Silica flatting

Fig. VI-3. Attraction between fused-silica flat plates and spheres of radius 413.5 cm (I) or 83.75 cm (II). The lines are drawn with a slope of -3.00. (From Ref. 27.)...

FIG. 4 Experimental force curves for a silica sphere interacting with a polished silica flat surface in the presence of simple electrolytes (concentrations as indicated) measured using an AFM. (Adapted from Ref. 29.)... 

Film spectra were taken using thin films of polymer spun-cast on 1.6 mm thick fused silica flats, 25 x 25 mm square. All film samples were cast from xylene which had been previously dried over i)A molecular sieves. For the solution spectra, toluene was used after distillation from NaK alloy under Ar. The alkane solvents were obtained from a variety of sources and used without further purification. 

Tixosil. [Rhone-Poulenc] Hydrated silica flatting agents, rheology control agents fcu coatings, adhesives, plastics, paper, food, cosmetics, toothpaste, and pharmaceutical applies. 

Chem. Descrip. 18% Silica (flatting agent), 27% med. oil alkyd resin (vehicle), 55% Rule 66 mineral spirits (solv.)... 

Linevol Plasticizer alcohol. Shell Lite-Tak UV adhesives, Loctite Lo-Vol Silica flatting agents, PPG Lamod Copolyester elastomer, GE Lucite Methyl methacrylate, GE Lupersol Liquid organic peroxide. Elf Atochem... 

Typically specimens for reflectivity measurements are prepared on flat, smooth, rigid substrates. For example, these substrates can be polished fused silica, quartz, or silicon. It is important, however, that the substrates be thick to avoid distonions of the specimen when mounted in the reflectometer. Any curvature or bowing will increase the divergence of the incident beam and result in a deterioration of the resolution. 

In general, a Raman adsorption cell consists of a length of pyrex or silica tubing, one end of which is sealed with an optical flat, and the other either connected to a gas line for admitting the adsorbate or to a vacuum line for evacuating the cell. Activation of the samples may then be carried out in situ 27). 

Silica can also etch gauge glass, thus making it difficult to observe the water level. As a result, special flat gauge glass is used for boilers operating at over 250 psig. 

The silica him thickness was determined as a function of the disk radius by an optical interference method using the spectrometer. A steel ball was loaded against the silica surface to obtain an interference pattern of a central, circular Hertzian area with surrounding circular fringes due to the air gap between the deformed ball and flat. The thickness of... 

Ludwig KR, Paces JB (2002) Uranitrm-series dating of pedogenic silica and carbonate. Crater Flat, Nevada. Geochim Cosmochim Acta 66 487-506... 

The electrochemical cells employed in epr measurements are generally fabricated out of silica since glass contains paramagnetic impurities that can interfere with the signal. The need to minimise the interaction of the sample with the electric component of the radiation in the cavity, and the geometry and size of the cavity itself, have generally led to electrochemists employing flat cells that are c. <0.5mm thick. 

The difference between this technique and GC or HPLC is that the separation process occurs on a flat essentially two-dimensional surface. The separated components are not usually eluted from the surface but are examined in situ. Alternatively, they can be removed mechanically for further analysis. In thin-layer chromatography (TLC), the stationary phase is usually a polar solid such as silica gel or alumina which is coated onto a sheet of glass, plastic, or aluminium. Although some moisture is retained by the stationary phase, the separation process is predominantly one of surface adsorption. Thin layers are sometimes made from ion-exchange or gelpermeation materials. In these cases the sorption process would be ion-exchange or exclusion. 

---