Vacuum materials

AHam across water AHam across vacuum Material (zj) (zj)... 

V-Methylpropionamide can be dried over CaO. Water and unreacted propionic acid are removed as their xylene azeotropes. It is then distilled in a vacuum. Material used as an electrolyte solvent (specific conductance less than 10 ohm l cm ) is obtained by fractional distillation under reduced pressure, and storage over BaO or molecular sieves because it readily absorbs moisture from the atmosphere on prolonged storage. [Hoover Pure Appl Chem 37 581 1974, Recommended Methods for Purification of Solvents and Tests for Impurities, Coetzee Ed., Pergamon Press, 1982, Beilstein 4 IV 183.]... 

All of the experiments have been carried out under high vacuum. Materials have been purified according to standard procedures (12) kinetic measurements by dllatometry have been described elsewhere (,9) as well as the polymerization procedure. 

WG Perkins, Permeation and outgassing of vacuum materials . Journal of Vacuum Science and Technology, vol. 10, 1973, pp. 543-56. 

Figure 14. Reflectivity functions for two double layer samples with different air/film (uppermost layer) surface roughness mimicking the type of layers in a GIXAS cell geometry. The high frequency oscillations are finite thickness oscillations due to the second 1 pm water layer. Substrate (quartz)/water and water/film interfaces have rms roughness = 0.0. X-ray energy is 7100 eV. The arrows indicate the approximate positions of the vacuum/material interface critical reflectivity angles for the different layer materials.

Silica powder was pressed to form a pellet, and then treated with the silanes for periods of 10 to 20 hours at room temperature. The liquids were then decanted and the pellets were dried under vacuum. Material remaining on the silica surface can be regarded as chemisorbed, because the drying process removes substantially all material physically adsorbed on the surface. ... 

Processing Thick Film and Bulk Hybrids. After stirring the transparent hybrid solution for at least 4 days, a sample was removed and volatile materials were allowed to evaporate to near dryness at room temperature. The sample was then annealed at 60 °C under vacuum. Materials with different structures were obtained depending on the composition and treatment of the precursor solution. Under the right conditions, freestanding transparent films with thicknesses of 1-5 mm were obtained which were hard but not brittle. High concentrations of TEOS combined with fast evaporation of... 

Aluminum is an attractive metal to use as a vacuum material because of its ease of fabrication, light weight, and high thermal conduchvity. However, the natural oxide that forms on aluminum and thickens with time is rather porous and can give appreciable outgassing. Mill-rolled aluminum has an outgassing rate -100 hmes that of mill-rolled stainless steel. Aluminum is not normally used for vacuum processing systems because it is soft and easily corroded. 

N. Kaufherr, A. Krauss, D.M. Gruen, R. Nielsen, Chemical cleaning of aluminum alloy surfaces for use as vacuum material in synchrotron light sources, J. Vac. Sci. Technol. 

Technical Background ofVacuum Technology 3.1.3.1 Ultrahigh Vacuum Materials... 

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