Process heat-treatment

All subsequent green coke operations were made in a second coker, which was fashioned from steel pipe approximately 18 cm in diameter and 25 cm in length. A metal plate was welded to one end and a metal collar was welded to the other end such that a steel lid could be bolted to the system. Typically, about 250 to 500 g of pitch were sealed imder nitrogen in the coker reactor and the system placed in a large temperature-programmable furnace. The heat treatment process was as follows. The temperature was raised 5°C/min to 350 °C and then l°C/min to 425°C and the temperature held at 425°C for 90 minutes. Finally the temperature was raised further at 3°C/min to between 500 and 600°C, and held there for 3 hours. The coker was cooled to room temperature and the material recovered to determine green coke yield. 

The sulfate process is based on the attack of activated beryl by sulfuric acid to form water-soluble Be and A1 sulfates and insoluble silica. A flow diagram summarizing this process is given in Scheme 1. Activated beryl must be used since the natural ore is resistant to acid attack except by HF, which is prohibitively expensive. High-grade beryl ore (> 10% BeO) is normally activated by a heat-treatment process... 

Heat treatment of aluminum products frequently involves the use of a water quench in order to achieve the desired metallic properties. Of the 266 aluminum forming plants, 84 use heat treatment processes that involve water quenching. The sampling data for classical and toxic pollutants from... 

General Aspects and Heat Treatment Effects. After him formation, for most of the hlms aimed at electronic applications (other than amorphous oxides, such as Si02), the hlms are subjected to a heat treatment process for removal of residual organic species (entrapped solvent as well as the organic constituents associated with the precursor species), densihcation (elimination of residual porosity and structural free volume in the him), and crystallization. 

There appears to be rather limited reporting of results from field trials of thermally modified wood. Welzbacher and Rapp (2004) have given preliminary data on an ongoing field trial of a number of heat-treatment processes with softwood and hardwoods up to 2.5 years duration. All workers in this area are of the opinion that heat-treated wood is suitable only for out-of-ground applications (Hazard Classes 1, 2 and 3). 

ThermoWood is produced by a heat-treatment process in the presence of steam, and is thus a hygrothermal treatment. The steam acts as a blanket to limit the oxidative degradation of wood, and there are also additional reactions occurring as a result of the presence... 

As mentioned previously (see p. 237), the 1,2,3-benzotriazinones function as masked diazonium compounds, and the so-called Pologenowe dyes developed in Poland are operated on this principle and have been in use there since 1959. There are three major advantages associated with the use of 1,2,3-benzotriazinones as azo-dye equivalents (1) The equilibrium that theoretically exists between the heterocyclic system and the diazonium compound normally lies completely to the side of the cyclic compound. Opening of the heterocyclic ring can be easily accomplished thermally, and hence dye formation can be induced by heat treatment processes. (2) Many 1,2,3-benzotriazinones are reasonably water soluble and the sodium salts even more so consequently, complete permeation of fabric fibres by the dye precursors immediately prior to generation of the dye can be ensured. (3) The colors produced are fast, and some of them can be made highly water insoluble. ... 

Sol-gel process is the generic term for wet chemistry methods that start from mixture of molecular precursors and through condensation, deposition and heat treatment processes lead to a final multicomponent system (7-9). Some of the advantages are well known such as ... 

Emission of nanoparticles in the atmosphere from anthropogenic sonrces (machines, aero engines, power stations, smelters, plasma, welding and heat treatment processes) has been continnonsly inaeasing ever since the beginning of the indnstrial revolntion. 

Annealing A heat treatment process directed at improving performance by removing stresses in the material formed during its fabrication. Typically, the part, sheet, or film is brought to a specific temperature for a definite period of time, and then cooled down slowly to ambient temperature. 

The majority of carbon fibers are made from petroleum pitch or polyacrylonitrile (PAN), with a heat treatment process similar to glassy carbon s [47]. The... 

A1 and O. Upon heat treatment in hydrogen atmosphere the surface flatness is much improved the RMS roughness is 0.2 - 0.3 ML (0.04 - 0.06 nm) [26,28], This heat treatment process is commonly used before growth of low temperature buffer (or nucleation) layers of AIN or GaN as shown in FIGURE 4 [24], Sapphire surfaces also become flat at a similar level by heat treatment in air [27],... 

Characterization Techniques for Pitch Materials. Among a number of characterization techniques developed in Japan, the technique due to the members of the Society of Heavy Oil, led by Kunugi, stands out as particularly useful. The analytical data are treated by computer methods to construct average molecular structures for the carbonaceous materials. Sanada s group in Hokkaido University used high-temperature NMR and ESR data obtained by in situ measurements of pitch materials in molten salt (21). Much information on mesophase behavior during the heat-treatment process was obtained in this way. 

Depending on the nature of the product, pretreatment of the feed material may be desirable to improve the separation characteristics. Possible techniques are based on chemical or physical treatment and include thickening, flocculation, and coagulation. A simple heat treatment process where the temperature of the broth is elevated and held for a period of time can reduce... 

Conversion of the as-deposited film into the crystalline state has been carried out by a variety of methods. The most typical approach is a two-step heat treatment process involving separate low-temperature pyrolysis ( 300 to 350°C) and high-temperature ( 550 to 750°C) crystallization anneals. The times and temperatures utilized depend upon precursor chemistry, film composition, and layer thickness. At the laboratory scale, the pyrolysis step is most often carried out by simply placing the film on a hot plate that has been preset to the desired temperature. Nearly always, pyrolysis conditions are chosen based on the thermal decomposition behavior of powders derived from the same solution chemistry. Thermal gravimetric analysis (TGA) is normally employed for these studies, and while this approach seems less than ideal, it has proved reasonably effective. A few investigators have studied organic pyrolysis in thin films by Fourier transform infrared spectroscopy (FTIR) using reflectance techniques. - This approach allows for an in situ determination of film pyrolysis behavior. 

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