Carbon core hardness

Examples of such surfactants are detergents which include calcium and magnesium sulfonates (RSOO)2M2+, phenates (RC6H40)2M2+, carboxylates (RCOO )2M2+, phosphonates RPO/M2 and carbonate-sulfonate hard-core reverse micelles (RMs). Ashless dispersants are the most widely used types, such as the substituted polyisobutylene amine succinimides (mono-substituted, m-PIBS and bis-substituted, b-PIBS), succinate esters, Mannich bases, and phosphorus types, see Chapter 2.2 for formulas (Inoue and Watanabe, 1983 Papke and Rubin, 1992 Vipper and Watanabe, 1981). 

The use of carbonate-benzenesulfonate hard-core RM additive drastically changes the build-up mechanisms and the resulting structure of the antiwear surface film. Considering these results, the main difference between the antiwear action of the ZDDP molecules and the hard-core RMs is clear. In the case of... 

The acid deactivation mechanism in hydrocarbon media is supplementary to the neutralizing action of carbonate-surfactant hard-core RMs. Traces of strong sulfur, nitrogen or halogen acids are scavenged by neutral detergents, with the... 

Modified hard-core RMs by phosphosulfurized compound. Improved extreme-pressure and antiwear properties have also been obtained with the introduction of some chemical species, such as sulfur, phosphorus or boron derivatives, into the colloidal core (Delfort et al., 1998 Inoue, 1993 Inoue and Nose, 1987). Welding loads, load wear index and wear scar diameter at 5 wt% of a CaC03 core surrounded by a calcium alkylaryl-sulfonate surfactant shell, and modified by phosphosulfurized calcium carbonate core were evaluated for calcium dialkyl dithiophosphate (CaDTP) and calcium trithiophosphate (CaTTP) with the four-ball extreme-pressure test (ASTM D2783 standard method). Both modified products exhibit improved extreme-pressure performances (welding load and load wear index), while their antiwear properties (wear scar diameter) compared to those of the original micellar substrate remain at least at the same level. 

It was proven that the carbonate-sulfonate hard-core RMs, but not the calcium carbonate powder, has an effect on acid neutralization and performance. The effective diameter of the micelles is 5 to 10 nm, and it is known that the smaller the size of the micelle, the greater its ability to neutralize acids. In order to develop high performance calcium carbonate in RMs, it is important to understand... 

Table 3.13. The effect of ZDDP, dispersant and carbonate-phenate hard-core RMs on the tribofilm formation in paraffinic oil (Willermet et al., 1995a)...

Calcium borate-detergent and calcium carbonate-detergent hard-core RMs Calcium borate is stabilized in hard-core RMs with detergents such as sulfonate, salicylate and phenate and evaluated in comparison with calcium carbonate-detergent RMs. The hydrolytic stability, oxidation stability, thermal stability, friction and wear characteristics of both systems are shown in Table 3.7. Why have borate-detergent RMs been recently recognized as an efficient multifunctional class of anticorrosive-antiwear additive ... 

Hard-core reverse micelles are composed of detergent molecules, e.g., calcium sulfonate strongly bonded to calcium carbonate core detergent layer of 2.2 nm, hard-core diameter of 3.9 nm, total diameter of 8.2 nm. 

Some examples of commercial products are MPG and ICG by Mitsubishi Chemical Co., GDA by Mitsui Mining Co., OMAC by Osaka Gas Chemical Co., 818 by BTR Energy Materials Co., NG-7 by Kansai Thermochemical Co., and DAG by Sodiff.656 Hard carbon coated cokes and soft carbon coated hard carbons are other carbons with core-shell structure reported in the literature.610-657... 

Recent laboratory studies have demonstrated the potential utility of borates as alkaline agents in chemical enhanced oil recovery. Compared with existing alkalis, sodium metaborate has an unusually high tolerance toward the hardness ions, Ca + and Mg +, paving the way for the implementation of alkali-surfactant-polymer floods for the large number of high-hardness saline carbonate reservoirs. In the absence of surfactants, borate solutions exhibit a strong tendency for spontaneous imbibition, or uptake into oil-wet or mixed-wet carbonate cores, with consequently improved recovery of oil compared with solutions of other salts and alkalis. 

Barium carbonate of finely controlled particle size reacts in the soHd state when heated with iron oxide to form barium ferrites. Magnetically aligned barium ferrite [11138-11-7] powder can be pressed and sintered into a hard-core permanent magnet which is used in many types of small motors. Alternatively, ground up magnetic powder can be compounded into plastic strips which are used in a variety of appHances as part of the closure mechanism. 

Tubercles consisted of hard, hlack oxide shells overlaid with friable carbonate-containing deposits. In places, several laminate black magnetite shells existed. The outer crust could be crushed by gentle pressure with a finger. Tubercles were riddled with white crystalline fibers. Other detritus was incorporated into the tubercle core and crust. Metal loss was less than 0.030 in. (0.076 cm) below each tubercle. Wall thickness was almost 0.25 in. (0.64 cm). 

Copper and the Copper Alloys. Copper and its alloys are relatively resistant to corrosion dry, unpolluted air rarely affects them at normal temperatures surfaces of the metal or its alloys exposed to polluted air, even under ordinary atmospheric conditions, however, are tarnished by pollutants such as hydrogen sulfide and/or carbon dioxide. Given sufficient time, the activity of the pollutants result in the formation of a usually green layer, known as patina, which coats and surrounds the bulk of the metal or alloy (see Fig. 40). If the patina is chemically stable, that is, if it is hard, is non-porous, and covers the entire surface of an object, it protects the underlying metal core from further corrosion. Such a patina consists mostly of basic... 

Primary glide occurs on the (111) planes. Shear of a carbon layer over a metal layer (or vice versa), when the core of a dislocation moves, severely disturbs the symmetry, thereby locally dissociating the compound. Therefore, the barrier to dislocation motion is the heat of formation, AHf (Gilman, 1970). The shear work is the applied shear stress, x times the molecular (bond) volume, V or xV. Thus, the shear stress is proportional to AHf/V, and the hardness number is expected to be proportional to the shear stress. Figure 10.2 shows that this is indeed the case for the six prototype carbides. 

Typical forms of the radial distribution function are shown in Fig. 38 for a liquid of hard core and of Lennard—Jones spheres (using the Percus— Yevick approximation) [447, 449] and Fig. 44 for carbon tetrachloride [452a]. Significant departures from unity are evident over considerable distances. The successive maxima and minima in g(r) correspond to essentially contact packing, but with small-scale orientational variation and to significant voids or large-scale orientational variation in the liquid structure, respectively. Such factors influence the relative location of reactants within a solvent and make the incorporation of the potential of mean force a necessity. 

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