Electroplating continued metallic

A number of companies offer metallized fluoroplastic films. For example, Sheldahl Corp. provides a family of metallized FEP films as shown in Table 14.13. WL Gore markets a metallized film, based on its Gore-Tex film, which is selectively image-metallized and has a continuous metal phase in the direction of the z-axis (thickness). Crane Polyflonmarkets electroplated PTFE shaped articles for applications such as micro-wave communications and magnetic resonance imaging (MRI).[129]... 

The depressed prices of most metals in world markets in the 1980s and early 1990s have slowed the development of new metal extraction processes, although the search for improved extractants continues. There is a growing interest in the use of extraction for recovery of metals from effluent streams, for example the wastes from pickling plants and electroplating (qv) plants (276). Recovery of metals from Hquid effluent has been reviewed (277), and an AM-MAR concept for metal waste recovery has recentiy been reported (278). Possible appHcations exist in this area for Hquid membrane extraction (88) as weU as conventional extraction. Other schemes proposed for effluent treatment are a wetted fiber extraction process (279) and the use of two-phase aqueous extraction (280). 

Specification for electroplated coatings of 65/35 tin/nickel alloy Method for the evaluation of results of accelerated corrosion tests on metallic coatings Methods of test for paints Cross-cut test Pull-off test for adhesion Resistance to artificial weathering (enclosed carbon arc) and Addendum No. 1 Resistance to continuous salt spray Notes for guidance on the conduct of natural weathering test... 

Metallization can be applied by batch or continuous vacuum metallizing, sputtering and electroplating. 

The sheer amount of material deposited on a cathode is of less practical significance than the distribution of the deposit over the cathode and its thickness. Indeed, it ought to be understood that in practice metal ions cannot be expected to and do not deposit as continuous sheets from one edge of the cathode to the other. Rather, metal ions become attached to the cathode at certain favored sites. The result of this is the possible presence of discontinuities in the form of pores, cracks, or other irregularities. Thus, in electroplating, current density and its distribution play a centrally important role in determining the quality of the final deposit. Defined in terms of the actual electrodeposition setup or process, the current density is the total current divided by the area of the electrode. 

Typically, coatings most often in use as intermediate layers are silver, nickel, copper, and gold however, silver is used by far the most often. This is so because of the low dissociation temperature of silver oxide, making it relatively easy to obtain clean surfaces. Also, the typical thickness range of electroplates used, in practice, for diffusion welding is about 15 to 40/rm, but thicknesses as great as 130 )um must sometimes be used. A considerable variety of steel types as well as aluminum and a host of other difficult-to-join metals and even beryllium have been and continue to be diffusion bonded with the use of electroplated intermediate layers. 

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