Describes all aspects of electroplating. A user friendly manual. The most comprehensive manual available. Please see Table of Contents.Table of Contents abrasives acid dipping activated carbon activation adhesion of deposits agitation alkaline cleaning alloy plating aluminum, coloring of aluminum, plating on analysis of plating solutions anodes anodizing of aluminum antimony plating antique finishes arsenic alloy plating arsenic plating atoms;atomic structure barrel finishing barrel plating bent cathode test beryllium plating bismuth plating black alloy plating black coatings black nickel plating blast cleaning blue finishes brass, coloring of brass leaded, plating on brass plating bright dipping brighteners;bright plating bronze, coloring of bronze, leaded, plating on bronze, plating on bronze finishes(bronzing) bronze plating buffing burnishing; burring burnt deposits; burning busbars cadmium dipping cadmium plating cast iron, plating on cathode efficiency cathodes ceramics, plating on chemical coloring chemical plating(electroless) chemical polishing chromate coatings chromium plating cleaning cobalt plating coloring of metals conversion coatings copper alloy plating copper,copper alloys, plating on copper, coloring of coppering copper plating corrodkote test corrosion;corrosion tests current density degreasing displacement plating drag-out dummying(electrolytic purification) electroforming electroless plating electrolytic purification electrons electropolishing filtration gallium plating galvanic displacement plating galvanic series generators germanium plating guilding glass, plating on gold alloy plating gold finishes gold plating granite finish green finishes grinding gun metal finish hardness hull cell immersion plating nickel plating niobium plating nonconductors, plating on osmium plating oxidized finishes palladium plating passivity periodic reverse plating pewter, plating on pH phosphate coatings pickling plaster, plating on platinum plating polarization polishing power supplies prep. of metals for plating quartz, plating on racks rectifiers rhenium plating rhodium plating rinsing selenium plating silvering silver plating stainless steel, plating on steel,plating on strike cleaning striking stripping tantalum plating tellurium plaitng testing of electrodeposits thallium plating theory of plating tin plating titanium plating tumbling tungsten plating uranium plating vanadium plating ventilation waste disposal zinc base die castings zinc plating zirconium plating
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NICKEL PLATING See stripping
Nickel is normally plated from an acid solution, containing nickel sulfate and nickel chloride. Special-purpose baths also exist for plating hard nickel, plating nickel at very high speeds plating nickel directly on zinc, and for barrel-plating nickel. Most of these are variations on the sulfate-chloride acid nickel bath. Since nickel is a relatively active metal in the plating sense. it is not usually necessary to nickel-strike work before nickel plating in order to avoid galvanic displacement films. Only zinc, aluminum, and magnesium will readily form displacement nickel coatings. When nickel-plating these metals, however, it is more conventional to employ a nickel-plating solution especially designed for the purpose than to use a strike. There are some applications, however, for nickel strikes. When gold, silver, or rhodium is plated on low- or high carbon steel, cast iron, or copper and its alloys, it is customary to employ an intermediate nickel strike. The most important application of nickel strikes, however, is the activation of passive alloys of nickel or stainless steel, prior to electroplating.
NICKEL STRIKE Plating on stainless steel, nickel and nickel alloys requires that the basis metal be given an activating treatment before electroplating to avoid blistering and peeling. The recommended treatment is to etch anodically and then to strike the stainless-steel parts in a Wood's nickel-strike solution. The work should be cleaned in the normal manner, rinsed, and etched in the strike bath for 1/2 to 1 min by making the work anodic at 15 to 20 asf. Then the polarity is reversed, the work being made cathodic, with nickel striking taking place at 15 to 20 asf for 1 min, or until a continuous nickel plate is obtained. Either the tank or the rheostat should be equipped with a double-pole, double-throw switch for current reversal. The formula for the Wood's nickel bath is given in Table 1.
WATTS NICKEL PLATING Nickel is widely plated commercially. The most common application is the production of a decorative and corrosionresistant finish, which is usually chromium-plated subsequently to prevent tarnishing. Such finishes require a bright nickelplated surface. This is accomplished either by plating, a dull white nickel from a Watts (sulfate-chloride) bath and buffing; or by plating a semibright, buffable nickel from a modified Watts bath and buffing; or by plating a fully bright nickel from proprietary solutions. The proprietary solutions are Watts-type baths, to which are added organic addition agents that are designed to impart brightness and/or leveling characteristics to the deposit. Proprietary solutions will not be discussed here, as the methods of operation are best obtained from the vendor. However, most of the principles that apply to Watts nickel-plating solutions apply to bright solutions as well. In addition to decorative applications, thick nickel coatings are useful for industrial applications such as the building up of worn parts, electroforming, and the like, where nickel offers the advantage, of hardness coupled with good corrosion resistance. Nickel plating has been used quite extensively by chemical plants in producing valves with good corrosion characteristics. Such industrial deposits are generally 0.005 to 0.010 in. thick. Nickel is extensively used in electroforming in order to produce many types of molds for plastics, phonograph-record masters, stamping plates, and electrotypes.
Equipment Tanks It is an established practice to use steel tanks lined with a suitable rubber or synthetic coating. For proprietary bright nickel baths, it is advisable to check with the firm marketing the solution to determine what rubber linings are compatible with their addition agents. The complexity of the tank design (see Fig. 5) is dependent, to a great degree, on the type of deposit required and the particular production needs. In a high-production shop where high-quality deposits are essential, it is recommended that the tank be equipped so that it can be continuously dummied, heated externally, and filtered continuously. The heat exchangers and filters should have separate pumps and piping systems to circulate the solution for temperature control. The treatment tank should have a large enough capacity so that the nickel solution can be transferred to it for treatment as required. This steel tank should be lined with rubber. It is good practice to plate the anode and cathode rods with a good deposit of nickel in order to prevent copper contamination from that source. All tanks should be set on glass bricks or should be otherwise insulated electrically from any piers of building brick which may be used to support the tank. In the past, much nickel plating was done from steel or wood tanks with a chemical lead lining. Such tanks had many shortcomings, such as bipolar action of the plating current, and limitation of the chloride content of the nickel solution equal to 4 1/2 oz/gal of nickel chloride to avoid lead contamination. Gradually, these tanks have been replaced by rubberlined tanks. Before the use of lead-lined tanks, many plating shops employed pitch-lined wooden plating tanks when the nickel solutions were used at room temperature. These tanks had definite temperature limitations, however, and so their use declined with the advent of warm nickel baths. Auxiliary equipment The pumps and piping between the heat exchanger and the plating tank generally suffice for solution agitation. In smaller installations, the filter and heat exchanger are sometimes connected in series. The heat exchanger then follows the filter, both utilizing one pump.
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