Showing papers on "Inert gas published in 1989"

Collision induced dissociative chemisorption of CH4 on Ni(111) by inert gas atoms: The mechanism for chemistry with a hammer

Abstract: The dissociation of CH4 physisorbed on Ni(111) at 46 K is observed to be induced by the impact of incident inert gas atoms. The dynamics and mechanism of this new process, collision induced dissociative chemisorption, are studied by molecular beam techniques coupled with ultrahigh vacuum electron spectroscopies. The absolute cross section for collision induced dissociation is measured over a wide range of kinetic energies (28–109 kcal/mol) and incident angles of Ne, Ar, and Kr atom beams. The cross section displays a complex dependence on the energy of the impinging inert gas atom characteristic of neither total nor normal energy scaling. Quantitative reproduction of the complex dependence of the cross section on the Ar and Ne incident energy by a two‐step, dynamical model establishes the mechanism for collision induced dissociation. Collision induced dissociation occurs by the impulsive transfer of kinetic energy upon collision of Ar or Ne with CH4, followed by the translationally activated dissociative ...

Variable‐heating‐rate wire‐mesh pyrolysis apparatus

Abstract: An electrically heated wire‐mesh apparatus for pyrolysis studies has been developed which uses computer‐driven feedback control for the heating system and thus can apply virtually any time‐temperature history to the sample. Internal components are water cooled to prevent heat buildup during long runs. Using this system, coal pyrolysis has been studied at heating rates from 0.1 to about 5000 K/s and temperatures up to 1000 °C. Alternating current is used for heating; this allows the thermocouples to be attached directly to the sample holder and also makes power regulation relatively simple. For atmospheric‐pressure experiments, a gas sweep can be forced through the sample holder to remove products from the heated zone and also to concentrate them in a trap which can be removed from the apparatus and weighed to establish tar yields directly. Although the design is optimized for atmospheric‐pressure operation, relatively simple modifications allow operation under vacuum or at pressures of up to 160 bars in inert gas or hydrogen. The apparatus has been used to investigate a number of phenomena in coal pyrolysis and, most significantly, has demonstrated the existence of a heating‐rate effect which is independent of reactor geometry.

Sintering metal powders into structures without sintering aids

Abstract: Sintering metal powder in inert and/or reducing atmosphere has been found to result in a hard porous metal structure without the use of sintering aids. The oxidation resistance of the structure can be enhanced by the firing process comprised of the following steps: oxidation, reduction, and then inert gas sintering.

Method of forming a barrier layer between a silicon substrate and an aluminum electrode of a semiconductor device

Abstract: A titanium nitride barrier layer of 50 to 200 nm in thickness is fabricated between a silicon substrate and an aluminum electrode layer of an IC device by reactive sputtering performed in a mixed gas including oxygen in a proportion of 1 to 5% by volume relative to other gases, comprising an inert gas and a reactive gas, providing the temperature of the silicon substrate at 350° to 550° C. during the reactive sputtering, so that the product has a failure rate, indicating the property of preventing mutual diffusion of silicon and aluminum atoms from occurring, of less than 1% and a resistivity less than 100 μΩ.cm.

Oxidation of Chemically‐Vapor‐Deposited Silicon Nitride and Slnglem‐Crystal Silicon

Abstract: The present 1000 C and 1300 C oxidation tests on 111-oriented single-crystal Si and dense CVD Si3N4 notes the oxidation rates of the latter in wet O2, dry O2, wet inert gas, and steam atmosphere conditions to be several orders of magnitude lower than the rates for the former in identical atmospheric conditions. Although the parabolic rate constant for Si increased linearly as the water vapor pressure increased, the parabolic rate constant for Si3N4 exhibited a nonlinear dependency on water vapor pressure in the presence of O2. NO and NH3 formation at the reaction interface of Si3N4, and the counterpermeation of these reaction products, are noted to dominate reaction kinetics.

Reactions of Kr+, Kr2+, Xe+ and Xe2+ ions with several molecular gases at 300 K

Abstract: The reactions of the atomic ions Kr+ and Xe+ and the molecular ions Kr2+ and Xe2+ have been studied with several molecular gases at 300 K using a selected ion flow tube (SIFT). In some of the atomic ion reactions differential reactivity was observed between the spin-orbit states (2P3/2, 2P1/2) of the ions and, when this was so, the lower energy 2P 3/2 state of both ions was observed to react more rapidly than the 2P1/2 state, in accordance with the findings of previous work. Whereas charge transfer was the only reaction mechanism observed for the atomic ions, both charge transfer and inert gas/reactant molecule switching were observed in several reactions of the molecular ions, the latter process producing ions such as KrCH4+ and XeC2H2+. By considering the kinetics of the near-thermoneutral charge transfer reactions of Kr2+ with N2O and Xe2+ with COS, the dissociation energies of the molecular ions have been determined to be

Pressure Effects on the Thermal Stability of Silicon Carbide Fibers

Abstract: Commercially available polymer derived SiC fibers were treated at temperatures from 1000 to 2200 C in vacuum and argon gas pressure of 1 and 1360 atm. Effects of gas pressure on the thermal stability of the fibers were determined through property comparison between the pressure treated fibers and vacuum treated fibers. Investigation of the thermal stability included studies of the fiber microstructure, weight loss, grain growth, and tensile strength. The 1360 atm argon gas treatment was found to shift the onset of fiber weight loss from 1200 to above 1500 C. Grain growth and tensile strength degradation were correlated with weight loss and were thus also inhibited by high pressure treatments. Additional heat treatment in 1 atm argon of the fibers initially treated at 1360 atm argon caused further weight loss and tensile strength degradation, thus indicating that high pressure inert gas conditions would be effective only in delaying fiber strength degradation. However, if the high gas pressure could be maintained throughout composite fabrication, then the composites could be processed at higher temperatures.

Direct fluorination process for making perfluorinated organic substances

Abstract: A liquid phase process for making perfluorinated organic substances which comprises directly contacting in a temperature-controlled reactor a diluted solution or dispersion of a perfluorinateable, organic substance in a liquid, inert medium with a stoichiometric excess of fluorine gas, optionally diluted with an inert gas, to perfluorinate said organic substance at a temperature and a flow rate of inert gas (if used) sufficient to volatilize the resulting by-product hydrogen fluoride, removing said hydrogen fluoride from the reactor as it is produced, and separately removing from the reactor the resultant solution or dispersion of perfluorinated organic substance.

Module for determining diffusing capacity of the lungs for carbon monoxide and method

Abstract: An apparatus for introducing test gas commonly containing an inert gas and carbon monoxide to a patient through a mouthpiece which, in turn, is attached to a sample chamber within which are arranged sensors enabling measuring of carbon monoxide, carbon dioxide, an inert gas or other gases. Valving permits the test gas to be inhaled by the patient and then exhaled into the chamber. Further valving at the outlet of the chamber permits evacuation through a gas volume measuring device after measurements within the chamber have been completed. Sample chambers may be of various shapes but preferred forms are essentially linear or closed loop arrangements.

Selection and preparation of activated carbon for fuel gas storage

Abstract: Increasing the surface acidity of active carbons can lead to an increase in capacity for hydrogen adsorption. Increasing the surface basicity can facilitate methane adsorption. The treatment of carbons is most effective when the carbon source material is selected to have a low ash content i.e., below about 3%, and where the ash consists predominantly of alkali metals alkali earth, with only minimal amounts of transition metals and silicon. The carbon is washed in water or acid and then oxidized, e.g. in a stream of oxygen and an inert gas at an elevated temperature.

Casting particulate and fibrous metal-matrix composites by vacuum infiltration of a liquid metal under an inert gas pressure

Abstract: A new method of making metal-matrix composites is reported. This method combines the essentials of three liquid-phase fabrication methods: (i) vacuum infiltration, (ii) infiltration under an inert gas pressure, and (iii) squeeze casting. In this method, the particulate or fibrous preform is placed in a mould and the matrix alloy is placed above the preform. The matrix alloy is heated to the liquidus temperature together with the mould and the preform under vacuum. Then an inert gas like argon is compressed on to the top surface of the matrix-alloy melt, forcing the melt to infiltrate the preform. The pressure is 1000 to 2500 psi. As the melt is just at liquidus temperature, it is much lower than that used in squeeze casting. Moreover, the pressure is an order of magnitude lower than that used in squeeze casting. The low temperature lessens the interfacial reaction between the matrix and the filler, while the low pressure essentially eliminates preform compression. This method has been successfully used to fabricate aluminium-matrix composites reinforced by short ceramic fibres, continuous ceramic fibres, SiC particles, Al2O3 particles, graphite flakes and SiC whiskers.

Apparatus and process for arc vapor depositing a coating in an evacuated chamber

Abstract: A process and apparatus for coating a substrate with source material from a solid cathode in a vacuum chamber supplied with a reactive or inert gas at low pressure. An electric arc is generated between an evaporable end surface of the cathode and an anode. An elongated member surrounds the cathode and extends a predetermined minimum distance "X" beyond the evaporable end surface of the cathode to form a cathode chamber. The inert or reactive gas is directed to flow into the cathode chamber before entering the vacuum chamber.

Method for high temperature thermal processing with reduced convective heat loss

Abstract: A method for inducing a reaction in a reaction chamber of a reactive carrier having a first specific heat, on a reaction surface of a substrate. The method comprises the steps of supporting the substrate in the reaction chamber. Next, the substrate is heated to a reaction temperature, so that the reaction surface has an essentially balanced temperature distribution. The reactive carrier is mixed with an inert gas having a second specific heat to form a reaction mixture, wherein the second specific heat is lower than the first specific heat. Finally, the reaction mixture is supplied into the chamber so that it flows over the surface of the substrate. Because the inert gas has a lower specific heat than the carrier, the overall specific heat of the reaction mixture is reduced. With a lower specific heat, less heat is transferred from the wafer into the reaction mixture. This reduces convective heat loss and thermal gradients in the substrate. The technique is particularly applicable to rapid thermal processing of semiconductor wafers for epitaxial growth of silicon. According to this aspect, hydrogen is the reactive carrier, mixed with a chlorinated silicon source. The inert gas may be argon.

Ultimate pressure of the order of 10-13 Torr in an aluminum alloy vacuum chamber

Abstract: An extremely high vacuum chamber for the calibration of ultrahigh vacuum gauges was fabricated and tested. The chamber has an inner diameter of 250 mm and is 1800 mm long. It has 20 gauge ports and a liquid‐nitrogen shroud inside to suppress interference between gauges and to avoid pressure rise due to thermal radiation from the gauges. The vacuum chamber was made of specially extruded aluminum alloy A6063‐T6‐EX in an oxygen and argon atmosphere. The chamber was assembled using tungsten inert gas welding in an argon atmosphere. After a bakeout at 150 °C for 24 h, a specific outgassing rate of the order of 10−13 Torr l/s cm2 was obtained. The system was evacuated with a turbobacked 300 l/s turbomolecular pump. The extremely high vacuum is maintained by two 300 l/s sputter ion pumps and a titanium sublimation pump with a liquid‐nitrogen shroud. These pumps are also made of aluminum alloys. An ultimate pressure of 3×10−13 Torr was measured with a point collector gauge with spherical anode. Residual gas analy...

Experimental study of coal pyrolysis and hydropyrolysis at elevated pressures using a variable heating rate wire-mesh apparatus

Abstract: A high-pressure wire-mesh reactor has been developed with a heating rate range from 1 to 1000 K/s, and the capability of applying extended isothermal holding times (up to 200 s at 600 o C has been used). These improvements to the range of conditions that can be covered with this type of instrument have been achieved by the use of computerized feedback temperature control and the provision of water cooling for the internal electrode assembly. Experiments using samples of Linby and Pittsburgh No. 8 coals have shown that, as inert gas pressure is raised, the effect of increased heating rates, almost completely disappears. In high-pressure hydrogen slow heating (5 K/s) can even give higher total volatile yields than rapid (1000 K/s) heating with short holding times, though this was found possibly to be due to the greater time available for char hydrogasification during heating

Process for extruding thermoplastic materials using low pressure inert gases as foaming agents

Abstract: A process for producing microcellular foamed articles wherein a low pressure compressible, inert gas such as nitrogen is used as a foaming agent. The process comprises introducing a thermoplastic material into an inlet of an extruder having a length to diameter ratio of at least 30:1, said extruder comprising a screw having at least one stage; heating the thermoplastic material in a melt zone to a temperature sufficient to melt or soften the thermoplastic material to form a melted thermoplastic material; injecting an insoluble compressible, inert gas into the melted thermoplastic material at a position approximately 1 to 2 screw diameters downstream of the melt zone; mixing the molten thermoplastic material and the inert, compressible gas to form a homogeneous dispersion of insoluble bubbles within the material; reducing the pressure of the molten thermoplastic material causing the homogeneously dispersed bubbles to expand within the melted thermoplastic material to form a foamed article and cooling the foamed article to a temperature below the melting or softening point of the foamed article.

Arrangement for producing a gas flow which is enriched with the vapor of a low-volatile substance

Abstract: An arrangement for producing a gas flow which is enriched with the vapor of a low-volatile material. The arrangement comprises a vessel (1) having an interior space (12) for holding a powder bed (13), which consists of a low-volatile material and an additional solid inert component. The vessel is arranged in a thermostatically controlled bath (2). A gas flow (4, 16) consisting of an inert gas flows through the arrangement, preferably in the direction of the gravitational force. The gas flow passes, in this sequence, through a thick gas inlet plate (10), the powder bed (13) and a thin gas outlet plate (14). By proper dimensioning the component parts of the arrangement and providing a low pressure in the arrangement a high mass flow of the low-volatile material with a flow constant of a long duration is achieved. The enriched gas flow is conducted, for example, to a low-pressure CVD reactor.

Method for removing mercury from hydrocarbon oil by high temperature reactive adsorption

Abstract: A method is provided for removing mercury from hydrocarbon fluids by high temperature reactive adsorption. A hydrocarbon feed passed through an adsorbent mass including a reactive adsorbent such as silver or copper sulfide on an alumina support. The optimum temperature of the feed to be treated depends upon the 90% boiling points corresponding to heavier feeds. A hydrocarbon condensate feed may be drawn from a stabilizer column in a natural gas processing plant at a temperature in excess of 204°C (400° F). If a metallic silver/alumina adsorbent is employed, the adsorbent may be regenerated through high temperature oxidation. Once oxidation is complete, the temperature is lowered in a reducing or inert atmosphere.

The burning velocities of methane and SNG mixtures with air

Abstract: The burning velocities of methane and Synthetic Natural Gas (SNG) mixtures with air were measured in a stationary flat flame on a burner at a pressure of 1 bar and a temperature of 25{sup o}C, by means of a particle-tracking method. Measurements were made from methane-air flame over the equivalence range 0.8 - 1.2 for comparison with data obtained by other researchers using similar low-stretch burner flames. The maximum burning velocity of methane was found to be 42 cm/s. The SNG mixtures studied were methane/hydrogen and methane/hydrogen/propane, with hydrogen contents up to 40 mol% and propane contents up to 19 mol%. The influence of inert gases, nitrogen and CO{sub 2}, on the burning velocity of methane/air mixture was also determined. (author).

Vapor growth apparatus

Abstract: PURPOSE:To hold a growth rate constant and to obtain a uniform distribution of a film thickness by providing a window transparent for an ultraviolet light in an enclosure, and separately attaching an inert gas diffusing and material gas discharging vacuum evacuation systems at the lower section of the window in the enclosure. CONSTITUTION:Material gas is supplied from a material gas supply tube 6 in a reduced pressure state to a plurality of semiconductor wafers 5 placed in a disc-shaped susceptor 3 in an openable stainless steel bell-jar 1 and a quartz bell-jar 2 and uniformly heated by a secured resistance heater 4 while being rotated in a predetermined direction at a constant speed by a motor 17. Inert gas is so fed under the control of vacuum evacuation systems 9, 9' as not to diffuse from a diffusing tube 8 to the tops to eliminate the contact with an irradiation window 10, reaction gas on the wafers 5 is photochemically reacted by irradiating them with a light having a specific wavelength through the window 10 from a UV light source lamp 11, and desired thin films are vapor grown on the wafers 5 with good uniformity of film thickness distribution. Thus, the uniformity of the film thickness distribution and the growth rates of the wafers are held constant for a long period of time, thereby improving the throughput.

Diamond and its preparation by chemical vapor deposition method

Abstract: A diamond having improved properties is produced by a method which comprises introducing a mixture of hydrogen (A), an inert gas (B) and a carbon-containing compound (C) in molar ratios which satisfy the following equations: ##EQU1## generating a low temperature plasma with one of direct current and an alternating current electromagnetic field under pressure of 5 to 760 Torr to form the diamond on a substrate, wherein there is no substantial differnce between a place where the plasma is generated and a place where the diamond is formed on the substrate.

Fuel cell power generating system

Abstract: PURPOSE:To make it possible to control a maximum temperature, a minimum temperature, and a mean temperature in a cell by installing a control means which controls the temperature of a fuel cell stack in a specified value. CONSTITUTION:A maximum temperature, a minimum temperature, and a mean temperature in a cell are calculated with a computing element 15 based on the voltage and current of a fuel cell stack 1, data obtained in an oxidizing gas flow detector 11, an oxidizing gas inlet temperature detector 12, and a cell atmosphere temperature detector 13, and gas composition, and compared with each target figure. If calculated values are out of target figures, each setable range of an oxidizing gas inlet temperature and a temperature within a pressure container 7, which meets a target maximum temperature, a target minimum temperature, and a target mean temperature in an oxidizing gas flow rate, is found, and oxidizing gas temperature controllers 10a, 10b, and an inert gas temperature controller 14 are controlled so that the oxidizing gas inlet temperature and the temperature within the pressure container 7 each is in a middle point of its setable range. A maximum temperature, a minimum temperature, and a mean temperature are controlled in each set temperature during operation.

Chemical vapor deposition coatings in fluidized bed reactors

Abstract: Summary A coating technique based on chemical vapor deposition (CVD) in a fluidized bed reactor (FBR) is described. To coat an article, we load the coating material as a powder in an FBR and fluidize it using an inert gas. The system is heated to operating temperature, and vapors of HBr are mixed with the fluidizing gas. The sample to be coated is suspended on top of the bed or immersed into the bed. The reaction of the HBr with the powder in the bed produces halide species of the coating material that can deposit a coating on the substrate by a disproportionation or reduction reaction. Using this technique, we deposited titanium, silicon, zinc, TiN and Si 3 N 4 coatings on substrates such as copper, steel, silica and graphite.

Process for preparing alkyl-substituted aromatic hydrocarbons

Abstract: An alkyl-substituted hydrocarbon is prepared by alkylating an alkyl aromatic hydrocarbon having at least one hydrogen atom at an alpha-position in a side chain with an olefin in the presence of a solid base which is obtainable by heating an alumina, an alkali metal hydroxide and an alkali metal hydride or an alumina containing at least 1.3% by weight of water and an alkali metal hydride in an inert gas atmosphere at a temperature of 200° to 800° C. as a catalyst.

Apparatus for introducing samples into an inductively coupled, plasma source mass spectrometer

Abstract: A sample introducing apparatus for an inductively coupled plasma mass spectrometer comprises a means supplying the inert gas for carrying the vaporized sample, a heater for defining the path through which the inert gas is passed as well as having the inner surface, on which the sample to be analyzed thereon is put and for generating the heat with the electrical being applied, in which the film structure is formed on said surface, and the surface contacted with the inert gas of the film structure vaporized the sample made of any one of the high melting metal oxide and the high melting metal nitride, an electrode structure for supporting the heater and supplying the electrical power to the heater.

Method of manufacturing heat-exchanger

Abstract: A method of manufacturing heat-exchanger excellent in the pitting corrosion resistance is disclosed, wherein, in the manufacture of aluminum heat-exchanger to be brazed under heat in the furnace of inert gas atmosphere using fluoride flux, Zn is disposed at a position of 430° to 620° C. in the furnace to melt and vaporize it and the vapor of Zn is allowed to contact with the fin material and the tube material coated with said flux simultaneously with the brazing under heat of these aluminum components, or the fin material coated with said flux and dried and the tube material without flux are assembled and retained for not less than 1 minute in the vapor of Zn of a temperature lower than the melting point of said flux and higher than the temperature, at which these components are heated, in the inert gas and thereafter brazing is performed at a temperature higher than the melting point of said flux.

Apparatus for forming thin film

Abstract: An apparatus for forming thin film includes a vacuum container to which an active gas, an inert gas, or a mixture thereof is introduced, a source of evaporation for evaporating a substance being evaporated in the vacuum container, a counter electrode disposed in the vacuum container and holding a substrate for forming a thin film thereon in such a manner as to be opposed to the source of evaporation, a grid disposed between the source of evaporation and the counter electrode and having openings which allow the substance being evaporated to pass therethrough, a filament for thermionic emission disposed between the grid and the source of evaporation and a power source device for establishing a predetermined electric potential relationship between the grid, the counter electrode, and the filament.

Sorption apparatus for sorbing active gas

Abstract: In a sorption apparatus for sorbing active gas having a sorption rotor (1) for sorbing active gas, sector-like components (S), pipes and fans (6, 7, 9), the sorption rotor has a cylindrical honeycomb structure, one or more than one sorbent for active gas being exposed on the surface of a multiplicity of small channels in the honeycomb structure and the sector-like components divide the sorption rotor into two or more than two sorption zones (2, 3), a precooling zone (4) and one or more than one reactivation zone (5), an inert gas, such as process air or air to be treated (TA) being sequentially introduced into two sorption zones in order to remove one or more than one active gas such as water vapour which is contained in the inert gas and, for example, dehumidified air (SA) at about -80@C being able to be delivered using a dehumidifying rotor.