Plated Metals

Fluoroboric acid is used as a stripping solution for the removal of solder and plated metals from less active substrates. A number of fluoroborate plating baths (27) require pH adjustment with fluoroboric acid (see Electroplating). 

The most common fused salt baths are complex mixtures of alkah chlorides, rigorously purified and dried. Fused salt plating must be done under an inert atmosphere. Often argon is used because nitrogen can react with some metals. Inert anodes, eg, Pt-coated titanium or graphite, are used and the plating metal is suppHed by additions of an appropriate metal salt. 

Aqueous Electrodeposition. The theory of electro deposition is well known (see Electroplating). Of the numerous metals used in electro deposition, only 10 have been reduced to large-scale commercial practice. The most commonly plated metals are chromium, nickel, copper, zinc, rhodium, silver, cadmium, tin, and gold, followed by the less frequendy plated metals iron, cesium, platinum, and palladium, and the infrequendy plated metals indium, mthenium, and rhenium. Of these, only platinum, rhodium, iddium, and rhenium are refractory. 

Electroplated materials are generally employed for a specific property or function. There is, of course, some ovedap for example, decorative use certainly requires some degree of corrosion resistance. The various usages and the principal plating metals employed are as hsted. There are also smaller amounts of other metals and alloys used for specific apphcations. 

Ductility Tests. The ductihty of plated metals differs considerably from the corresponding thermally cast metals. Additionally, ductihty which is an important property if parts are to be deformed after plating, varies with the chemical composition of the plating solution, as well as the operating conditions of a given plating process. Ductihty can also be important when plated parts are stressed in use. Some metal deposits have coefficients of... 

S. Nakahara, Y. Okiaaka, and H. Strashil, Ductility of Plated Metal Eilms Its Measurement and Relationship to Microstructure, ia Ref. 47. 

A.STM B636, Std. Methodfor Measurement of Internal Stress of Plated Metallic Coatings with the Spiral Contractometer, American Society for Testing and... 

Example 11 Pressure Drop Sieve Plate For the conditions of Example 10, estimate the pressure drop for flow across one plate. The thickness of the plate metal is 2 mm and the hole diameter is 4.8 mm. The superficial F-factor is 2.08 m/s(kg/m ) . 

McMordie, B.G., Impact of Smooth Coatings on the Efficiency of Modern Turbomachinery, 2000 Aerospace/Airline Plating Metal Finishing Forum Cincinnati, Ohio, March 2000. 

Corrosion potentials in plating baths The standing potentials of steel and copper (before application of current) are shown in Table 12.2, together with the standing potential of the plated metal and the potential below which hydrogen should, in theory, be evolved. The potential of the cathode during deposition at a typical current density is also given. 

Electroplating is the electrolytic deposition of a thin film of metal on an object. The object to be electroplated (either metal or graphite-coated plastic) constitutes the cathode, and the electrolyte is an aqueous solution of a salt of the plating metal. Metal is deposited on the cathode by reduction of ions in the electrolyte solution. These cations are supplied either by the added salt or from oxidation of the anode, which is made of the plating metal (Fig. 12.16). 

The engineering firm insisted on heavily plated metal valves for DI water. They had never used plastic, which the laboratory operator had successfully employed in a previous installation. Management agreed with the engineers. The water was distributed to all sinks by standard PVC pipe, which worked very well after thorough flushing. 

Reactor type Single-channel thin-film micro reactor Bottom plate (metal block) material Nickel (or copper)... 

Bottom plate (metal Nickel (or copper) block) material Nickel tubing 500 pm 100 mm internal diameter length... 

This explains why it is possible to plate metals below hydrogen in the electrochemical series, from acid solutions, without hydrogen evolution, whereas care must be exercised in plating metals that are above hydrogen in the electrochemical series, from such solutions. 

The nickel-chromium plating process includes the steps in which a ferrous base material is electroplated with nickel and chromium. The electroplating operations for plating the two metals are basically oxidation-reduction reactions. Typically, the part to be plated is the cathode, and the plating metal is the anode. 

---