Diffusion carbonates

The ammonium polysulfide, (NH4)2SX (with x=2 to 6) is produced in an electrochemical cell where aqueous ammonium sulfide, (NH4)2S, solution is supplied as electrolyte. The cell comprises an anode and a gas diffusion carbon cathode over which gaseous 02 is supplied in contact with the electrolyte.11 The cell operated continuously at pressures up to 60 bar. The applied potential, UWc> was 0.01 to 5 V. Pronounced electrochemical promotion behaviour was observed at Uwc values as low as 0.02 V with a current 1=0.5 A. 

Liquid Lwhttmmg creates a diffused carbon (possibly nitrogen) case. Base metals art low-carbon steels and low-carbon alloy Meets. Process temperature range is 815-980 C 11500-1800 F). 

Via until carburizing creates a diffused carbon case. Base metals are... 

Gas carbonitriding creates a diffused carbon and nitrogen case. Base niciuls are low carbon steels, low-carbon alloy steels, and stainless steels. Proofs temperature range is 7W)-870JC 11400-1600 K). 

Liquid (cyatuding) creates a diffused carbon and nitrogen case. Base metals are low-carbon sieels. Process temperature range is 760-870 JC (141)0-1600 F). 

Creates a diffused carbon, titanium, and TIC case. Base ineials are alloy and tool steels Process temperature range is 900-1010 C (1650- 1X50"F). 

There have been more detailed studies on the Stfl reaction very recently. In 1975, Baybutt248 found that for CH4 + H- the addition of polarization functions to the basis has very little effect on the barrier for the reaction, but diffuse carbon s-functions have a more pronounced effect, increasing the barrier by 42—68 kJ mol-1... 

Carbon-13 rotating-frame relaxation rate measurements are used to elucidate the mechanism of gas transport in glassy polymers. The nmr relaxation measurements show that antiplasticization-plasticization of a glassy polymer by a low molecular weight additive effects the cooperative main-chain motions of the polymer. The correlation of the diffusion coefficients of gases with the main-chain motions in the polymer-additive blends shows that the diffusion of gases in polymers is controlled by the cooperative motions, thus providing experimental verification of the molecular theory of diffusion. Carbon-13 nmr relaxation... 

Due to its low solubility in magma, CO2 is able to exsolve from magma even at high pressures. Diffuse carbon dioxide emissions can... 

Activated carbons should be selected on the basis of different model substances and then tested in dynamic conditions. Analysis of adsorption isotherms and curves of filter breakthrough gives a lot of information about adsorption and kind of diffusion. Carbon selected for water treatment should be tested in real conditions of semi—technical scale. 

A similar problem exists for the addition of steel scrap. Scrap melting not only depends on temperature but also on carbon concentration. Diffusive carbon transport to the scrap/metal bath interface is therefore an important factor for melting behaviour. A function that treats the melting as well as the heating up of the scrap prior to melting was implemented. 

Diffusion Carbon monoxide diffusing capacity Measurement of efficiency of alveolar gas exchange decreases with thickening of alveolar blood-air barrier... 

DIFFUSE CARBON AND INORGANIC CARBON SEDIMENTS, sjoooom... 

The carbon monitors applied for the determination of carbon activities in lithium or sodium apply diffusion cells. Carbon dissolved in alkali metals contacting the probes diffuses through the probe wall, a thin tube wall of pure iron. The diffusing carbon in consumed by chemical reactions in the probe ... 

Problem 4.8. The aim of carburization is to increase the carbon concentration in the surface layers of steel in order to achieve a harder wear-resistant surface. This is usually done by holding the steel in a gas mixture containing CH4 and/or CO at a temperature where austenite is present. A thick plate of 0.3 wt % C steel is carburized at 930 °C. The carburizing gas used in the treatment holds the surface concentration at 1.0 wt % C. Assume the plate is so thick that the diffusing carbon does not reach the opposite side of the plate over the course of the treatment. Given that the diffusivity of carbon in iron at this temperature is > = 1.1 x 10 m /s, determine how long it will take for the carbon concentration to reach 0.6 wt % C at a depth of 0.3 mm ... 

For instance, carbon fibers have been used widely for orthopedic applications. Matrices of carbon fibers were implanted in patients for the treatment of chronic painful articular defects of the patella [47], with mixed results at 33 months mean follow-up with low patient satisfaction. Synovial biopsies have pointed out consistent seeding of the joint with diffuse carbon fiber debris and histiocytic giant-ceU reaction in the synovium, sometime associated with low-grade inflammatory response. These results discouraged further procedures for lesions of the articular cartilage of the patella with carbon fiber matrix. 

The addition of an iron catalyst to the treated solution allows the formation of OH via Fenton s reaction (1). In 1986, M. Sudoh et al. were the first to apply the method to wastewater treatment. Since then, graphite, carbon-PTFE O2 diffusion, carbon felt, activated carbon fiber (ACF), reticulated vitreous carbon (RVC), carbon sponge, and carbon nanotubes (CNTs) have been used as cathode materials [1]. 

Gas Diffused carbon 815-980 (1500-1800) 75 un-1.5 mm (3-60 mils) 50-63(a) Low-carbon steels, low-carbon alloy steels Good control of case depth, suitable for continuous operation, good gas controls required, can be dangerous... 

Gas Diffused carbon and nitrogen 760-870 (1400-1600) 75 im-0.75 nun (3-30 mils) 50-65(a) Low-carixm steels, low-caibtm alloy steels, stainless steels Lower temperanire than caibuii g (less disRution), sli dy harder case than carburizing, ccmtrol critical... 

Ferritic Diffused carbon 480-590 nitrocarbmi- and nitrogen (900-1090) zing (a) Requires quench from austenitizing temperature. Source Ref 7 2.5-25 tun (0.1-1 mil) 40-60(a) Low-carbtm steels ... 

It is clear Ifom Fig. 7 that the silicon self-diffusion coefficient in undoped crystals is lower than in doped crystals. An opposite dependence was observed for the carbon self-diffusion coefficient. According to the law of acting masses, the silicon vacancy (acceptor) concentration increases with increasing donor dopant concentration (nitrogen). AU this leads to an increase in the diffusion coefficient in the presence of a vacancy mechanism of self-diffusion. Carbon vacancies are donors, and their concentration decreases when the donor concentration is increased. This leads to a decrease in the carbon self-diffusion coefficient. 

Carburizing (substrate) The process of diffusing carbon into a surface region of an alloy containing Cr, Ni, or Mo to form a carbide phase and give dispersion strengthening. 

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