Surface, vacuum, cleaning stripping

Stripping is the removal of thick deposits on a surface. For example, stripping is used to remove thick oxide layers by pickling and to rework coated substrates, as well to clean fixtures and removable vacuum surfaces. Table 3.11 fists a number of stripping chemicals for removing deposits from substrates, fixtures, and other surfaces. 

The vacuum extraction process involves using vapor extraction wells alone or in combination with air injection wells. Vacuum blowers are used to create the movement of air through the soil. The air flow strips the VOCs from the soil and carries them to the surface. Figure 18.14 shows the flow diagram for such a process. During extraction, water may also be extracted along with vapor. The mixture should be sent to a liquid-vapor separator. The separation process results in both liquid and vapor residuals that require further treatment. Carbon adsorption is used to treat the vapor and water streams, leaving clean water and air for release, and spent GAC for reuse or disposal. Air emissions from the system are typically controlled by adsorption of the volatiles onto activated carbon, by thermal destruction, or by condensation. 

The gold coating on the as-supplied silicon nitride cantilevers is stripped with aqua regia and a clean (111) oriented gold surface is then deposited by vacuum evaporation on the tip side of the lever. The gold film deposition is carried out at a pressure of less than 10 mbar and at a temperature of 270 C and the films are then annealed at the same temperature for 4 h before being allowed to cool down slowly (Balzers UTT400... 

The basic cleaning procedure is quite simple. The thick lacquer coating is applied to the precleaned surface with a brush or by dipping. The parts are then allowed to dry completely. In a subsequent operation, performed in a laminar flow box to prevent recontamination, the lacquer film is stripped off. Stripping is easier if a wire loop is embedded in the coating. Attempts to strip off the film in vacuum prior to thin-film deposition were only partly successful because of the difficulty in detecting surface residues inside the evacuated system. 

In the preparation of the polymer films used in this work, the procedure entailed pressing the high density polyethylene powder between clean sheets of aluminum foil. The aluminum foil was then stripped from the surface. In previous ESCA studies, we have investigated in detail the surface of aluminum foil. The main points which emerge from these studies are that the oxide layer in commercially produced annealed (domestic) foil is typically -20A thick and that a tenaciously held hydrocarbon type layer is present at the surface which is not readily removed by either degreasing treatment or heating under very high vacuum conditions. 

Vacuum-abrasive cleaning No dust No clean-up Performs on all paints Requires waste disposal More expensive than chemical stripping Performs marginally on odd-shaped surfaces Requires skilled labor... 

Chemical paint stripping is recommended where it is cost effective. Vacuum-abrasive cleaning should follow chemical paint stripping and heat gun treatment because a residual amount of lead remains on the substrate with the two latter methods. If the heat gun treatment is not carefully controlled, the paint may become too hot, causing the paint to decompose and produce fumes as a result, lead particles enter the atmosphere. Most interior surfaces are particle board, wood, or sheet rock. A test patch should be made to determine... 

Mechanical brushing or mechanical activation of metal surfaces just prior to film deposition is a technique that produces improved adhesion of vacuum-deposited coatings on strip steel. The mechanical brushing disrupts the oxide layer, exposing a clean metal surface. 

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