Carbon content Subject

Martensitic Stainless Steels. The martensitic stainless steels have somewhat higher carbon contents than the ferritic grades for the equivalent chromium level and are therefore subject to the austenite—martensite transformation on heating and quenching. These steels can be hardened significantly. The higher carbon martensitic types, eg, 420 and 440, are typical cutiery compositions, whereas the lower carbon grades are used for special tools, dies, and machine parts and equipment subject to combined abrasion and mild corrosion. 

The evaluation of heat treatments or the effectiveness of stabilisation by limiting carbon content of these stainless steels can be determined by subjecting specimens to the ASTM standardised acid copper sulphate test or boiling nitric acid test (ASTM A262 1986 see also Sections 9.5 and 1.3). 

From the beginning of 14C studies, bone was burdened with a marginal status as a sample type. It was missing from the list of sample materials which Libby initially recommended [10]. He and other researchers discouraged its use for the reason that the carbon content and specifically the organic carbon content, was low even in relatively recent bone and because it was a very porous structure potentially subject to chemical alteration and presumably to contamination. It was concluded that bone would systematically violate the third assumption of the 14C method as listed in Table 1. (It should be noted that "burned bone" was highly recommended. However, the sample material was the carbonized hair, skin, and other tissue rather than the bone matrix itself.)... 

Carbon content and hydrogen content can be determined simultaneously by the method designated for coal and coke (ASTM D3178) or by the method designated for municipal solid waste (ASTM E777). However, as with any analytical method, the method chosen for the analysis may be subject to the peculiarities or character of the feedstock under investigation and should be assessed in terms of accuracy and reproducibility. There methods that are designated for elemental analysis are ... 

Surface Carbon Analysis. This method is based on the observation that the presence of carbon on automotive body sheet steel, for instance, can be linked to poor corrosion performance. The carbon content on the surface can be determined by subjecting the body sheet to about 500°C in an oxygen environment and determining the CO2 thus formed. 

Drug/Food interactions Theophylline elimination is increased (half-life shortened) by a low carbohydrate, high protein diet, and charcoal broiled beef (due to a high polycyclic carbon content). Conversely, elimination is decreased (prolonged half-life) by a high carbohydrate low protein diet. Food may alter the bioavailability and absorption pattern of certain sustained-release preparations. Some sustained-release preparations may be subject to rapid release of their contents when taken with food, resulting in toxicity. It appears that consistent administration in the fasting state allows predictability of effects. 

Among the apatite substituents, carbonate has been the subject of many studies. The apatite present in dental enamel is not a pure HA, but rather a corbonate apatite with a carbonate content of 2—3 %. There is still a controversy about the location of the carbonate in enamel, dentine and bone. While most recent studies agree that carbonate appears to be substituting within the lattice rather than existing in an amorphous phase, there is still some disagreement as to the actual position of the carbonate. The presence and location of the carbonate in dental enamel may relate directly to the risk of carious attack. Carbonate has been shown to be leaked preferentially from early carious lesions81. ... 

The standard test method for proximate analysis (ASTM D-3172) covers the methods of analysis associated with the proximate analysis of coal and coke and is, in fact, a combination of the determination of each of three of the properties and calculation of a fourth. Moisture, volatile matter, and ash are all determined by subjecting the coal to prescribed temperature levels for prescribed time intervals. The losses of weight are, by stipulation, due to loss of moisture and, at the higher temperature, loss of volatile matter. The residue remaining after ignition at the final temperature is called ash. Fixed carbon is the difference of these three values summed and subtracted from 100. In low-volatile materials such as coke and anthracite coal, the fixed-carbon value equates approximately to the elemental carbon content of the sample. 

In Japan, NKK was the first company to use petroleum coke as the source for metallurgical coke making in 1967. Since then, petroleum coke has been utilized to increase carbon content and decrease ash content of coal blends used by Japanese iron and steel companies. This report includes the following subjects ... 

When discussing the oil produced, the subject of carbon becomes an issue. Carbon is formed during cracking of hydrocarbons at high temperature and pressure. This carbon is present in heavy oil and will be suspended within the oil. However, oil containing a small amount of carbon is easily combustible without any trouble. The carbon content is... 

The term pyrolytic carbon can be applied to carbon filaments, carbon blacks, and carbon films, as well as to the more massive deposits which are the subject of this section. Pyrocarbon materials, made by chemical vapor deposition (CVD), vary in density, properties, and structure as much as the bulk materials discussed in 17.3.4.1. A heated hydrocarbon gas decomposes into an entire series of molecular species with a wide spectrum of carbon contents and molecular weights Within this pyrolyzing atmosphere, droplets form that pyrolyze and condense on a nearby surface, or large carbonaceous complexes may condense directly on the surface of the chamber. The former condition produces a fluffy, sooty, soft carbon, not far removed from carbon black, while the latter produces a hard solid carbon. The second of these materials is of primary interest here. The structure of the carbon produced by the CVD process has been shown to depend on the type of hydrocabon and its concentration, the pyrolysis temperature, the contact time, and the geometry of the pyrolyzing chamber. Of these, the pyrolysis temperature is perhaps the most important, but it is the nature of the chamber that conveniently divides the carbons produced into two distinct types. 

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