plating layer. A lower concentration of Ni in an alloy such as an Al-3Ni or Al-1Ni alloy resulted in a rather smooth plating surface. In the case of a neutral plating bath containing a low concentration of P, cone structures were formed in the plating layer. Such structures seem to form at the nucleation sites of Ni deposition in the initial stage of the plating process. © 2003 The Electrochemical Society. All rights reserved.