Impregnation process

Two processes may be used in the manufacture of combustible cases the original post-impregnation process and the more recently and more widely employed beater additive process. The processes differ primarily in the point at which the required resin is added to the composition. A schematic of the beater additive process is shown in Figure 11. 

In most cases, the impregnation process is followed by an electrochemical formation where the plaques are assembled into large temporary cells filled with 20—30% sodium hydroxide solution, subjected to 1—3 charge—discharge cycles, and subsequentiy washed and dried. This eliminates nitrates and poorly adherent particles. It also increases the effective surface area of the active materials. 

To add surface area, the supports are uniformly coated with a slurry of gamma-alumina and recalcined under moderate conditions. The wash coat acts to accept the active metals, typically low levels of platinum and palladium, in a conventional impregnation process. In the United States in passenger car apphcations the spherical catalyst is used almost exclusively, and methods have been developed to replace the catalyst without removing the converter shell when vehicle inspection reveals that emission standards are not met. 

A second library of six catalysts, shown in Table 2, codes FI to F6, was prepared to examine the effect of varying the method and sequence used for the impregnation process in this series, the samples contained only Mo and V at nominally identical concentrations (with a ratio Mo/V of ca. 6), with V approx 1% (but not comparable with previous series). Two additional samples, F7 and F8, were prepared to show any effects of including Nb and W (each in amount of ca. 1%) in this formulation. 

Xu X, Jiang Z, Fan X, and Xia C. LSM-SDC electrodes fabricated with an ion-impregnating process for SOFCs with doped ceria electrolytes. Solid State Ionics 2006 177 2113-2117. 

Treu, A., Habicht, J., Klaucke, R. and MiRtz, H. (2003). Improvement of wood properties by a combined impregnation process— the Royal process. In Proceedings of the First European Conference on Wood Modification, Ghent, Belgium, Van Acker, J. and HiU, C.A.S. (Eds.), pp. 3-14. 

The traditional method for generating nanoparticles in mesoporous materials includes a wet impregnation process, followed by treatment with heat, reducing reagents or oxidation. This method could be applied to a lot of metals [43, 61] or metal oxides [50, 59], Other... 

It is not yet known how efficient this impregnation process is, and much more work will be necessary to obtain quantitative data. Nevertheless, preliminary results suggest that, with further work, direct comparisons with pore distributions as recorded by the BET method, for example, may be possible. 

In order to overcome the main limitations of the impregnation processes, connected to the limited solubility of the compounds in the supercritical fluids, Perman [68] proposed an alternative method. A supercritical impregnation process was coupled with a liquid solvent (preferentially water) to enhance the drug solubilization. The system composed of a liquid drug solution and the polymeric support was pressurized with the supercritical fluid. Consequently, the swelled polymer allows rapid diffusional transport of the solute into the polymeric substrate. In different examples, bovine serum albumin microspheres were impregnated with insulin, trypsin and gentamicin (see Table 9.9-5). 

This is a process designed to cover a catalyst support, such as silica, alumina, mesoporous molecular sieves, or other supports with a metallic catalyst, or other catalytically active materials. The process is carried out by contacting the solid support, for a precise time, with a solution containing the active elements, to introduce a solution of the precursor into the pores of the support. During the impregnation process, the support can be completely free of the solvent when the precursor is dissolved. In this... 

Fiber reinforced plastics (FRP) are widely utilized now for a number of cryogenic applications. The matrices used are generally thermosetting resins such as epoxies, polyesters and phenolics, since they are easy to apply in impregnating processes. 

In the overall impregnation process the following important facts should be noted ... 

Addition of Blowing Agents to Styrene Solutions of Polystyrene. If the pentane is added to a suspension polymerization of styrene after the bead identity point has been reached, the formation of blisters is avoided and the diffusion of pentane into the bead is rapid. Thus, the two objections to the pentane-in-monomer process and the post-polymerization impregnation processes are avoided (31, 119). The same system has also been used to introduce normally gaseous blowing agents, such as butane, propane, st/m-dichlorotetrafluoroethane, propylene, butene, and butadiene (51, 91,115). 

Processes for fabrication of carbon/carbon composites by "gas-phase impregnation" and by "liquid-phase impregnation" were described in the 1975 Symposium (JJ. The vapor impregnation process was first used for fabrication of the special aircraft brakes required for the commercial jet CONCORDE, and is still in use, although most new carbon/carbon parts and even aircraft brakes are now produced by the more economical pitch-impregnation processes. 

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