Multilayered coatings of single and dual particle metal matrix composites, with or without ceramic overlayers, have been produced by a novel combination of electrochemical deposition (electroplating and electrophoretic deposition) and reaction bonding. The coatings contain the following layers in a variety of combinations deposited on Ni substrates: (i) electroplated composites of Ni with Al and/or alumina particles, (ii) precursor Al + A12O3 + yttria stabilized ZrO2 transformed into A12O3 + yttria stabilized ZrO2 by the reaction bonding method, and (iii) yttria stabilized ZrO2. In order to determine the appropriate processing parameters for the multilayered coatings, uniform one-layer coatings were deposited and characterized. We find that in the dual particle Ni-Al-Al2O3 coatings the volume percent of the particles does not show a dependence on deposition current density. However, volume percent alumina in these coatings has a strong dependence on the amount of this particle in the plating bath, while the volume percent Al shows only a weak dependence on its bath content. Comparison of the deposition behavior of these dual particle with single particle coatings, containing Al or alumina only, reveals that the presence of Al in the bath interferes with the codeposition of alumina. This interference, however, is not reciprocal. When coatings containing Al are annealed, Ni and Al react to form a solid solution of Al in Ni (γ) or a two phase mixture of this solid solution and the intermetallic, Ni3Al, (γ-γ') depending on the annealing temperature. Finally, we find that the formation of the reaction bonded alumina plus yttria stabilized zirconia layer requires the oxidation resistance afforded by aluminum in the underlying electroplated layer.

This article involves the study of the electrodeposition of composite coatings that form when colloidal particles deposit onto an electrode at which metal electrodeposition simultaneously occurs. The codeposition process of polystyrene (PS) and polymethylmethacrylate (PMMA) particles from a copper plating bath on a rotating disk electrode (rde) was investigated both theoretically and experimentally. The influence of the fluid flow velocity, density, mean size and zeta-potential of the particles, viscosity and temperature of the plating bath on the deposition rate of particles is studied using the theoretical model. The predictions of the model are compared with experimental results.

The formation and characterization of composite films of copper/boron nitride (Cu/BN) and nickel/boron nitride (Ni/BN) are described. Composite Cu/BN and Ni/BN films were synthesized by a metal electrodeposition from suspensions of boron nitride particles on carbon steel substrates. The effects of concentration of boron nitride in the solution, temperature, potential and various additives on the morphology of composite films have been investigated. The morphology of these films was examined using Scanning Electron Microscopy. The elemental analysis for boron, nitrogen, copper and nickel was performed using Energy Dispersive X-ray Spectroscopy (EDS), and a Microprobe X-ray Analyzer. The Vickers hardness of Cu/BN and Ni/BN films prepared under different conditions was also investigated. It has been found that the composite Cu/BN and Ni/BN films have an increased microhardness as compared to the respective pure metal films. The effects of deposition potential, temperature, concentration of BN and presence of various additives on the microhardness of Cu/BN and Ni/BN films have been investigated.

In this study, electrodeposition was employed to produce Cu-Ag multilayered nanocomposites using a single-bath cyanide solution. The silver and the copper layers were applied by electroless deposition and galvanostatic electrodeposition methods, respectively. The as-deposited composite showed a very high strength, which was increased upon annealing at 104°C. Annealing at 149°C caused the strength to drop to a level comparable to the strength of electrodeposited pure copper specimens. In this paper, the effect of heat treatment on the mechanical properties and structure of Cu-Ag multilayered nanocomposites is discussed.

Amorphous Fe80B20 alloy films with a large quantity of plastics (polymethyl methacrylate: PMMA) are prepared using a combined technique of electrochemical plating and spin coating. The embedding of amorphous alloys into PMMA plastics is expected to reduce the effective conductivities of alloy films, and hence to improve their magnetomechanical coupling coefficients at high frequency by reducing effective eddy-current losses. Preparation conditions for obtaining Fe100−XBX (X=20±5at%) films with amorphous structure are determined, and the composite films are formed in accordance with the plating conditions. The resultant composite films are studied by examining their surface states and magnetic properties.

Electrolytically deposited nanocrystalline Ni-45%Fe alloys, composed of γ (f.c.c.) phase, were annealed at 573 and 673 K for time periods up to 20 h in an inert atmosphere of argon. The evolutions of crystallographic texture, grain size, and microhardness were analyzed as a function of annealing parameters. The initial grains, approximately 5 nm in size increased after annealing up to 10–20 nm, however, the growth kinetics and the final grain size depended on the temperature. A correlation was found between the grain size and alloy microhardness. The phase composition was unstable and during annealing the α(b.c.c) phase was detected to precipitate from the γ matrix. The texture of γ phase, consisted of two fibre components of <111> and <200>, and evolved at high temperatures. Although the detailed changes depended on the annealing temperature, in general, the <111> component became stronger at the expense of the <200> component.

The electrodeposition of copper on composite conductive polymer polypyrrole/polystyrenesulfonate PPy(PSS) has been studied. The morphology of copper deposits was investigated in the presence of thiourea and other additives. It has been found that in the presence of thiourea in the solution, the rate of copper deposition on a PPy(PSS) substrate is slightly inhibited but the rate of copper stripping is faster than in its absence. The Electrochemical Quartz Crystal Microbalance (EQCM) technique allowed us to simultaneously monitor voltamperometric and resonance frequency vs. potential or time characteristics. The amount of electrodeposited copper was controlled by monitoring the EQCM resonant frequency. Composite PPy(PSS) films functioning as cation-exchange membranes were used as substrate materials for metal deposition. They allowed us to electrodeposit copper not only on the surface of the conductive polymer but also inside the polymer matrix. The size of copper nanocrystals formed inside the polymer was controlled by the applied electrode potential. Copper crystals as small as 20 nm were detected with Transmission Electron Microscopy (TEM).

An excimer lamp is a new light source which can produce shorter wavelength of vacuum ultraviolet radiation than conventional ArF excimer lasers. We have tried to use the excimer lamp for photo-etching of polymers such as polymethylmetacrylie and polyimidic resins. We have found that the etching process was including the chemical and the quantumn processes. We also applied this technique for etching of some single crystalline organic materials which were very important to opt-electronic applications.

A Fluorocarbon resin surface was selectively modified by irradiation with a ArF laser beam through a thin layer of NaAlO2, B(OH)3, or H2O solution to give a hydrophilic property. As a result, with low fluence, the surface was most effectively modified with the NaAlO2 solution among the three solutions. However, the contact angle in this case changed by 10 degrees as the fluence changed only 1mJ/cm2. When modifying a large area of the surface, high resolution displacement could not be achieved because the laser beam was not uniform in displacing functional groups. Thus, the laser fluence was successfully made uniform by homogenizing the laser beam; the functional groups were replaced on the fluorocarbon resin surface with high resolution, which was successfully modified to be hydrophilic by distributing the laser fluence uniformly.

Large area surface modification of fluorocarbon resin was performed by ArF laser beam irradiation, and water or B(OH)3 solution for its practical application. To complete treatment in a short time and keep its cost lower, the total amount of photons that induce reactions was reduced by decreasing the laser fluence as well as shot number. Water or B(OH)3 was sandwiched between a fused silica glass and a fluorocarbon resin film to form a thin layer using a capillary phenomenon. The substrate was perpendicularly irradiated with ArF excimer laser through a cylindrical lens. By moving horizontally, the surface was continuously modified. The extensively modified sample was mounted to stainless steel with epoxy resin, and the tensile strength was measured. As a result, the adhesive strengths of the sample modified with water and the one with B(OH)3 solution improved 275 and 490 times that of the untreated sample respectively.

A thin layer of water or hydrogen peroxide solution, which was formed on a pure aluminum substrate, was photodissociated by ArF excimer laser( λ =193nm) or Xe2* excimer lamp (λ = 172nm) light to photochemically oxidize the surface of aluminum substrate. The layer was formed by a capillary phenomenon between the substrate and a fused silica glass as an entrance window of ultraviolet light. Then, the layer was photodissociated by the excimer laser or the excimer lamp light irradiation to generate active oxygen; the surface oxidization was performed by the photo-induced active oxygen. The surface before and after modification was evaluated by the XPS analysis; the high densed photo-oxidization film was confirmed on the modified surface, compared with a natural oxidization film Furthermore, the contact angle with water became remarkably small, and it is seen that the treated surface was quite densely oxidized.

Corrosion of thin film structures commonly used in electronic and magnetic devices is discussed. Typical failure modes are presented, and galvanic corrosion is discussed in some detail since it is one common problem with such devices. A graphical explanation for the determination of the ohmic potential drop during galvanic corrosion is presented. The corrosion problem of thin film disks is shown to have changed during the past ten years owing to changes in disk structure. The corrosion susceptibility of two antiferromagnetic alloys used for exchange coupling to soft magnetic layers is discussed.

An electrochemical atomic force microscope (ECAFM) has been employed to observe, in situ, the topographical and electrical changes that occur on 304 stainless steel as a function of an electrical potential. The concurrent acquisition of a polarization curve and topographical data allows direct correlation of variations in the surface roughness with the electrochemical characteristics of the passivation process. Also, the large AFM scan size, employed in this study, allows for the delineation and determination of the interdependence of the surface kinetics at various regions of the surface. Simultaneous measurements of topographical and electrical changes at these regions have established a correspondence of the competing kinetics between the reactions of dissolution and passivation. This provides a way to relate chemical surface reactions to surface topography.

The electrochemical reaction of polycrystalline MoxN (x=1 or 2) thin film electrodes in 4.4 M H2SO4 electrolyte has been investigated. The films were prepared by a temperature programmed procedure involving the reaction of MoO3, and NH3 The electrochemical voltage stability of these films in the electrolyte, referenced to a standard hydrogen electrode (SHE), was + 0.70 V (-0.01 to + 0.69). Below + 0.69 V, cyclic voltammetry and AC impedance spectroscopy indicated that MoxN electrodes were capacitive. However, above this value an electrochemical reaction of the MoxN films was observed. The formation of an amorphous phase in the reacted MoxN films was indicated by X-ray diffraction (XRD) patterns. Secondary ion mass spectroscopy (SIMS) detected the presence of hydrogen, oxygen, and sulfur. The voltage bias (+ or -) applied to the electrodes influenced the chemical composition of the reacted MoxN films.

Boron-doped diamond has been deposited over a Mo substrate by microwave plasma CVD using methane and hydrogen. Boron doping of diamond has been achieved in situ by using a solid boron source while growing the diamond. Impedance spectroscopy of diamond in 0.5 M NaCl solution has been studied. We have observed two time constants at the diamond/solution interface. Solution resistance was found to be constant irrespective of the electrode in the same electrolyte. DC polarization techniques such as linear and Tafel polarization have been used to evaluate the doped diamond/Mo and Mo for corrosion resistance characteristics interms of charge-transfer coefficients and corrosion rate. Cyclic voltammetry has been used to evaluate the doped diamond/Mo to study the background current response and the redox kinetics of ferri/ferrocyanide in 0.5M NaCl solution.

In the scheme for geological disposal of high level radioactive nuclear wastes, the burial pit is to be isolated from the sphere of human life by a multiple-barrier system, which consists of an artificial barrier, composed of a canister, an overpack and a bentonite cushioning layer, and a natural barrier, which is essentially the bedrock. As the greatest as well as essentially the sole detriment to its integrity would be corrosion by groundwater. The groundwater comes to it seeping through the bentonite zone, thereby attaining conceivably the pH of transition from general corrosion to passivity, pHd, the behaviors of mild steel in such a groundwater environment have been examined. It has been shown that the pHd is lowered (enlargement of the passivity domain) with rising temperature and carbonate-bicarbonate concentration, while it is raised (enlargement of the general corrosion region) with increasing concentrations of chloride and sulfate ions.

Anodization is effective for improving the corrosion resistance of aluminum-matrix composites. For SiC particle filled aluminum, anodization was performed successfully in sulfuric acid electrolyte, as usual. However, for AlN particle filled aluminum, anodization needed to be performed in an alkaline (0.7 N NaOH) electrolyte, because NaOH reduced the reaction between AlN and water, whereas an acid enhanced this reaction. The concentration of NaOH in the electrolyte was critical; too high a concentration caused the dissolution of the anodizing product (Al2O3) by the NaOH, whereas too low a concentration did not provide enough ions for the electrochemical process. The corrosion properties and anodization characteristic of pure aluminum, Al/AlN and Al/SiC were compared. Without anodization, pure Al had better corrosion resistance than the composites and Al/SiC had better corrosion resistance than Al/AlN. After anodization, the corrosion resistance of Al/AlN was better than Al/SiC and both composites were better than pure Al without anodization, but still not as good as the anodized pure Al.

The experiments described in this paper clearly show that Second Harmonic Generation (SHG) may be used as a sensitive tool for detecting oxide impurities at interfaces not accessible for usual surface characterization methods. As a striking feature, one peak in the temperature dependent SH intensity is observed for liquid potassium and five peaks for liquid cesium. The occurrence of these peaks cannot be understood in terms of the nonlinear optical properties of the pure metal. By varying the oxygen content present in the melt it can be shown that these peaks must be attributed to the presence of oxide impurities segregating at the interface. In addition it is shown that the presence of oxides at the interface inert sapphire - molten alkali metal significantly alters the structure of the sapphire surface finally leading to corrosion visible even by the eye.