Codeposition Of Particles Research Articles

Effect of specimen orientation and heat treatment on electroless Ni-PTFE-MoS2 composite coatings

In this study, the effects of simultaneous co-deposition of polytetrafluoroethylene (PTFE) and MoS2 particles on tribological properties of electroless nickel (EN) coating were studied. The influences of specimen orientation and heat treatment on EN-PTFE-MoS2 composite coatings were also investigated. Scanning electron microscopy was used to study the morphology of coatings and the distributions of the lubricant particles in the deposits. Chemical analyses of coatings were done by electron dispersive spectrometry. The phases of the coatings were identified by X-ray diffraction utilizing CuKα radiation. Wear and friction properties of the coatings were also determined by pin-on-disk wear tester. The wear investigations showed that the EN-PTFE-MoS2 composite coating performs better than EN-PTFE and EN-MoS2 coatings in terms of friction coefficient and wear resistance. PTFE and MoS2 contents of the EN-PTFE-MoS2 coating were increased by changing the specimen orientation from vertical to horizontal configuration, which leads to enhancement in tribological properties of the coating. After heat treatment, the wear rate of EN matrix composite coating decreased with corresponding change in phase structure.

Electrodeposition of Cu + PdO and ( Cu – Pd ) + PdO Composites

The codeposition of PdO particles with a Cu matrix has been investigated with the aim of extending the composite deposition procedure to the preparation of materials potentially capable of catalyzing the low temperature combustion of methane. composites with a low dispersed phase content were obtained from either basic pyrophosphate or acid sulfate baths. Codeposition of PdO particles with a Cu–Pd alloy matrix was effectively achieved by electrolyzing suspensions of PdO in solutions containing both and ions, with large ratios. deposits with 20–25 Pd atom % were obtained in which only 1–2 atom % of Pd were alloyed in the matrix. These composites were mechanically stable and highly porous throughout their thickness (their pore volume being ca. 60% of the total volume). Their true surface area was some thousands of times higher than their geometric area.

Electrodeposition of Cu+PdO and (Cu-Pd)+PdO Composites

The co-deposition of PdO particles with a Cu matrix has been investigated with the aim of extending the composite deposition procedure to the preparation of materials potentially capable of catalyzing the low-temperature combustion of methane and other low hydrocarbons. Cu+PdO composites with a low dispersed phase content were obtained from either basic pyrophosphate or acid sulfate baths. PdO incorporation in Cu-Pd alloy matrices was much more effective than incorporation in Cu matrices, yielding deposits with 20-25 Pd at %, even when the Pd content of the alloys was as low as 1-2 at %. (Cu-Pd)+PdO composites were highly porous and mechanically stable.

Synthesis of Nickel-Carbon Nanohorn Composite Films by an Electrodeposition Technique

In this work, electrodeposition of nickel-single walled carbon nanohorns composite is obtained from a sulfamate bath. Electrodeposition of nickel-nanohorn composites is carried out from a sulfamate bath containing up to 2 g/l of dispersed single walled nanohorns with diameter 30 to 50 nm. Deposits with embedded nanohorns, homogeneously dispersed in metal matrix, are obtained. Structure of the deposits and contents of carbon nanohorns particles in these layers were investigated with respect to the possibility of agglomeration of SWNH particles and bath composition (concentration of SWNH in the electrolyte). Morphology of the coatings and the effects of codeposited particles on metal matrix structure are also reported. Microhardness of the composites has been investigated: Martens hardness is highly influenced by the incorporation of particles.

Pulse electrodeposition of Ni/nano-TiO2 composites: effect of pulse frequency on deposits properties

Pure and composite nickel deposits containing nano-TiO2 particles (dm = 21 nm) were produced under direct-DC and pulse current-PC conditions. The influence of pulse frequency on the codeposition of TiO2 particles, preferred orientation of Ni crystallites and grain size, as well as microhardness of the composites, was investigated systematically. Composites prepared in PC regime displayed higher incorporation percentage than those obtained under DC conditions, and the highest incorporation rates were achieved at pulse frequencies ν > 100 Hz. The application of pulse frequency accompanied by the embedding of TiO2 nanoparticles in the nickel matrix resulted in a strong influence upon the crystalline orientation, the grain size and the corresponding microhardness. All composites exhibited higher microhardness values compared to the pure deposits, independent of the applied current conditions. Overall, when ascribing the observed strengthening effect of composites, not only grain refinement and dispersion strengthening mechanisms but also preferred crystalline orientation should be taken into consideration.

Electrochemical behavior of low phosphorus electroless Ni–P–Si 3N 4 composite coatings

In the present investigation the electroless Ni–P–Si 3N 4 composite coatings were prepared by using a low phosphorus bath containing submicron size silicon nitride particles. Plain Ni–P deposits were also prepared for comparison. The phosphorus contents present in electroless plain Ni–P and Ni–P–Si 3N 4 coatings are 3.7 and 3.4 wt.%, respectively. Scanning electron microscope (SEM) images obtained for composite coatings (cross-sections) showed that the second phase particles are uniformly distributed throughout the thickness of the deposits. It was found that nodularity increased with particle codeposition in Ni–P matrix. To find out the electrochemical behavior of plain Ni–P and composite coatings, potentiodynamic polarization and electrochemical impedance (EIS) studies were carried out in 3.5 wt.% sodium chloride solution in non-deaerated condition. Second phase particle incorporation in Ni–P matrix indicated a marginal decrease in corrosion current density compared to the plain Ni–P deposits. This was further confirmed by EIS studies and SEM analysis of the corroded samples.

Effect of surfactant on the co-electrodeposition of the nano-sized ceria particle in the nickel matrix

Abstract The nickel–ceria (Ni–CeO2) nanocomposite coatings have been pulse electrodeposited from a Watts-type electrolyte containing nano-sized CeO2 particles produced by high-energy ball milling technique (HEBM). Sodium Lauryl Sulphate (SLS) has been added in the electrolyte as a cationic surfactant. The effects of the surfactant on the zeta potential, co-deposition and distribution of ceria particles in the nickel matrix and hardness of composite coatings have been investigated. Experimental results show that the addition of SLS up to 0.10 g/l increases the amount of co-deposited ceria particles in the nickel matrix and microhardness of the nanocomposite. However, when the amount of SLS in the electrolyte is more than 0.1 g/l, there is a tendency to form agglomerates of ceria particles in the nickel matrix resulting no further increase in hardness of the Ni–CeO2 nanocomposite coatings.

Semi-finished material and semi-solid forging of SiC particle reinforced al-mg light metal matrix composites – new results on process development and characterisation

Particle reinforced light metal matrix composites (MMC) were manufactured by thermal spraying of semi-finished material (atomisation and co-deposition of reinforcement particles and metal melt), followed by inductive reheating and semi-solid forging. The matrix alloy was Al Mg3, silicon carbide was used as particulate reinforcement. Semi-finished material processing was optimised regarding particle size and temperature distribution during material deposition in order to obtain a suitable microstructure for subsequent semi solid processing. Twin wire electric arc spraying with cored wires was applied, providing the matrix and reinforcement materials at the same time for simultaneous deposition. Process analysis was made by in-flight particle diagnostics. Semi-solid processing ability of the MMC material after thermal spraying was verified by manual deformation testing. Inductive reheating of the particle reinforced material was coupled with fast semi-solid forging by an axial press into a closed, plate-shaped die. Optical and Scanning Electron Microscopy showed some inhomogeneity in the SiC particle distribution. However, mechanical properties from tensile and 4-point bending experiments were encouraging.

Simple Model for Co-deposition of Oxide Particles with Zn

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Heat Treated NiP–SiC Composite Coatings: Elaboration and Tribocorrosion Behaviour in NaCl Solution

Tribocorrosion behaviour of heat-treated NiP and NiP–SiC composite coatings was investigated in a 0.6 M NaCl solution. The tribocorrosion tests were performed in a linear sliding tribometer with an electrochemical cell interface. It was analyzed the influence of SiC particles dispersion in the NiP matrix on current density developed, on coefficient of friction and on wear volume loss. The results showed that NiP–SiC composite coatings had a lower wear volume loss compared to NiP coatings. However, the incorporation of SiC particles into the metallic matrix affects the current density developed by the system during the tribocorrosion test. It was verified that not only the volume of co-deposited particles (SiC vol.%) but also the number of SiC particles per coating area unit (and consequently the SiC particles size) have made influence on the tribocorrosion behaviour of NiP–SiC composite coatings.

Sliding wear behaviors of electrodeposited Ni composite coatings containing micrometer and nanometer Cr particles

Micrometer and nanometer Cr particles were co-deposited with Ni by electroplating from a nickel sulfate bath containing a certain content of Cr particles. Cr microparticles are in a size range of 1–5 μm and Cr nanoparticles have an average size of 40 nm. The friction and the wear performance of the co-deposited Ni-Cr composite coatings were comparatively evaluated by sliding against Si 3N 4 ceramic balls under non-lubricated conditions. It is found that the incorporation of Cr particles enhances the microhardness and wear resistance of Ni coatings. The wear resistance of Ni composite coating containing Cr nanoparticles is higher than that of the Ni composite coating containing Cr microparticles with a comparable Cr particle content. The co-deposition of smaller nanometer Cr particles with Ni effectively reduces the size of Ni crystals and significantly increases the hardness of the composite coatings due to grain-refinement strengthening and dispersion-strengthening, resulting in a significant improvement of wear resistance of the Ni-Cr nanocomposite coatings.

Pulsed electrodeposition and characterization of bronze-graphite composite coatings

Composite coatings containing self-lubricant particles like graphite, MoS 2, PTFE are extensively used to decrease the coefficient of friction of tribo-surfaces. The aim of this study is to investigate the effect of pulse electrodeposition parameters on particle codeposition process and characteristics of bronze-graphite composite coatings electrodeposited from cyanide-stannate bronze electroplating bath. Results showed a slight increase in tin content and a promising increase in hardness of bronze coating by a decrease in duty cycle at constant average current density. Both tin content of the coating and grain refinement seem to participate in hardness enhancement. By increasing the agitation rate, an increase in graphite content of composite coating is observed followed by a decrease by further increasing of agitation rate. Keeping the average current density constant at 10 mA cm − 2 , graphite content of the coating is increased from 4% vol. to 18% vol. by decreasing the duty cycle from 1 to 0.05. The results showed that with an increase in graphite content of the coating, hardness and coefficient of friction of the coating would decrease and the lowest friction coefficient was obtained at 12% vol. graphite.

Codeposition of SiC particles with electrolytic cobalt in the presence of Cs + ions

Electrodeposition of SiC particles with cobalt matrix in the presence of cesium ions was studied. The influence of Cs + concentration (0–37.6 mM) on the cathodic polarization curves was determined in galvanostatic and potentiodynamic measurements. It was found that the presence of Cs + in the solution enhanced adsorption of Co 2+ ions on SiC, but preferential cesium adsorption occurred simultaneously. The last phenomena resulted in cesium incorporation in the composite coating. Surface charge of SiC powder and amounts of functional groups on SiC surface were determined. The particles incorporation into deposits was only little dependent on cesium concentration in the bath. Structure of the composite coatings was studied by microscopic observations. Microhardness of the deposits was also determined.

Electrodeposition and tribocorrosion behaviour of ZrO2–Ni composite coatings

With the objective of producing new functional surfaces with enhanced tribo-corrosion properties we have investigated the electrochemical codeposition of composites in which an electrodeposited metal (nickel) is the matrix and a transition metal oxide (ZrO2) is the dispersed phase. This paper describes the effect of ZrO2 dispersed particle codeposition on nickel electrocrystallisation steps as well as the tribocorrosion behaviour of the composite coatings obtained. This system was selected because nickel is an industrially important coating material on steel and other support materials. The cathodic polarization curves have been plotted both in the presence and absence of the insoluble dispersed phase. Electrochemical impedance spectroscopy was used to obtain additional information on the early steps of nickel and nickel matrix composite electrodeposition. Impedance data were acquired with a Solartron type electrochemical interface and frequency response analyzer. A schematic codeposition mechanism is proposed. The influence of zirconium oxide on the nickel electrodeposition steps is discussed. The tribocorrosion properties of ZrO2–Ni composite coatings (100 μm thickness) have been studied in 0.5 M K2SO4 solution on a pin on disc tribo-corrosimeter connected to an electrochemical cell. The normal force applied was 10 N at a rotation speed of 120 rpm. The counterbody (pin) was a corrundum cylinder (7 mm in diameter), mounted vertically on a rotating head, above the specimen. The lower spherical end (radius = 100 mm) of the pin was then applied against the composite surface (disc).

Advanced nanocomposites for high temperature aero-engine/turbine components

This paper provides a report on the research and development work contributing to the co-deposition technique used in the production of nanocomposite coatings by embedding sub-micron (nano-sized) particles into a nanometal matrix by electrodeposition. Electrolytic co-deposition is a technique used to produce composites by embedding small and large particles into the metal matrix during plating; this allows co-deposition of particles with improved properties and is extremely cost-effective. The resistance of a coating to high temperature oxidation and corrosion depends on its structure and composition; also on its interaction with the metal matrix and the corrosion environment. The nanoparticles are expected to pin the grain boundaries and prevent grain growth at high temperatures, e.g., 1,400°C for Ni turbine blades. The electrolytic composites were characterised using SEM. Industrial gas turbine blade (aerospace) has been successfully coated with these nanocomposites as overlay coatings. The focus of this study is primarily in the application of nanocomposites in industrial turbines/aero-engine components and power generation industry. The current state of knowledge of nanocomposite production is presented.

Electrophoretic deposition of hydroxyapatite–CaSiO 3–chitosan composite coatings

Electrophoretic deposition (EPD) method has been developed for the fabrication of hydroxyapatite (HA)–CaSiO 3 (CS)–chitosan composite coatings for biomedical applications. The use of chitosan enabled the co-deposition of HA and CS particles and offered the advantage of room temperature processing of composite materials. The coating composition was varied by the variation of HA and CS concentrations in the chitosan solutions. Cathodic deposits were obtained as HA–CS–chitosan monolayers, HA–chitosan/chitosan multilayers or functionally graded materials (FGM) containing HA–chitosan and CS–chitosan layers of different composition. The thickness of the individual layers was varied in the range of 0.1–20 μm. The deposition yield was studied at different experimental conditions and compared with the results of modeling. It was shown that the moving boundary model for the two component system can explain the non-linear increase in the deposition yield with increasing HA concentration in chitosan solutions. The obtained coatings were studied by thermogravimetric analysis (TGA), differential thermal analysis (DTA) and scanning electron microscopy (SEM). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies showed that these coatings provided corrosion protection of stainless steel substrates in Ringer's physiological solution. The deposition mechanism and kinetics of deposition have been discussed.

비수용액 전해질에서 전기도금한 니켈-TiO2복합 도금층의 표면 및 광분해 특성 연구

Composite plating is a method of co-deposition of plating layer with metallic and/or non-metallic particles to improve the plating layer properties such as high corrosion resistance and photolysis of organic compounds. The properties of nickel-ceramic composite plating are significantly depend on the surface characteristics of co-deposited particles as well as the quantity in electrolyte. In this study, Ni-<TEX>$TiO_2$</TEX> composite coating layer was produced by electrodeposition technique from non-aqueous eletrolyte and its surface characteristics as well as photolytic properties were investigated. The amounts of immobilized <TEX>$TiO_2$</TEX> particles increased with increasing the initial <TEX>$TiO_2$</TEX> particles contents in the bath. Samples electroplated with the current density of <TEX>$0.5\;A/dm^2$</TEX> showed the significantly improved homogeneous <TEX>$TiO_2$</TEX> particles distribution. The corrosion resistance of Ni-<TEX>$TiO_2$</TEX> composite coating layer also improved with increaing the amounts of <TEX>$TiO_2$</TEX> particles. Etched sample showed about 10% increased photolytic rate of organic matter compare to that of the non-etched.

Electrocodeposition of magnetic nickel matrix nanocomposites in a static magnetic field

The effect of an external magnetic field on the electrocodeposition of composites consisting of either Co or magnetite nanoparticles in a Ni matrix has been studied. An alkaline Ni pyrophosphate bath containing citrate was used. The magnetic particles were prepared by thermal decomposition (Co) or chemical precipitation (magnetite) and characterized by transmission electron microscopy, X-ray diffraction, dynamic light scattering, zeta potential and vibrating sample magnetometry measurements. The particle incorporation showed a distinct dependency on the orientation of an externally applied magnetic field. While the particle incorporation increased in a perpendicular field (perpendicular with regard to the electrode surface), it decreased in a parallel orientation. This result is explained with the dominating action of the magnetophoretic force. The structure and the properties of the Ni layers were significantly affected by the particle codeposition. A refinement of the Ni grains was found with increasing plating current density and as a result of the nanoparticle incorporation. The magnetic hardness and the Vickers microhardness of the films increased significantly due to the incorporation of the nanoparticles.

Electrochemical study of codeposition of Al particle—Nanocrystalline Ni/Cu composite coatings

Nanocrystalline Ni/Cu alloy matrix–Al metal particle composite coatings have been successfully developed via sediment codeposition (SCD) method. As high as 29 vol.% Al particles could be incorporated in the nanocrystalline Ni/Cu alloy matrix which has an average grain size of 16 nm. Adding conductive Al particles in the electrolyte shifted polarization curves to more negative potentials, which is a characteristic of electro-codeposition of nonconductive particles. The codeposition behavior has also been found to be consistent with the Guglielmi's model that was proposed for predicting the codeposition of nonconductive particles in metal matrix.

Influence of surface properties of ceramic particles on their incorporation into cobalt electroless deposits

The purpose of this work was to elucidate factors affecting electroless codeposition of metal with ceramic particles. Codeposition of various particles with Co-P in an alkaline solution was compared. Powders of SiC, Al 2O 3 and SiO 2 were used. It was found that surface properties of the technical powders were different from that reported for materials of high purity. Codeposition of SiC was favored by a positive surface charge of the particles, while negative surface charges of alumina and silica inhibited their embedding. The positive surface charge of SiC particles corresponded to low adsorption of cobalt ions and increased adsorption of hypophosphite anions, while opposite dependencies for alumina and silica were observed.