Watts Nickel Research Articles

On the synthesis of oil-containing microcapsules and their electrolytic codeposition

Composite coatings consisting of a metal matrix in which ceramic particles are embedded have recently been developed and used in industry as wear-resistant coatings. The present paper deals with the development of oil-containing self-lubricating metallic coatings. These have been produced by electrolytic codeposition of oil-containing microcapsules from Watts nickel plating baths. For this purpose, oil-containing polyterephthalamide microcapsules were synthesized based on the interfacial polymerization of an oil-soluble monomer (terephthaloyl dichloride) and a mixture of two water-soluble monomers (diethylenetriamine and 1,6-hexamethylenediamine). The influence of several synthesis parameters (e.g. type of encapsulated organic phase, monomer concentration(s) and concentration ratio of the two amine monomers) on the size distribution and morphology of the oil-containing polyamide microcapsules as well as on their electrolytic codeposition behaviour is discussed. As revealed by scanning electron microscopy analysis, the morphological characteristics of the microcapsules were affected to a great extent by the functionality of the water-soluble amine monomer. Furthermore, the composition of the core material of the microcapsules showed a marked influence on their stability upon aging in the Watts nickel plating bath. Finally, codeposition experiments using a laboratory rotating electrode showed that the level of codeposition was influenced by the presence of additives in the nickel electrolyte and was strongly dependent on the polymerization conditions employed in the microcapsule synthesis.

Codeposition of SiC powders with nickel in a Watts bath

The effect of the silica layer of SiC powder on ionic adsorption was studied in a Watts nickel plating bath. PZC (point of zero charge) measurement suggested that SiC powder has a tendency to release H+ at pH > PZC (∼ 2.2), and the amount of Ni2+ adsorbed on the surface of the SiC increased with increased pH of the Watts bath. Experimental results showed that SiC powders not only catalyzed the adsorption of hydrogen atoms but also had a significant effect on hydrogen evolution during electrodeposition if the solution pH was less than or equal to 2.0 (∼PZC. Furthermore, SiC powders have a shielding effect which prevents OH− from being released into the solution under an applied potential, which results in more Ni(OH)2 in the deposited layer. SiC powders also promote further adsorption of intermediates of nickel on the electrode surface, as shown by impedance studies.

Metal Distribution in Jet Plating

Jet plating is a high‐speed electroplating technique. Due to its special flow characteristics it can be used to localize the electrodeposition reaction on an unmasked cathode. In this process, a jet of plating solution is directed to a cathode surface, and electroplating is done by applying an electric field between the cathode and an anode located in the jet nozzle. The electric current travels along the jet stream to the cathode, and electrodeposition reaction takes places locally only on the area where the jet impinges on the cathode surface. The objective of this study is to find the metal thickness distribution on the cathode surface as a function of current density, electrolyte composition, electrolyte velocity, and nozzle height. Copper plating from an acidic copper sulfate bath and nickel plating from a Watts nickel bath and a nickel sulfamate bath were studied.

Electrochemical characterization of electrodeposited chromium and nickel-chromium layers on a steel substrate

Chromium was deposited on steel specimens and on electroplated steel specimens covered with a Watts nickel layer. The influence of the substrate and of the crack pattern of the electrodeposited chromium layer on the passivation and the reactivation behaviour has been studied by means of potentiodynamic polarization curve measurements and cyclic voltammetry. In the results of the above mentioned electrochemical measurements a strong influence of the substrate was found for a cracked chromium layer deposited on the steel specimen and for a cracked chromium layer deposited on a 30 μm Watts nickel layer. No influence of the substrate was found in the case of a crack-free chromium layer deposited on the steel substrate or on a Watts nickel layer. It is thus possible to determine whether the chromium layer is cracked or crack free by recording a polarization curve or a cyclic voltammogram for a chromium-plated system. A mechanism is proposed for the passivation and repassivation of cracked chromium layers electrodeposited on a steel substrate or on a Watts nickel layer.

Ｎｉ‐ＳｉＣ分散めっきの粒子‐マトリックス接着と引張特性

A trial has been conducted to bond 1μm α-silicon carbide particles firmly with the Watts nickel matrix of the coating, by annealing the coating at temperatures as low as possible and at a reasonable rate. Formation of a strong bonding was found on annealing the coating at 600°C. The bonding reaction, as detected and characterized by tensile testing, X-ray diffraction, scanning and transmission electron microscopy, was found to have an incubation period of two minutes and then proceeded to form a bonding layer, which was a composite; SiC/Ni5Si2/Ni3Si/graphite/Ni. On further annealing at 600°C, the dispersed particles transformed into Ni3Si particles coated with graphite film. The bonding erased the easy crack at the particle/matrix interface, generated a ductility of the coatings, and doubled the tensile strength of a coating at 400°C. The strengthening was described in terms of the Orowan mechanism, wherein a reaction-induced particle growth was considered. Some properties of the coatings were described on the basis of the dense random packing of the dispersed particles. A reaction was found at the SiC/Ni interface even on 500°C annealing, but with the incubation period of about five hours.

キレート試薬によるニッケルめっき液中の微量銅イオンの選択除去

The selective removal of trace copper (II) ion in Watts nickel bath was studied by using chelating reagents, 2-quinolinecarboxylic acid (QA), N-nitroso-N-phenylazanol ammonium salt (CP), 2-mercapto-benzothiazole (MBT), and (2-hydroxylphenylmethylene) azanole (SA). These chelating reagents formed insoluble complexes with copper (II) ion in the bath. Residual copper (II) ion lower than 0.1mg/l was attaind by the addition of MBT or SA, whereas the residual ion was below 5mg/l for QA or CP. Since the chelating reagents have harmful effects on the appearance of nickel deposits, the bath had to be treated with activated carbon prior to use. Amounts of activated carbon, required for reducing the concentration of chelating reagents from 100mg/l to harmless value, 10mg/l, were 0.7, 1.4, 3.0 and 4.0g/l for MBT, SA, QA and CP respectively. Activated carbon modified with the chelating reagent was also useful for the selective removal of copper (II) ion. Additional activated carbon treatment was not necessary, because the desorption of SA from the modified activated carbon into Watts bath was too little to be harmful.

Ｎｉ‐Ａｌ?S２?TＯ?S３?T及びＮｉ‐ＺｒＯ?S２?T分散めっきの生成条件

Electrodeposition of Ni-Al2O3 and Ni-ZrO2 from a Watts nickel bath has been studied to determine the factors affecting the codeposition of the oxide particles into nickel matrix. The amount of the oxide particles codeposited into the nickel deposits was found to increase linearly with decreasing pH of the plating bath under the constant current density. Higher content of the oxide particles in the deposits was observed at lower current densities. The surface appearance and hardness of the composite coatings as well as the contents of the oxide particles were affected by the organic cations such as fluorescent dye or crystal violet. It was confirmed that nickel ions, protons, and/or organic cations are adsorbed on the oxide particles bringing about the positive surface charge, and thus they promote the entrapment of the oxide particles into the nickel deposits. Codeposition of the oxide particles into nickel matrix can be explained by the hydrodynamic transport of the particles and the field-assisted electrosorption of the oxide particles to the cathode, and finally by the electrochemical entrapment of the particles into the growing crystal.

A Statistical Approach to Barrel Plating

SummaryThe effects of variations in type of load, percentage volume barrel loading and effective current density on cathode current efficiency, barrel efficiency and distribution of metal on components in the load have been studied. A small horizontal barrel was employed, the plating solution being of the Watts nickel type. The main information revealed by multiple regression analysis, making use of computer techniques, was as follows, (i) Cathode current efficiency had a relationship with only one independent variable (percentage volume loading) and even then only in the case of one type of load (discs), (ii) Barrel efficiency increased as percentage volume loading was increased but was not affected significantly by variation in current density, (iii) Standard deviation of coating weights decreased as the percentage volume loading was increased but it increased as the current density was increased.

The Effects of Annealing on the Mechanical Properties of Electrodeposited Nickel

SummaryAttempts have been made to clarify the existing experimental evidence of the embrittlement of Watts nickel after heat treatment at temperatures in excess of 600°C. Electrodeposits have been prepared from a ‘purified’ solution maintained at pH 4 at current densities of 21·5, 270 and 540 A/m2. It was found with 21·5 A/m2 nickel that the ductility (measured at 20°C) was drastically reduced as the annealing temperature (1 h treatment) increased from 600° to 1000°C, whilst the higher current density materials only registered a small reduction in this property after treatment close to 1000°C. The UTS decreased with increasing annealing temperature in all cases. Metallographic observations revealed that the intergranular embrittlement observed in the low current density nickel was due to the presence of grain boundary discontinuities. These were identified as voids by scanning electron microscopy, and confirmed by specific gravity measurements. Grain boundary voids were also observed in the annealed high ...

Preparation of Coumarin Derivatives and their Evaluation as Additives for Nickel Plating Solutions

SummaryAnalysis of the behaviour of coumarin and its breakdown products suggested that coumarino-7, 8-α-pyrone might be a levelling agent with less deleterious effects on the deposit. The compound was made, and shown to be sparingly soluble in Watts nickel plating solution and to exhibit moderate levelling power. It slightly reduced internal stress while the plate remained ductile and semi-bright. These properties were maintained over a longer period of use than was possible with a coumarin bath but the levelling power of the pyrone fell, with time, to a negligible value. It is concluded that unfavourable adsorption of the cathodic reduction product probably persists with this derivative of coumarin.

The Effect of Metallic Contamination on the Structure and Ductility of Electrodeposited Nickel

SummaryTransmission electron microscopy has been used to investigate the structure of nickel electrodeposits plated from solutions containing copper and zinc as contaminants. Ductility of deposits was determined and subsequently deformed deposits were examined by transmission electron microscopy. An addition of copper or zinc (within concentration range 0–0.134 g/1 metal ion) to the dull Watts nickel solution did not result in significant changes in microstructure or ductility at 40 A/ft2, 135°F and pH 4. Additions of copper or zinc to a semi-bright nickel solution (Watts +0·1 g/1 coumarin) resulted in a small grain size and a moderate reduction in ductility. The dislocation density in deformed deposits was increased and strain fields formed at twin boundaries.

Note on the structure of nickel deposited from sulphamate solutions

Earlier work on the structure of deposits from the Watts nickel solution has been extended to an examination of the structure of deposits from the nickel sulphamate bath, which can be operated at very high cathode current density and overpotential. Even at overpotentials > 1 V, very short deposition times produced structures very similar to those found in Watts nickel deposits formed at much lower overpotentials.

Electron-microscope studies of the structure of nickel deposited in the presence of addition agents

The effects of a series of organic additions and of two inorganic additions on the structure of Watts nickel as revealed by electron microscopy are discussed in terms of their previously reported influence on surface reflectivity. A comparison with bright nickel—cobalt deposits has been made.The morphology of growth is discussed and tentative suggestions advanced in an attempt to explain and account for the different structures that have been observed. It is concluded that the most effective brighteners are those which not only bring about considerable reduction in grain size but in addition, and possibly even more important, can exercise a smoothing influence by favouring the development of a uniform polycrystalline surface as distinct from one showing pyramidal, truncated pyramidal, or block types of growth.

The effects of coumarin on the electrodeposition of nickel

Systematic variations in the thickness of the diffusion boundary layer over a rough surface are an essential factor in producing the levelling action of metals electrodeposited in the presence of levelling additives. Information on the behaviour of these additives at an electrode at which metal is being deposited and their effects on metal deposition under conditions of known diffusion-layer thickness is therefore valuable for understanding the mechanism of levelling. Experiments are described which show that the behaviour of additives in the electrodeposition of metals can be studied under conditions of known rates of transport of additive to the electrode using a rotating disk electrode.In the deposition of nickel from a Watts-type solution, coumarin reduces the current efficiency for nickel deposition. The current efficiency for hydrogen evolution is increased, the coumarin encouraging evolution from a few points on the electrode.The analysis of products has confirmed that reduction to melilotic acid is the principal cathodic reaction of coumarin but there is a small amount of a second product. Coulomb balances show that this is a product involving the addition of many more than two electrons to each coumarin molecule.The diffusion coefficient for coumarin in the Watts nickel solution has been measured and used to calculate rates of transport of coumarin to the cathode under various conditions. These have been compared with measured rates of coumarin consumption. The comparison has shown conditions where the rate of consumption is transport controlled and where it is electrochemically controlled.The levelling power of coumarin on a rough surface has been derived from the results. This shows maxima in levelling power as a function of coumarin concentration resulting from the change over from transport to electrochemical control of the rate of coumarin consumption.

The Effects of Some Aromatic Sulphonic Acids on the Stress, Structure, and Composition of Electrodeposited Nickel

SummaryA systematic study has been made of the efiects of certain aromatic sulphonic acids added to a Watts nickel bath. Benzene derivatives contribute sulphur but no carbon to the deposits which are characterized by (100) orientations. Deposits obtained from baths containing naphthalene derivatives are usually characterized by a random structure or a (110) orientation and contain sulphur but no carbon unless nitrogen is present in the addition agent molecule when all three elements are present in the deposits. Solutions containing naphthylamine mono-sulphonic acids transfer the entire brightener molecule to the deposit. Benzene derivatives and naphthalene sulphonic acids reduced the stress normally present in Watts nickel. Naphthol sulphonic acids and naphthyl- amine sulphonic acids lead to an inverse form of the usual stress/thickness relationship. The greater the separation of substituent groups in the latter compounds, the more pronounced is the initial rise in stress and the higher the final stress l...