Air atmosphere

Fig. XII-12. Top friction traces for two calcium alkylbenzenesulfonate monolayers on mica where the monolayers are in a liquidlike state. A—in inert air atmosphere B—in saturated decane vapor. Bottom contact radius-load curves showing adhesion energy measured under the same conditions as the friction traces. (From Ref. 53.)...

AIR. (atmospheric) air, a standard for nitrogen and chlorine isotopes APCL atmospheric-pressure chemical ionization, also called plasmaspray API. atmospheric-pressure ionization... 

Air-assisted atomizer Air-atmosphere furnaces Air bag fabric Airbags... 

The most widely used and best known resistance furnaces are iadirect-heat resistance furnaces or electric resistor furnaces. They are categorized by a combination of four factors batch or continuous protective atmosphere or air atmosphere method of heat transfer and operating temperature. The primary method of heat transfer ia an electric furnace is usually a function of the operating temperature range. The three methods of heat transfer are radiation, convection, and conduction. Radiation and convection apply to all of the furnaces described. Conductive heat transfer is limited to special types of furnaces. 

Small loads are commonly processed in a box furnace. The product is placed on the furnace hearth through a door. Box furnaces may be single-ended or double-ended. A single-ended box furnace is usually used in an air atmosphere appHcation where the product can be removed hot from the furnace for cooling. A double-ended box furnace is usually used in a controlled atmosphere appHcation. In this case a water cooler is attached to one end. The product can be placed on the hearth (in the heat chamber) through the front door, then after the product reaches temperature, it is manually transferred into the water cooler for cooling before it is manually removed out the exit door on the other end of the water cooler. 

Air-Atmosphere Furnaces. These furnaces are appHed to processes where the workload can tolerate the oxidation that occurs at elevated temperatures in air. In some special appHcations, the oxidation is not only tolerable but is desired. Some furnaces heat the work solely to promote oxidation. Furnaces designed for air operation are not completely gas-tight which results in somewhat lower constmction costs. There are no particular problems encountered in selecting the insulation systems because almost all refractory insulations are made up of oxides. Heating element materials are readily available for the common temperature ranges used with air atmospheres. 

Phthalates in Air. Atmospheric levels of phthalates in general are very low. They vary, for DEHP, from nondetectable to 132 ng/m (50). The latter value, measured in 1977, is the concentration found in an urban area adsorbed on airborne particulate matter and hence the biological avaUabUity is uncertain. More recent measurements (52) in both industrial and remote areas of Sweden showed DEHP concentrations varying from 0.3 to 77 ng/m with a median value of 2 ng/m. ... 

Other techniques include oxidative, steam atmosphere (33), and molten salt (34) pyrolyses. In a partial-air atmosphere, mbber pyrolysis is an exothermic reaction. The reaction rate and ratio of pyrolytic filler to ok products are controlled by the oxygen flow rate. Pyrolysis in a steam atmosphere gives a cleaner char with a greater surface area than char pyroly2ed in an inert atmosphere however, the physical properties of the cured compounded mbber are inferior. Because of the greater surface area, this pyrolytic filler could be used as activated carbon, but production costs are prohibitive. Molten salt baths produce pyroly2ed char and ok products from tine chips. The product characteristics and quantities depend on the salt used. Recovery of char from the molten salt is difficult. 

Samples were tested on in a melt of salts (75% Na SO, 25% NaCl) at 950°C in an air atmosphere for 24 hours. Micro X-rays spectrum by the analysis found that the chemical composition of carbides of an alloy of the ZMI-3C and test alloys differs noticeably. In the monocarbide of phase composition of an alloy of the ZMI-3C there increased concentration of titanium and tungsten is observed in comparison with test alloys containing chemical composition tantalum. The concentration of more than 2% of tantalum in test alloys has allowed mostly to deduce tungsten from a mono carbide phase (MC) into solid solution. Thus resistance of test alloys LCD has been increased essentially, as carbide phase is mostly sensitive aggressive environments influence. The critical value of total molybdenum and tungsten concentration in MC should not exceed 15%. 

Trace contaminants are also significant at charged solid surfaces, affecting both the charging process and the surface conductivity. In ambient air atmospheres their effect is often determined by interaction with adsorbed water vapor, whose dominant concentration may be sufficiently large to form a monolayer. Topical antistatic agents for solids typically rely on interaction with adsorbed water and can lose effectiveness at low relative humidity (4-2.1). 

Striking of a smear or thin coating of alloy on rusty steel with a hammer. The glancing impact of stainless steel, mild steel, brass, copper-heryllium hronze, aluminium copper and zinc onto aluminium smears on rusty steel can initiate a thermite reaction of sufficient thermal energy to ignite flammahle gas/vapour-air atmosphere or dust clouds. 

Palmer, K. N. and Rogowski, Z. W. 1968. The Use of Flame Arresters for Protection of Enclosed Equipment m Propane-Air Atmospheres. IChemE Symposium Series No. 25, pp. 76-85. Institution of Chemical Engineers, Rughy, England. 

Luft,/. air atmosphere, -ablass, m. escape of air air outlet, -abscheider, m. air separator. deaerator, -abschluss, m. exclusion of air air trap, -abschreckung,/. (Metal.) air quenching, -abwehr, /. air defense, antiaircraft. -abzug. m. air exhaust, air exhaiister. 

Under certain conditions, it will be impossible for the metal and the melt to come to equilibrium and continuous corrosion will occur (case 2) this is often the case when metals are in contact with molten salts in practice. There are two main possibilities first, the redox potential of the melt may be prevented from falling, either because it is in contact with an external oxidising environment (such as an air atmosphere) or because the conditions cause the products of its reduction to be continually removed (e.g. distillation of metallic sodium and condensation on to a colder part of the system) second, the electrode potential of the metal may be prevented from rising (for instance, if the corrosion product of the metal is volatile). In addition, equilibrium may not be possible when there is a temperature gradient in the system or when alloys are involved, but these cases will be considered in detail later. Rates of corrosion under conditions where equilibrium cannot be reached are controlled by diffusion and interphase mass transfer of oxidising species and/or corrosion products geometry of the system will be a determining factor. 

The obvious method of reducing corrosion in fused salts is to choose a system in which either the metal can come to equilibrium with the melt, or else truly protective passivity can be attained. In most cases in industry neither of these alternatives is used. In fact, fused salt baths are usually operated in air atmosphere, and the problem is the prevention of excessive corrosion. This can be done in two ways, (a) by reducing rates of ingress of oxidising species (mainly O2 and H2O) from the atmosphere, and rates of their diffusion in the melts, and (b) by keeping the oxidising power (redox potential) of the melt low by making periodic additions to the bath. 

As additional experiments, investigate the decomposition of calcium oxalate in a static air atmosphere and in a nitrogen atmosphere at a flow rate of 10 mL min -. Compare the final stage of the decomposition, i.e. the conversion of calcium carbonate to calcium oxide, using different furnace atmospheres. 

It is noteworthy that metallic copper or cuprous bromide used under nitrogen atmosphere shows only a very short induction time. This last result points out the inhibitor role of the oxygen of the air atmosphere and most likely the important role taken either by reduced species or by radical intermediates in the catalytic cycle. 

In order to check more exactly these conclusions, various additives were used under normal air atmosphere (Fig. 19). 

The Pd-catalysed Heck reaction performed with thiourea as the Ugand exhibit good activities for some catalysts. As for carbene ligands [104], steric hindrance improves catalytic results. Thus, thioureas wearing bulky substituents afford the formation of air- and moisture-stable Pd complexes [105]. For example, the catalyst obtained with 2mol% Pd(dba)2 and Ar,M -dimesitylene-ethylene thiourea (Scheme 24) was still active even after 2 months in an air atmosphere. 

Thermal treatments can be applied to modify the properties of a material, for example, dealumination and optimization of crystalHne phases. These techniques do not require oxidants. Oxidative thermal treatments are generally employed to activate molecular sieves, by removing the organic templates employed during synthesis. This is one of the key steps when preparing porous catalysts or adsorbents. In air-atmosphere calcination, the templates are typically combusted between 400... 

The residual fraction of Zn after combustion without steam at 1273 K was about 80 %, meanwhile the residual fraction after pyrolysis was about 30 %. Also at 1423 and 1573 K, the residual fraction of Zn after combustion was greater than in the case of pyrolysis. This was considered that under N2 atmosphere, Zn in coal was released as the compound that should be volatized at each temperature, however under air atmosphere, a part of Zn were oxidized into ZnO (mp 2521 K) which was very stable at high temperature. When the combustion was carried out with additional steam, the residual fraction of Zn was same as the cases in the absence of steam. However, the residual fraction of Zn after steam gasification was about 60 %, greater than the residual fraction after pyrolysis (about 30 %) and smaller than the residual fraction after combustion (about 80 %). This was considered that under steam gasification, a part of Zn, which should be emitted at 1273 K, was oxidized into ZnO by additional steam. 

We prepared ceria on Ni substrate by sol-gel coating method. Ceria sol solution was prepared with ceria sol solution (Alfa, 20% in H2O, colloidal dispersion) mixed with ethanol (99.9%, Hayman) with weight ratio (1 2) and stirred. Ceria was deposited on Ni substrate by dip coating method. The variation number of dipping was carried out to obtain different coating ratio. The anode was completely dipped into the ceria sol solution for several seconds and dried at a temperature of 50 C for 24 hours in air atmosphere followed by calcination at 700 C for 30 minutes in 5%H2-N2 atmosphere. 

A more practical, atom-economic and environmentally benign aziridination protocol is the use of chloramine-T or bromamine-T as nitrene source, which leads to NaCl or NaBr as the sole reaction by-product. In 2001, Gross reported an iron corrole catalyzed aziridination of styrenes with chloramine-T [83]. With iron corrole as catalyst, the aziridination can be performed rmder air atmosphere conditions, affording aziridines in moderate product yields (48-60%). In 2004, Zhang described an aziridination with bromamine-T as nitrene source and [Fe(TTP)Cl] as catalyst [84]. This catalytic system is effective for a variety of alkenes, including aromatic, aliphatic, cyclic, and acyclic alkenes, as well as cx,p-unsaturated esters (Scheme 28). Moderate to low stereoselectivities for 1,2-disubstituted alkenes were observed indicating the involvement of radical intermediate. 

Those heating elements given in Table 6-1 are generally used in air atmosphere, up to about 1800 °C. If one needs to produce a melt above 1800 °C, it is necessary to use refractory metals which must be used in an inert atmosphere. Table 6-2 lists some of these heating elements ... 

In a moist air atmosphere, vinyl acetate polymerised spontaneously with extreme violence. The investigation led to the following interpretation. In the presence of moisture, the acetate hydrolysed forming acetaldehyde ... 

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