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This paper aims to report a study of the influence of tungsten carbide (WC) nanoparticles on corrosion resistance properties of electroless nickel–phosphorus (Ni–P) coatings in NaCl solution.

The morphology of Ni–P–WC nanocomposite coatings was observed by scanning electron microscopy (SEM). The anodic polarization curves, electrochemical impedance spectra (EIS) and weight loss measurements were used to study the corrosion resistance properties of Ni–P–WC nanocomposite coatings in NaCl solution.

The WC nanoparticles content in the coatings increased with the increase of its concentration in the bath, and the WC nanoparticles are uniformly distributed in Ni–P alloy matrix. The results showed that the incorporation of WC nanoparticles elevated the corrosion resistance properties of Ni–P alloy matrix.

This study shows that the corrosion resistance was improved by the addition of WC nanoparticles to the Ni–P alloy matrix.

This paper aims to select parameters such as temperature thermal stability and temperature coefficient of resistance (TCR) for Ni–P resistive alloys obtained by electroless metallization. Ni–P alloys are used in the manufacture of precision resistors characterized by TCR in the range of ± 10 ppm/K. The correlation of the technological parameters with the electrical properties of resistors enables the accurate prediction of the TCR resistors.

The Ni–P layers were obtained by a continuous process at about 373 K in a solution with the acidity of pH = 2 and then dried for two hours at 393 K. Subsequently, the Ni–P layer was stabilized for two hours in the temperature range of 453-533 K. Resistance was measured with an accuracy of 1 mΩ. TCR was determined with an accuracy of 1 ppm/K in the temperature range 298-398 K. In the next stage of the investigation, the increase in TCR of the Ni–P alloy was correlated with the increase in stabilization temperature. Scanning electron microscope images of the alloy surface were studied to assess grain sizes and to relate the average grain size with TCR values of resistive alloys. The X-ray diffraction analysis was performed to determine the crystallization temperature of Ni–P alloy.

The conducted investigation showed that the TCR increase in alloy is a linear function of stabilization temperature in the temperature range in which transition from amorphous phase to crystalline phases did not occur. TCR increase in Ni–P alloy arises from the increase of average size of grains resulting in decrease of scattering of electrons on grain boundaries. The analysis of alloy composition in chosen fragments of surface shows inhomogeneity growing with decreasing analyzed surface dimensions which proves that, before the stabilization, the structural arrangement of alloy is inconsiderable.

The obtained results are the first attempt to relate the morphology of surface with TCR of alloy and demonstration of linear dependence between an increase in TCR of amorphic Ni–P alloy and stabilization temperature of resistive layer. Such correlations are not described in available literature.

The purpose of this paper is to characterize electrical parameters of amorphous Ni‐P resistive layers used for fabrication of precise resistors.

Ni‐P resistive layers were produced by the chemical process in water solution using Ni^2 + and H₂PO₂⁻ ions. The paper presents the results of the studies concerning the influence of bath acidity and conditions of thermal stabilization on the structure and temperature coefficient of resistance of Ni‐P alloy.

The temperature coefficient of resistance of amorphous Ni‐P layers was found to depend significantly on the parameters of chemical metallisation process. It was stated that the changes of through‐casing resistivity versus the acidity of technological solution have roughly parabolic characteristics.

In this paper, it was at first explained how the changes of the structure of Ni‐P resistive layers depend on their temperature coefficient of capacitance.

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.

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.

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.

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.

The paper aims to present a research on the impact of the stabilization process of a thin metallic layer (Ni-P) produced on a ceramic surface (Al₂O₃) by means of electroless metallization on its electric parameters and structure. On the basis of the research conducted, the existence of a relationship between resistance (R) and the temperature coefficient of resistance (TCR) of the test structure with a Ni-P alloy-based layer and the temperature of stabilization was proposed.

Metallic Ni-P layers were deposited on sensitized and activated substrates. Metallization was conducted in an aqueous solution containing two primary ingredients: sodium hypophosphite and nickel chloride. The concentration of both ingredients was (50-70) g/dm³. The process lasted 60 min, and the metallization bath pH was kept at 2.1-2.2, whereas the temperature was maintained at 363 K. The thermal stabilization process was conducted in different temperatures between 453 and 623 K. After the technological processes, the resistance and TCR of the test structures were measured with a micro ohmmeter. The composition and the morphology of the resistive layer of the structures examined was also determined.

The dependence of the resistance on the temperature of the stabilization process for the temperature range 553 to 623 K was described using mathematical relationships. The TCR of test resistors at the same thermal stabilization temperature range was also described using a mathematical equation. The measurements show that the resistive layer contains 82.01 at.% of nickel (Ni) and 17.99 at.% of phosphorus (P).

The results associate a surface morphology Ni-P alloy with the resistance and TCR according to temperature stabilization. The paper presents mathematical relationships that have not been described in the literature available.

The purpose of this paper is to present the possibility of technology of chemical metallization for the production of electrodes and resistors based on Ni–P alloy on silicon (Si), alundum (Al₂O₃) and low temperature cofired ceramic (LTCC) substrates. The developed technology provides low cost in any form.

During the study monocrystalline Si plates and Al₂O₃ and LTCC substrates were used. On the surface of the substrates, the electrodes (resistors) by the electroless metallization were made. Subsequently, the electrical parameters of obtained structures were measured. Afterwards, trial soldering was made to demonstrate that the layer is fully soldered.

Optimal parameters of the metallization bath were specified. As a result of the research conducted, it has been stated that the most appropriate way leading to the production of soldered metal layers with good adhesion to the portion of selectively activated Si plate and Al₂O₃ and LTCC substrates comprises the following technology: masking, selective activation, nickel-plating of activated plate. Such obtained metal layers have a great variety of application; in particular they can be used for the preparation of electric contacts in Si solar cells, production of electrodes and resistors and production of electrodes in thermoelectric structures.

The paper presents a new, unpublished method of manufacturing electrodes (resistors) on Si plate and Al₂O₃ and LTCC substrates.

The purpose of this paper is to elucidate the tribology behavior of polytetrafluoroethylene (PTFE) incorporated with three types of nickel–phosphorus (Ni-P) particles (i.e. low phosphorus [LP], medium phosphorus [MP] and high phosphorus [HP]) under dry sliding condition.

Ni-HP, Ni-MP and Ni-LP particles fabricated via an electroless plating process were incorporated into PTFE matrix with different additions to prepare Ni-P/PTFE composites (Ni-LP/PTFE, Ni-MP/PTFE and Ni-HP/PTFE). The tribology tests for these samples were carried out on a reciprocating ball-on-disc tribometer. The thermal stabilities, mechanical and tribological properties, morphologies and components of aforesaid Ni-P/PTFE composites were analyzed.

The marvelous effect of Ni-P incorporation on the simultaneous reduction in friction and wear of PTFE was corroborated.

Compared with that of pristine PTFE sample, the reduction on friction with a value of 27% and the reduction in wear about 94% for Ni-HP/PTFE composite is validated, which is probably related to the increased crystallinity and hardness due to the presence of Ni-P particles.

The purpose of this paper is to determine the appropriate conditions for the chemical deposition of Ni‐P‐Al₂O₃ composite coatings, deposited on metalic matrix.

Auto catalytic reduction of Ni in nickel sulfate and sodium hypophosphate bath, including 10 percent volume fractions of nanodispersive Al₂O₃ particles is treated in the alloy steel 100Cr6. The wear resistance and friction coefficient of the coatings are determined using tester T‐01M, a ball‐disc tester for mitigated solid friction conditions, in model lubricants: oil bases, oil bases with antiwear additives AW.

The analysis of the properties of the Ni‐P‐Al₂O₃ deposits confirms that the presence of the dispersion phase of aluminium oxide determines the coating wearability.

The paper presents some indications of proper selection of antiwear coating generation methods (their parameters and conditions).

Investigations show that tribocatalytic effect of nickel coatings influence the intensity of antiwear layers generation in zinc dialkyldithiophosphates (ZDDP) tribochemical interaction in model lubricants and that tribochemical, adsorption, and reaction‐diffusion effect of ZDDP, decided on great effectiveness of generated antiwear surface layers, which was confirmed by the results of tribological investigation.

The purpose of this paper is to evaluate the corrosion resistance of the electroless Ni‐P coatings in two aggressive media 3.5 wt.% NaCl and Synthetic industrial waste water. Also to study the effect of Phosphorous content in the electroless Ni‐P deposits on its surface nature, morphology and corrosion resistance.

The corrosion behavior of electroless Ni‐P coatings generated on mild steel coupons from an acidic and an alkaline baths and their anti‐corrosion performance of was compared systematically in 3.5 wt.% of NaCl solution and also in synthetic industrial waste water. Microstructure and surface composition of coatings were analyzed using X‐ray diffraction, scanning electron microscopy and energy dispersive spectroscopy techniques, respectively. The Ni‐P coated mild steel specimens were subjected to corrosion and the rate of corrosion was studied by chemical and electrochemical methods. The linear sweep voltammetry, Tafel and electrochemical impedance spectroscopy were employed to obtain corrosion data.

The electroless Ni‐P coatings with higher P content possess homogeneous, uniform and amorphous surface nature and exhibited higher corrosion resistance in the aggressive corrosive media chosen.

This paper provides corrosion behavior of electroless Ni‐P coatings in 3.5 wt.% NaCl and synthetic industrial waste water, and establishes the importance of phosphorous content on nature and properties of the coatings.

This paper discusses the lower concentration reinforcement of cathodic ultrafine ceramic particulates, on metal matrices like Zn, Al and alloy‐matrices like Cu Zn, Cu Mn, Al Zn and Ni‐P‐B alloy‐electrodeposits, etc. It is assumed that these ultrafine ceramic particulates in lower concentration‐range are effective in covering the anodic grain‐boundary networks and other anodic‐defect sites, such that there is an effective reduction of surface anodic‐current. It is shown that at a critical threshold particulate concentration, the surface dissolution is minimum, followed by a drastic increase above that concentration. Such increase in dissolution is attributed to the random dispersion of the particulates on the grain‐proper, as these cannot be accommodated within the anodic grain‐boundary channels, micro‐voids and other defect sites. As such they form stress‐raiser points and enhance surface dissolution. This paper also discusses the correlation of the grain boundary structures, particulate trapping capacity of the matrix and the galvanic stress factors due to random distribution of particulates.