Surface preparation sheet

An important newer use of fluorine is in the preparation of a polymer surface for adhesives (qv) or coatings (qv). In this apphcation the surfaces of a variety of polymers, eg, EPDM mbber, polyethylene—vinyl acetate foams, and mbber tine scrap, that are difficult or impossible to prepare by other methods are easily and quickly treated. Fluorine surface preparation, unlike wet-chemical surface treatment, does not generate large amounts of hazardous wastes and has been demonstrated to be much more effective than plasma or corona surface treatments. Figure 5 details the commercially available equipment for surface treating plastic components. Equipment to continuously treat fabrics, films, sheet foams, and other web materials is also available. 

Metal Preparation. Sheet-steel parts are formed by stamping, bending, and shearing. Many parts require welding (qv), which needs to be carried out in a uniform, smooth manner so that the welded joint can be enameled without defects. Cast-iron parts are formed by the usual cast-iron foundry methods however, additional care is given to prevent contamination of the surface. Surface contamination causes defects in the enamel, particularly bUsters and bubbles. Aluminum metal can be formed in sheets, extmsions, and as castings. 

The surface preparation operations for strip are dependent upon whether the basis material is steel or aluminum. The surface preparation steps for steel strip are minimal in comparison to porcelain enameling on steel sheets because precleaned strip steel is used. Steel strip is nickel immersion plated prior to the enameling step. Surface preparation for aluminum involves only cleaning. The enamel for either basis material is applied by means of spray guns that are aimed at the surface of the moving strip. Two coats are normally applied, the strip being fired after each coat. 

Test samples have been prepared from a 3 mm hot-rolled steel sheet which showed an intact mill scale (Degree A of Swedish Standards, SIS-055900), Thereafter they were shot blasted with S-280 to reach the ASa3 standard, prior to the application of the paint coating. Surface preparation B St 2 was obtained by wire brushing a steel sheet of Grade B obtained in turn by oxidation of Grade A sheet in a contaminant free atmosphere. In "Table I.", the characteristics of the paints used in this study are shown. 

Ultrasonic welding, used increasingly in the aerospace, automotive, electrical, and electronics industries. The process requires simpler surface preparation and less energy and allows welding of thinner sheets to thicker structural members. 

The most convenient method of preparing the lithium chips is as follows Pieces of lithium several grams each in size and slightly moist with parafifin oil are pounded with a hammer into thin sheets on a dry surface. The sheets are quickly cut into small chips by means of a pair of scissors and are added immediately to the absolute ether. 

Composite abrasive materials, such as Scotch-Brite (3M Company), have proved popular for mechanical surface preparation. These commercial abrasive materials are available in pad and sheet form, and they can conform easily to the shape of a surface. When combined with water flushing, they provide clean, almost oxide-free surfaces. Hand sanding, wire brushing, and other abrasion methods that are highly related to the operator s skill, and patience must be carefully controlled. These processes are a source of inconsistency and should be used only when no other method is possible. 

Gombert et al. have reported subwavelength structured antireflective surfaces prepared on glass by embossing a nickel master shim on acrylic siloxane layer with UV irradiation (Gombert et al., 1999). Hemispherical reflectance values of <1% are achieved for nonabsorbing planar sheet. 

The lap joint, in which two sheets are joined together with an overlay, is one of the most common joints encountered in practice. Joints of this type made from thin aluminium sheet 25 mm wide, 12 mm long (lin by 0-5 in) and 1-6 mm thick have long been used for quality control. The joint is easy to make and the results are sensitive to both adhesive quality and adherend surface preparation. 

Many adhesive suppliers indicate certification authority approval for marine use in their product data sheets. O Table 48.1 shows typical requirements. It is important to note that these tests are performed on adhesively bonded joints, usually in the form of lap shear specimens, and not bulk adhesives. The approval is therefore specified for particular substrates, and includes their surface preparation and the joint manufacturing procedure. 

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