Disilicates

Earlier formulations contained mainly chlorine bleach, metasiUcates, triphosphate, and nonionic surfactants. Modem manufacturers have switched to more compHcated formulations with disiUcates, phosphates or citrate, phosphonates, polycarboxylates, nonionic surfactants, oxygen bleach, bleach activator, and enzymes. The replacement of metasiUcates by disilicates lowers pH from approximately 12 to 10.5, at 1 g ADD/L water. The combined effect of decreased pH, the absence of hypochlorite, and the trend toward lower wash temperatures has paved the way for the introduction of enzymes into ADDs. Most ADD brands in Europe are part of the new generation of ADD products with enzymes. The new formulations are described in the patent hterature (55—57). 

Disilicates, containing the discrete Si207 ) unit, are rare. One example is the mineral thortveitite, Sc2Si207, which features octahedral Sc " (r 75 pm) and a linear Si O Si bond between staggered tetrahedra (Fig. 9.4a). There is also a series of lanthanoid disilicates I.n2Si207 in which the Si-O-Si angle decreases progre.ssively... 

Silica deposition in the temperature range of 500 to 700 °F (260-371 °C) is primarily sodium disilicate [Na6(Si207)2 alternatively given the formula fJ-Na Oj]... 

Utilizing this description of silicate glass formation, we suggest models to explain the incorporation of 4+ and 6+ actinide ions in sodium disilicate glass. During cooldown,... 

In contrast, disilicate glasses containing U 4+ showed much less leach resistance. The 4+ glass was only slightly more leach resistant than pure sodium disilicate glass which is water soluble. For 4+ glasses, the ph of the leach solution... 

C09-0080. The second simplest silicate is the disilicate anion, Si2 O7 , in which one oxygen bridges... 

Figure 1. Structures of (a) orthosilicate, (b) disilicate, (c) cyclotrisilicate, and (d) cyclohexasilicate ions.

In the route used in this work, a monomeric or oligomeric silicate is protonated, the resulting silicic acid is esterified, and the alkyl silicate is organodealkoxylated. In each step, the siloxane framework is fully or substantially preserved. For the case starting with a metal disilicate the reactions can be represented as ... 

The structure formed by two tetrahedral units joined at a corner is known as the pyrosilicate or disilicate ion (see Figure 14.1b). 

Alkali aluminate (5-calcium disilicate monosulfate), phase in Portland cement clinker, 5 472t Alkali aluminate (8-calcium disodium trialuminate), phase in Portland cement clinker, 5 472t Alkali belite, phase in Portland cement clinker, 5 472t Alkali blue toners, 14 318 Alkali borate glasses, 12 572, 573, 584 Alkali catalysed pad-dry-bake procedure, 9 485... 

Calcium cyanamid process, for ammonia synthesis, 11 114, 115 Calcium cyanide, 8 194-197 Calcium cyanide diammoniate, 8 195 Calcium dichromate, molecular formula, properties, and uses, 6 561t 5-Calcium disilicate monosulfate, phase in Portland cement clinker, 5 472t 5-Calcium disilicate monocarbonate, phase in Portland cement clinker, 5 472t Calcium disilicide, 4 530 8-Calcium disodium trialuminate, phase in Portland cement clinker, 5 472t Calcium doping, 23 842-844 Calcium P-alumina, 2 406t Calcium ethylenediaminetetraacetate, 7 596t... 

Spunbonded processes, 17 463 Spunbonded structures, novel, 17 466 Spunbound fibers, 11 236, 240-241 Spun fibers, 16 18, 20 Spunlaced nonwovens, 17 507 Spunlace fabrics, production of, 17 516 Spun yarn, 11 177, 178, 250. See also Yarn spinning technologies crystalline structure of, 11 237-238 Spurrite (5-calcium disilicate monocarbonate)... 

The biszwitterionic A5 Si, A5 Si -disilicate 71 was prepared according to Scheme 14 (solvent acetone/water, room temperature) and isolated, after crystallization from water, as the octahydrate meso-11 8H20. 

The biszwitterionic A5Si,A5Si -disilicates 72-74 were synthesized according to Scheme 15 in water (72, 73) or methanol (74) at room temperature. For these syntheses, the following tartaric acids were used 72, (R,R)-... 

NMR studies H, 13C, 29Si) demonstrated that the zwitterionic 5Si-silicates 53-60 and 63-70 and the biszwitterionic A5Si, A5Si -disilicates 72-74... 

Oligosilicates monosilicates, disilicates, trisilicates, tetrasilicates Cyclosilicates monocyclosilicates, dicyclosilicates... 

Figure 4-3 Experimental data on nucleation rate in lithium disilicate melt (points) compared to theory. The solid curve is a fit to the experimental data. The short dashed curve (middle curve) is the theoretically calculated curve multiplied by 1.7 xlO °. Parameters used in calculating the theoretical curve using Equation 4-9 Te=1306K, a O.ZOlJ/m, l c = 61.2cm /mol, AHm-c = 61.1 kj/mol, = (Neilson and Weinberg, 1979). The long...

Fuss T., Ray C.S., Lesher C.E., and Day D.E. (2006) In situ crystallization of lithium disilicate glass effort of pressure on crystal growth rate. /. Non-Cryst. Solids 352, 2073-2081. 

Neilson G.F. and Weinberg M.C. (1979) A test of classical nucleation theory crystal nu-cleation of lithium disilicate glass. /. Non-Cryst. Solids 34, 137-147. 

Black lamps A black lamp is a low-pressure mercury lamp whose envelope is covered with a phosphor such as strontium fluoroborate or barium disilicate. The type of phosphor determines the spectral distribution of the lamp output (Forbes et al., 1976). Figure 16.4 shows a typical spectral distribution for A < 500 nm from a black lamp as well as the solar... 

---