Values for silicate

The C stars are another case their average mass loss is slightly more than 10 times the value for solar-type stars with the same atmospheric parameters. This must indicate that C-star mass loss is dust-driven, for the driving efficiency of Carbon dust particles is about ten times the value for silicates (sedlmayr, private comm. 1987). 

If the waste is isolated in a geologic repository, the iodine form should be stable to at least 100°C and possibly at 250°C depending on the repository site. If the waste form satisfies the thermal stability requirement, the most likely release mechanism then becomes leaching in the event that groundwater contacts the immobilization form. Allard et al. (11) report log Kd values for silicate minerals ranging from -0.5 to -3.5. Fried et al. (12) found little retention of iodine (as iodide or iodate) by Los Alamos Tuff. Thus, once the Iodine has been removed by leaching, it will potentially move at the same velocity as the groundwater. 

Newton, M.D. and Gibbs, G.V., Ab initio calculated geometries and charge distributions for H4Si04 and H6Si2Ov compared with experimental values for silicates and siloxanes, Phys. Chem. Miner., 6, 221, 1980. 

Max. value for silicate 350 mmol/m corresponding to 20 mg/1 calculated as silicon dioxide in treated drinking water ... 

Table 10. Interfacial Tension Values for Silicate-Surfactant Systems...

Elastic modulus Up to the fracture stress, glass behaves, for most practical purposes, as an elastic solid at ordinary temperatures. Most silicate-based commercial glasses display an elastic modulus of about 70GNm", i.e. about 1/3 the value for steel. If stress is applied at temperatures near the annealing range, then delayed elastic effects will be observed and viscous flow may lead to permanent deformation. 

Fracture toughness values for glass polyalkenoate cement vary from 0-25 to 0-55 MN (Lloyd Mitchell, 1984 Goldman, 1985 Lloyd Adamson, 1987). The values are generally higher than those found for the traditional dental silicate cement but lower than those found for anterior composite resins (Lloyd Mitchell, 1984 Goldman, 1985) and much lower than those for posterior composite resins and dental amalgams (Lloyd Adamson, 1987). 

Sulfur isotopic data of separated pyrite as the commonest sulfide mineral (Kajiwara, 1971 Kajiwara and Date, 1971) show different values for the three sub-types of Horikoshi and Shikazono (1978). The values of pyrite in the C sub-type deposits are higher than the values of pyrite from the Y and B sub-types. The values of pyrite from the Y sub-type seem to be slightly higher than those from the B sub-type. Kajiwara and Date (1971) are of a different opinion the values from the Kosaka district are higher than those in the Hanaoka district, because all sulfur isotopic data from the C sub-type were obtained in the Kosaka district. The sulfur isotopic data on the obtained Uwamuki deposits of the B sub-type in the Hanaoka district indicate systematic decrease in 8 S passing from the yellow ore (4-7%o) to the black siliceous ore (4-5%c) (Bryndzia et al., 1983). Kajiwara and Date s data (1971) include three values of pyrite in the Doyashiki deposit of C sub-type in the Hanaoka district. The main Doyashiki... 

It is very difficult to obtain values for the intrinsic hardnesses of silicate and related types of glass. Therefore, no attempts at quantitative analyses will be made here. A semi-empirical method has been proposed by Yamane and Mackenzie (1974) based on the geometric mean of bond strength relative to silica, shear modulus, and bulk modulus. For 50 silicate glasses it yields estimates within ten percent of measured values, and for a few non-silicate glasses it is quite successful, as Figure 14.2 indicates. 

Table 1.22 Optical (a ) and static (a polarizabilities for silicates. Calculated values obtained by additivity principle starting from polarizability of oxide constituents (adapted from Lasaga and Cygan, 1982). ...

Table 3.8 lists values of ajj and reference cation for silicates and aluminates. The tabulated parameters, as simple interpolation factors, have good correlation coefficients, confirming the quality of the regression. 

Table 3,8 Regression parameters A O for silicates and aluminates. Values in kJ/mole (from Tardy and Garrels, 1976, 1977 Tardy and Viellard, 1977 Tardy and Gartner, 1977).

In polymeric models for silicate melts, it is postulated that, at each composition, for given values of P and T, the melt is characterized by an equilibrium distribution of several ionic species of oxygen, metal cations, and ionic polymers of monomeric units SiOt. ... 

Figures 10.9S(a,b) show isopleths calculated between (a) corium and siliceous concrete and (b) corium and limestone concrete. Comparison between experimental (Roche et al. 1993) and calculated values for the solidus are in reasonable agreement, but two of the calculated liquidus values are substantially different. However, as the solidus temperature is more critical in the process, the calculations can clearly provide quite good-quality data for use in subsequent process simulations. Solidus values are critical factors in controlling the extent of crust formation between the melt-concrete and melt-atmosphere interface, which can lead to thermal insulation and so produce higher melt temperatures. Also the solidus, and proportions of liquid and solid as a function of temperature, are important input parameters into other software codes which model thermal hydraulic progression and viscosity of the melt (Cole et al. 1984).

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