Adhesion behavior of APC-2/AS4 PEEK/Graphite composite has been studied by varying the surface preparation techniques such as acetone washing, grit blasting and several plasma gas etching treatments. Poly(imide-siloxane) segmented copolymer prepared in our laboratory and Ultem® 1000 were utilized as adhesives. Single lap shear samples were prepared from the PEEK/Graphite composite and compression molded adhesive films. Excellent single lap shear strength values were obtained at room temperature. The morphology and elemental change by surface preparation of the adherend were monitored by scanning electron microscope(SEM) and x-ray photoelectron spectroscopy(XPS). Plasma etch treatments were effective for improving the adhesion characteristics.

RF stimulated DC discharge mode was developed and used in plasma anodization. Equipment operating in this mode has been set up for anodizing semiconductor materials. To improve the feature of this equipment, enhanced electrode was induced. Anodized oxide film of silicon was applied as gate oxide film in MOSFETs on SOI structure. This paper describes this discharge mode and enhanced electrode and give the properties of the oxide film and MOSFETs.

Simulation of if discharges through numerical solutions to the Moments of the Boltzmann Transport Equations (MBTE) is discussed. Continuity and momentum equations for the electrons and ions, and electron energy equation have been solved using an efficient finite difference scheme. Results for a 13.56 MHz argon discharge are presented.

A plasma-enhanced organometallic chemical vapor deposition (PE-OMCVD) has been studied as an alternative plasma process to prepare high Tc superconducting thin films. Metal β–diketonates such as Y(fod)3, Ba(hfa)2 and Cu(hfa)2 were decomposed by Ar/O2 plasmas produced with an applicator type microwave discharge system. Optical emission spectroscopy was used to monitor radical species during vaporization and decomposition of the source materials. The YBaCuO films grown on substrates(MgO, SrTiO3 and c-Si) showed amorphous structure. After the post-annealing, the films exhibited an x-ray diffraction pattern with c-axis perpendicular to the substrate and showed an onset superconducting transition temperature of 87 K. The PE-OMCVD process provided high film deposition rate of 30–120 nm/min.

In order to control reactive silane(SiH4) glow discharge plasmas for an a-Si:H thin film synthesis, we have investigated the dependence of plasma parameters on the crossed magnetic field B perpendicular to the discharge electric field E. As the result of modification of plasma structure by a crossed magnetic field, subsequent modified profiles of optical emission from SiH radicals were observed. On the other hand, Hα, emission in the cathode sheath region, which may be caused by high energy secondary electrons(γ-electron), were not so much influenced by a magnetic field. By modulating the crossed magnetic field in AC discharge plasmas, the time-averaged uniform (2.5% inhomogeneity) profile of SiH radical could be realized near the substrate sustained outside the discharge region.

Increased demands of the aircraft jet engines have been steadily increasing the need for materials exhibiting higher strength at high temperatures. Ni-base alloys, which are highly resistant to thermal fatigue and thermal shock have been used to meet these requirements. Ni-base alloys, known for their high temperature strength up to 900°C, were deposited by the vacuum plasma spray (VPS) process. The plasma deposition process uses metal powders, offering near net shape capability with dense and homogeneous microstructures. The research described here reviews the properties of several Ni-base alloys: Ni5Mo5Al, Ni27Mo6Al and blends with Mo powders, consolidated by the VPS process. These Ni-base metals which are alloyed or blended with Mo have lower thermal expansion than the common used materials alloyed with chromium. These metals were deposited using plasma jets, varying the operational parameters and conditions. The morphology of the powder particles of the alloys has been studied prior to processing. The microstructures of the deposits were analyzed in the “as-sprayed” conditions and after post deposition treatments. Plasma deposition parameters were selected which produced dense as-sprayed structures up to 98%. Post deposition thermal processes such as HIP and sinter cycles were also explored. The deposited materials were analyzed for the degree of particle melting in the jet, deposit bulk density, mechanical properties (tensile and impact) at room temperature and at 760°C and coefficient of thermal expansion from R.T to 1100°C. Results showed that the VPS process and post deposition treatments produced dense (˜99%) Ni-alloys deposits with high strength and low coefficients of thermal expansion.

Plasma sprayed ceramic coatings are mainly used for the protection of metal components in diesel engines, gas turbines and aeroengines. Increasing demands for better thermomechanical properties at higher temperatures require well defined and reproducible spraying conditions. The way the powder is manufactured plays an important role in the quality of the coatings. This paper presents a study carried out on three grades of zirconia powders manufactured by different processes. The heat treatment of the powders has been monitored within the plasma jet by in flight pyrometry and laser velocimetry. The particulates melting is controlled by observation of individual particulates splats collected on glass slides. A mathematical model of plasma particulates heat transfer allows to explain the obtained results.

The concentration and temperature of air entrained into an argon plasma jet have been measured using coherent anti-Stokes Raman spectroscopy (CARS). The flow field is characterized by a short region of well behaved laminar flow near the nozzle exit followed by an abrupt transition to turbulence. Once the transition to turbulence occurs, air is rapidly entrained into the jet core. The location of the transition region is determined by the rapid cooling of the jet and the resulting increase in Reynolds number.

A mathematical formulation is presented to describe the interaction between a plasma and injected particles. In the formulation, a realistic allowance is made for intraparticle conduction, vaporization and non-continuum effects. The theoretical predictions are compared with experimental measurements and quite reasonable agreement has been obtained. A discussion is presented assessing the relative importance of the various factors that govern plasma-particle interactions.

Experimental measurements and computed results are reported, describing the behavior of a non-transferred arc plasma torch operating in a laminar mode, discharging into a nitrogen environment. The experimental measurements of the temperature fields in the vicinity of the torch exit, obtained using emission spectroscopy, were compared with theoretical predictions. The calculations were based on the solution of the axi-symmetric heat, mass, momentum, and species balance equations. The theoretical predictions were found to be in excellent agreement with measurement, with the error usually being in the 5–10% range and the maximum error being about 15%.

The distribution of Al2O3 particle size, velocity and temperature was mapped over the flow field of a 31.5 kW plasma torch. The effects of varying the powder loading were studied. The powder feed rate was varied between.45 and 2.05 kg/hr independent of the carrier gas flow rate. The particle flow field was non-symmetric due to the method of particle injection. The data indicate that powder feed rate does not significantly affect either the temperature or velocity of the particles, for typical plasma spray conditions, and that the assumption of a dilute particle flow field is valid.

A mathematical representation is developed to describe heat and fluid flow phenomena inside the plasma torch for a non-transferred arc system. In the model a joule heating pattern is postulated for the arc column and then the heat flow and fluid flow equations are solved rigorously. The resultant solutions give information on the temperature and the velocity fields in the plasma gas inside and outside the torch. By postulating “reasonable” values for the heat generation pattern, very good agreement has been obtained between measurements and predictions for a laminar system, used by the INEL researchers. The agreement was less satisfactory with measurements obtained using a Metco torch, where the flow was turbulent. These findings indicate that this is a promising avenue for research, but a great deal more needs to be done before a model of general validity can be developed.

A general method for the analysis of the thermal stresses of plasma-sprayed thermal barrier coatings is presented. It employs a simulation technique for the reproduction of the microstructural data. Homogenization theories are used, in conjunction with symbolic analysis, in order to obtain a piece-wise homogeneous effective representation of the coating, starting from these data. The temperature portrait and the thermo-elastic fields are numerically obtained.

The key parameters controlling the thermomechanical properties of plasma sprayed coatings (d.c. plasma spraying) are the heat and momentum transfers between the plasma jets and the injected particles. These, beside the particles size and injection velocity distributions as well as the plasma gas nature, depend strongly on the plasma isotherms lengths and diameters which in turn are controlled by nozzle, arc chamber and plasma gas injector designs. This paper is devoted to the study of these last parameters for Ar-H2 and Ar-He plasma jets flowing in air or in controlled atmosphere chambers filled, at atmospheric pressure, with nitrogen or argon. After a brief description of the working principle of d.c. spraying plasma torches (thoriated tungsten cathode, stick type) and of the experimental set ups (automatized emission spectroscopy and energy balance of the plasma torch) are presented successively the influence of: - the gas injection close to the cathode tip on the plasma jet behaviour - the gas injector design on the plasma jet isotherms lengths and diameters - the gas nature (Ar-H2 or Ar-He) and the surrounding atmosphere on the same parameters.

PECVD oxides are promising as low-temperature gate insulator for MOS devices. For the evaluation of their quality, PECVD oxides of 10nm–35nm are deposited by using different RF power frequencies (100KHz, 450KHz or 13.56MHz), a low plasma energy density (0.04W/cm2) and a mixture of He, N2O, SiH4 gases. The deposition is followed by a set of RTP anneals at different temperatures. After aluminium metallization and gate definition, C(V)- and FN-characteristics are measured. Interface trap densities, oxide charge densities, breakdown fields and breakdown charges are determined.

A comparative study is made of CH4:H2 and CH3−CH3:H2 metal-organic reactive ion etching of molecular beam epitaxially grown GaAs. The etch rates are measured to be proportional to both CH4 and CH3−CH3 concentrations, with empirically determined order of reactions at 1.1 W.cm−2 of, 0.57 ± 0.1 and 0.32 ± 0.01. Approximately twice the number of CH4 molecules are required to produce the equivalent etch rate as CH3−CH3 molecules. The measured apparent activation energies are low, Ea ≤ 6 meV, and GaAs area loading effects are the same. These results indicate that methyl radicals are predominately responsible for the reaction.

Crystal damage of GaAs(100) caused by Reactive Ion Etching (RIE) using a mixture of Cl2 and Ar gas has been assessed using Surface Roughness (Ra), Resonant Raman Spectroscopy (RRS), Schottky diodes, and Spectroscopic Ellipsometry (SE). Plasma conditions for minimum induced damage have been determined and compared to optimised RIE processes using plasma gases SiCl4, CH4-H2, CCl2F2 and Ar. The SiCl4 plasma was found to produce the least crystal damage.

New DC bias method for the electron cyclotron resonance (ECR) plasma chemical vapor deposition (CVD) is demonstrated, where the highly photosensitive a-Si:H film of the device grade is deposited on the dielectric substrate. The measurement of plasma parameters using a probe technique indicates that the impinging of ion H+ on the growing surface is the key to the high quality a-Si:H film and this DC bias method controls the film properties by the ion density rather than the ion energy.

The reaction kinetics of Remote Plasma-enhanced Chemical Vapor Deposition (RPCVD) have been studied using Langmuir probe measurements of plasma density and plasma potential combined with growth rate data as a function of r-f power, chamber pressure, and substrate bias. An observed increase in growth rate for negative substrate bias suggests that argon ions drive the reaction. The variation of ion density, and plasma potential with r-f power suggests that the flux of argon ions, not their kinetic energy is responsible for increased growth rates at higher r-f powers.

The fabrication of devices in high-temperature superconducting ceramics will require the development of suitable techniques for patterning thin films of these materials. We report the plasma etching of Y-Ba-Cu-oxide thin films using techniques adapted from the semiconductor industry. The etching reactor consists of a dc hollow cathode discharge using a chlorine/helium mixture as the working gas. The Y-Ba-Cu-oxide films are deposited on alumina substrates using ion-beam sputtering. We have investigated the etching of these films over a broad range of gas pressures, substrate temperatures, and input powers, using both as-deposited and oxygen annealed films. Substrates were held at ground potential to minimize ion bombardment during etching in order to separate the chemical aspects of the etching process from ion-bombardment effects. The etch rate of these films was found to be highly dependent on the substrate temperature, the system pressure, and on whether the films are annealed. Annealed films etch nearly an order of magnitude more slowly than unannealed films. The film stoichiometry, measured using energy dispersive spectroscopy (EDS), varies greatly with temperature. The copper in the films is removed at the lowest temperature, followed by barium and then yttrium.