Showing papers on "Oxide published in 1985"

Modification of the Electrochemical and Corrosion Behavior of Stainless Steels with an Electroactive Coating

Abstract: Electroactive polyaniline coatings have been deposited on ferritic stainless steels. The coatings appear to be deposited over the passive metal oxide film but can undergo electron transfer with the metal. Polyaniline immobilized on the alloys imparts a form of anodic protection which stabilizes the materials in mineral acids. Electrochemical and SEM characterization results are presented, and effects of coating application techniques are discussed. Oscillations in the open‐circuit voltage occur in solutions containing a high enough concentration of chloride ion to initiate pitting at potentials dictated by the coating. Inhibition of localized corrosion may also be obtainable for favorable systems.

A new model for upper and lower critical solution temperatures in poly(ethylene oxide) solutions

Abstract: Diagramme de phases du systeme PEO-eau calcule en utilisant la theorie de Flory; accord semi-quantitatif avec l'experience

The surfaces of metal oxides

Abstract: The author reviews the present understanding of the electronic, geometric and chemisorption properties of metal oxide surfaces. It is restricted to experimental and theoretical studies of single-crystal oxide surfaces since only for those systems has it been possible to correlate surface properties with specific site geometry, ligand coordination, defect structure, etc. The geometric structures of the oxide surfaces that have been investigated to date are described in relation to bulk crystal structure and cation ligand coordination. The electronic structure of both perfect and defect surfaces is discussed for the various classes of metal oxides, and similarities and differences in their behaviour are correlated with surface geometry and cation electronic configuration. The chemisorption of several types of atoms and molecules on single-crystal oxide surfaces, both nearly perfect and containing point defects is reviewed and interpreted in terms of surface electronic and geometric structure. Some recent electron- and photon-stimulated desorption results on oxides are also reviewed, as the measurements of surface phonon and plasmon modes.

Surface Composition of Stainless Steels during Anodic Dissolution and Passivation Studied by ESCA

Abstract: A molybdenum containing austenitic steel was exposed in hydrochloric acid at various potentials in the active and passive ranges of the alloys. The surface compositions were analyzed by the ESCA technique. The influence of pretreatment by ion bombardment and mechanical polishing on the passivation behavior was investigated. The passive film formed on the surface consists mainly of a mixed Fe‐Cr‐Mo oxide. The average content of Cr3+ in the oxide is about 70%. The inner layers of the oxide product consist mainly of Cr oxide. The Ni content in the oxide is low. The concentration and the chemical state of Mo is potential dependent. At low potentials in the passive range, the four‐valency state is predominant, while at high potentials Mo exists mainly in its six‐valency state. On the surface of the oxide, a layer of hydroxide is present. Chloride ions are incorporated into the passive film. The thickness of the passive film increases with the potential in the passive range from 10 to 15A. The composition of the metal phase changes during active dissolution. Thus, the alloying elements are enriched on the surface and thereby control the dissolution rate, control overpotentials, and provoke passivation of the alloy.

Early high-strength mineral polymer

Abstract: An early high-strength mineral polymer composition is formed of a polysialatesiloxo material obtained by adding a reactant mixture consisting of alumino-silicate oxide (Si 2 O 5 ,Al 2 O 2 ) with the aluminum cation in a four-fold coordination, strong alkalis such as sodium hydroxide and/or potassium hydroxide, water, and a sodium/potassium polysilicate solution; and from 15 to 26 parts, by weight, based upon the reactive mixture of the polysialatesiloxo polymer of ground blast furnace slag. Sufficient hardening for demolding is obtained in about 1 hour with this composition.

Boron Adsorption on Aluminum and Iron Oxide Minerals1

Abstract: Boron adsorption behavior was investigated on various crystalline and x-ray amorphous Al and Fe oxide minerals. Adsorption increased at low pH, exhibited a peak in the pH range 7 to 8, and decreased at high pH. The magnitude of B adsorption was much greater for the x-ray amorphous materials. Since B adsorbs specifically on Al and Fe oxide minerals, the constant capacitance model containing a ligand exchange mechanism was used to describe its adsorption behavior. The constant capacitance model was able to represent B adsorption on all minerals over the entire pH range studied (3-12) using the same set of surface complexation constants. With the exception of amorphous Al oxide, B adsorption on these oxide minerals could be successfully described by optimizing only the B surface complexation constant. Other nonexperimental parameters were held fixed at values identical to those previously used in modeling phosphate, silicate, and selenite adsorption on Al and Fe oxide minerals. Additional Index Words: anion adsorption, ligand exchange, surface chemistry, constant capacitance model. View complete article To view this complete article, insert Disc 4 then click button8

Preparation and characterization of rf sputtered indium tin oxide films

Abstract: Indium tin oxide films have been grown by rf sputtering at various Ar‐O2 mixtures, at low substrate temperatures (200 °C), and deposition rates (25 A/min), followed by post deposition annealing (at 350 °C) in different ambients (O2, N2, and cracked ammonia). Influence of a reactive gas (oxygen) on the sputtering rate of a metallic (indium/tin) alloy target has been investigated. Growth parameters and annealing conditions have been optimized. The films were characterized by electron and x‐ray diffraction, scanning electron microscopy, and transmittance as a function of wavelength. The effect of heat treatment in various environments on the structural, electrical, and optical properties has been investigated. Effect of a new annealing ambient, cracked ammonia (reducing atmosphere), on the reactively sputtered oxide films is being reported for the first time. Cracked ammonia was found to be very effective and cheap and resulted in films of high quality (electrical and optical) with good structural properties...

Ellipsometric study of anodic oxide films on titanium in hydrochloric acid, sulfuric acid, and phosphate solution

Abstract: The anodic oxide film on titanium has been studied by ellipsometry and SEM observation. Ex situ multiple‐angle‐of‐incidence and in situ ellipsometric measurements allow the complex refractive index to be estimated at for the titanium substrate and at for the anodic oxide film at wavelength 546.1 nm. The anodic oxide film thickness increases linearly with potential in a range from −0.55 to 7.5V (RHE) at the rate of 2.8 nm V−1 in phosphate solutions of pH 1.6–12.1, 2.5 nm V−1 in solution, and 2.4 nm V−1 in solution. At potentials more positive than 7.5V, the film breaks down, leading to the formation of a thick oxide film probably due to an increased ionic current through the breakdown sites. The film composition is estimated to be or , which suggests the presence of hydroxyl bridge in its bonding structure.

Manufacture of semiconductor device

Abstract: PURPOSE:To suppress the oxidation which makes progress in lateral direction through an oxide film when a selective oxidation is performed as well as to stop the generation of bird's beaks to the minimum by a method wherein the oxide film on an element forming region is coated by a nitride film and a semiconductor substrate CONSTITUTION:A nitride film 6 is formed by superposition on the oxide film 5 formed on the surface of a semiconductor substrate 1 as a pad oxide film Then, a photoresist film is formed on the nitride film of an element forming region using photoetching technique, the oxide film 5 and the nitride film 6 are removed by performing a dry etching in the gas of CF4+O2 using the photoresist film as a mask, and another etching is performed on the substrate again Then, after the photoresist used as a mask has been exfoliated, a nitride film of almost the same thickness as the nitride film formed previously is formed Then, a nitride film 10 is formed by performing a just etching on the nitride film 9 using the plasma etching device of CF4+O2 gas parallel flat plate leaving the side face of a semiconductor substrate 7 located under the oxide film 5' and another oxide film 5' on the element forming region, and a nitride film 10 is formed Then, a thick oxide film 11 can be formed on the area other than the element forming region by performing an oxidation using the nitride film 10 as the mask of selective oxidation

Method of treating teeth with certain photopolymerizable compositions including catalyst comprising an acylphosphine oxide

Abstract: A method of treating teeth with a photopolymerizable composition comprising at least one olefinically unsaturated monomer and an acylphosphine oxide catalyst.

Process for the vapor phase hydrogenation of carboxylic acids to esters and alcohols

Abstract: The vapor phase formation of carboxylic acid alcohols and/or esters such as ethanol and ethyl acetate from the corresponding mono and di-functional carboxylic acid, such as acetic acid, in the presence of a copper oxide-metal oxide supported catalyst, such as CuO/ZnAl 2 O 4 .

Rapid thermal processing of thin gate dielectrics. Oxidation of silicon

Abstract: A new rapid process for the growth of thin thermal oxide films on crystalline silicon is described. This rapid thermal oxidation (RTO) is performed in a controlled oxygen ambient with the heating provided by tungsten-halogen lamps. The resulting oxides with thicknesses from 40-130 A have a uniformity of better than 2 percent across the 75-mm wafers. Oxidation times at 1150°C vary from 5 to 30 s. Typical breakdown fields of 100-A oxide films were 13.8 MV/cm and typical midgap interface state densities were of the order of 1 × 1010eV-1cm-2. The present RTO films have characteristics equal to or better than furnace grown oxides and because of the short temperature-time cycle they have potential applications for submicrometer VLSI.

Physicochemical properties of rare earth perovskite oxides used as gas sensor material

Abstract: The change of the conductivity in the rare earth perovskite oxide took place after the chemisorption of flammable gases. The sensitivity for methanol was highest. From the conductivity change of these perovskite oxides after the injection of methanol, the energy needed to promote an electron from a conducting to a nonconducting state, ΔE=E c-E t, could be derived from the equationσ=A σ 0 exp (−ΔE/kT). LnCoO3 had the smallest ΔE and ΔH (metal-O), which is the binding energy of oxygen coordinating to the metal ions, but exhibited the highest activity for gas sensing. The gas sensing mechanism was also considered.

Catalyzed diesel exhaust particulate filter

Abstract: A self-cleaning diesel exhaust particulate filter is disclosed wherein burn-off of collected particulate matter is accomplished at certain exhaust gas temperatures, the filter being provided with a catalyst mixture consisting essentially of a platinum group metal and an alkaline earth metal oxide. The platinum group metal may be one or both of platinum and rhodium and the alkaline earth metal oxide may be magnesium oxide. The presence of the catalyst mixture serves to lower the temperature at which ignition of the collected particulates is initiated.

Silicon-on-insulator (SOI) by bonding and ETCH-back

Abstract: A silicon wafer bonding process is described in which only thermally grown oxide is present between wafer pairs. Bonding occurs after insertion into an oxidizing ambient. It is proposed the wafers are drawn into intimate contact as a result of the gaseous oxygen between them being consumed by oxidation, thus producing a partial vacuum. The proposed bonding mechanism is polymerization of silanol bonds between wafer pairs. A preferential etch-back process is used to produce Silicon-on-insulator (SOI) whose electrical quality is equal to that of bulk silicon. Capacitor measurements show a 27 µsec minority carrier lifetime and low Q ss at the SOI-"bottom oxide" interface, in addition, there is negligible charge within the bonding oxide. N-channel and p-channel FET devices show threshold voltages and mobilities equal to bulk controls. The subthreshold leakage is less than 1 fA per micron of channel width.

Analysis of Passive Films on Stainless Steel by Cyclic Voltammetry and Auger Spectroscopy

Abstract: Anodic passivation of Type 316L stainless steel in a borate-boric acid buffer solution was studied using cyclic voltammetry and Auger spectroscopy. Based on a comparison with the results obtained on the metals (iron, chromium, and nickel), the reduction peaks appearing in the voltammograms for the steel were attributed to the reductive dissolution of a ferric oxide and to valence transitions associated with chromium and nickel in the oxide. It is shown that cyclic voltammetry in the buffer solution provides a qualitative and semiquantitative analysis of the passive film growth. Okamoto's model of formation of two types of films, determined by the anodization potential, is found to be applicable; the mechanism of oxide growth is related to selective enrichment of iron or chromium, which is based on solubility relationships predicted by thermodynamic considerations. 12 references, 8 figures.