W/b ratio

Boron W + B (amorphous) powder mixture compacts SOO C inHj/l hour 800-1200 °C in Ar/2 hours Individual boride formation depends on W/B ratio W2B, WB, W2B3, WB4... 

PR By solid state reaction between W and amorphous B powder pressed in compacts at elevated temperature pretreatment at 500 °C in hydrogen for 1 horn followed by 800-1200 °C in argon for 2 hours. The formation of the individual boride depends on the W/B ratio. 

Variable Cement w/b-ratio Condition Mean value... 

To measure the hydration heat release process of binder, the auto isothermal calorimeter of TAM Air was used. Tests were conducted using binder of 10 g and w/b ratio of 0.40 and the test temperature was 25 °C. 

That last measure merits more detailed description. Internal desiccation of concretes with low values of w/b ratio may be reduced by application of pre-soaked lightweight aggregate (LWA) grains or super-absorbent polymers (SAP) as water reservoirs. Such particles are dispersed in bulk concrete and water is used gradually for cement hydration, thus acting in a somewhat intelligent way. 

Tested super sulfated cements comprise mainly recycled industrial by-products blast furnace slag (Table 1) and heat-activated chemical gypsum, Kerysten K Co (the estimated CO2 balance (excluding transport) is 50 kg/t of manufactured SSC). Tests were conducted on the basis of standard mortar (binder/sand mass ratio = 1/3) with two W/B ratios (0.4 and 0.5), which correspond to characteristics of the old and new standards for SSC. 

The formulation of the selected SSC (C cement content) was used as a reference for comparison with an identical SSC but formulated with non-activated chemical gypsum (NAG). The performance levels achieved (Table 3) were lower than those observed in the case of heat-activated gypsum, whatever the W/B ratios used. 

A variety of materials, ranging from mineral binders to polymers, can be used as binder. However, materials based on polymers, such as epoxy or polyester resins, which are often used for concrete structures, should undergo careful assessment before use in historical masonry, due to possible issues regarding the mechanical and physical compatibility. Much more common for the repair of historical buildings are mineral binder systems based on cement or hydraulic lime with the addition of admixtures and fillers or aggregate. To inject bore holes, usually pure water/binder systems are used with typical w/b values of 0.8-1.0. However, the w/b ratio has to be adjusted according to the volume to be injected and to the moisture content of the substrate. 

Ternary Nitrides as Diffusion Barriers. Barrier layers with good step coverage and low resistivity are formed from ternary nitrides with various compositions Ti-Si-N, W-Si-N, and W-B-N. They are deposited by MOCVD with deposition temperatures between 300 and 450°C. Complete step coverage is obtained on reentrant features as low as 0.25 micron with an aspect ratio of 4.0.Pi]... 

Figure 2. Calcium-nitrogen ratio of the nonepiphyseal parts of the human femur during development. (Reproduced with permission from Ref. 1. Copyright 1965 W. B. Saunders Company.)...

Figure 6 A Platzman plot of the ratio of the secondary electron cross sections for ionization of N2 by electrons to the comparable Rutherford cross sections. Q is the energy loss, Q = W+B, and is equivalent to the parameter E used in the text. (From Ref. 44.)...

The mutual solubility Of two salts.—Numerous investigations have been made on this subject in the light of the phase rule by H. W. B. Roozeboom 8 and others. C. E. Linebarger also submitted mixtures of two salts to the action of various organic liquids in which one of the salts was insoluble. If both salts passed into soln. in a molecular ratio, it was assumed that a double salt is formed in soln. With a mixture of sodium and mercuric chlorides no double salt was formed with benzene or acetone as solvent, but with acetic ether, a salt, (HgCl2)2NaCl, was formed similarly also with lithium and mercuric chlorides, the salt HgCl2.LiCl was formed but no double salt was observed with potassium and mercuric chlorides in the same solvent. 

Figure 16.2 Double-potential-step chronoamperometry of 4.6 mM [Fe(CO)2(r)5-Cp)]2 in 0.1 M Bu4NPF6/propionitrile at -43°C. Step time Texp = 0.1 s. (A) Current transients for potential step from -0.8 to -1.9 V in blank electrolyte solution (thin line) and with added [Fe(CO)2(rj5-Cp)]2 (dark line). (B) Ratio of experimental currents -i(t + texp)/i(t) for 0 < t < Texp versus normalized time (t/texp) compared to theory (solid line) for kobs = 10.5 s 1. Electrode area = 0.0032 cm2. [Reprinted with permission from E.F. Dalton, S. Ching, and R.W. Murray, Inorg. Chem. 30 2642 (1991). Copyright 1991 American Chemical Society.]...

For example, when the indicator was colored in water the authors define a stoichiometric color intensity relative to water 7W = Cw/Ca, where Ca and Cw are the stoichiometric concentrations of indicator in solution A and in water. On the other hand, the specific color intensity of the colored form relative to water is defined as Sw = [B]w/[B]a, where [B]w is the concentration of the colored base in water and [B]ais concentration in solution A. Because the indicator exists only in its basic form in water, [B]w = Cw and in solution A, Ca = [B]a+ [BH+]a. The ionization ratio is given by Eq. (1.22). 

Relative sizes of ions and the degree of covalence are important in determining structures of MX compounds. Mooser and Pearson plotted the average principal quantum number of the ions vs. the difference in electronegativites of the elements to give reasonable separation of CsCl, NaCl, ZnS (hep), and ZnS (ccp) structures. (E. Mooser and W.B. Pearson, Acta Crystallogy 1959 12 1015.) This plot is more successful than the radius ratio plots. 

The disperse phase ratio can be critical if significant increases in drop size are required to suppress spray drift. Using fairly large nozzles, such as Allman No. 9, a w/o ratio of about 10 1 will be required with Formulations A and B, while Formulation C is unlikely to suppress drift, even at the highest phase ratio used. 

Here, again, A = W/B is the aspect ratio of the duct cross-section. 

Fogle, A. W, B. J. Barfield, and V. P. Evangelou. 1991. Solution sodium/caicium ratio effects on bentonite floe density. J. Env. Sci. Health. A266 1003-1012. 

The essential input data are (a) the bulk chemical composition of the cement, (b) the quantitative phase composition of the cement and the chemical compositions of its individual phases, (c) the fraction of each phase that has reacted, (d) the w/c ratio, (e) the COj content of the paste and an estimate of how it is distributed among phases, and (0 the composition of each hydrated phase for the specified drying condition. If (b) is unknown, it may be estimated as described in Section 4.4, and if (c) is unknown, it may be estimated from the age as described by Parrott and Killoh (P30), or, more simply though less precisely, by using empirical equations (D12,T37). If the phase composition by volume and porosities are to be calculated, densities of phases are also required. 

Target , M. J., Retallick, W. B., and Churchill, S. W., Flow through curved rectangular channels of large aspect ratio. AIChE. J. 41(5), 1061 (1995). 

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