Additives electroplating baths

Quaternary Salts. Herbicides paraquat (20) and diquat (59) are the quaternary salts of 4,4 -bipyridine (19) and 2,2 -bipyridine with methyl chloride and 1,2-dibromoethane, respectively. Higher alkylpyridinium salts are used in the textile industry as dye ancillaries and spin bath additives. The higher alkylpyridinium salt, hexadecylpytidinium chloride [123-03-5] (67) (cetylpyridinium chloride) is a topical antiseptic. Amprolium (62), a quaternary salt of a-picohne (2), is a coccidiostat. Bisaryl salts of butylpyridinium bromide (or its lower 1-alkyl homologues) with aluminum chloride have been used as battery electrolytes (84), in aluminum electroplating baths (85), as Friedel-Crafts catalysts (86), and for the formylation of toluene by carbon monoxide (87) (see QuaternaryAA ONiUM compounds). 

The simplest electroplating baths consist of a solution of a soluble metal salt. Electrons ate suppHed to the conductive metal surface, where electron transfer to and reduction of the dissolved metal ions occur. Such simple electroplating baths ate rarely satisfactory, and additives ate requited to control conductivity, pH, crystal stmcture, throwing power, and other conditions. 

Cadmium oxide is used in storage battery electrodes. Its solution, mixed with sodium cyanide, is used in electroplating baths. Other uses are in PVC heat stabilizers as an additive to nitrile rubbers and plastics to improve heat resistance and in ceramic glazes and phosphors. 

Cobalt(II) sulfate is used in storage batteries and electroplating baths for cobalt. It also is used as a dryer for lithographic inks in pigments for decorating porcelains in ceramics, glazes and enamels to protect from discoloring and as a additive to soils. 

Anodes. There are two types of anodes soluble and insoluble. Most electroplating baths use one or the other specifically however, a few baths use either or both. Chromic acid plating baths use insoluble anodes alkaline zinc cyanide baths use both noncyanide alkaline zincs may use either. Soluble anodes are designed to dissolve efficiendy with current flow and preferably, not to dissolve when the system is idle. A plating solution having the anode efficiency close to the cathode efficiency provides a balanced process that has fewer control problems and is less cosdy. If the anode efficiency is much greater than the cathode efficiency and there are only small solution losses, the dissolved metal concentration rises until at some time the bath has to be diluted back or the excess metal has to be reduced by some other means. If the anode efficiency is less than the cathode efficiency, the dissolved metal decreases, pH decreases, and eventually metal salt additions and other solution corrections are required. Based on the cost of metal, it is usually considerably more economical to plate from the anode rather than add metal salt. Copper cyanide, for example, costs about twice as much to add than to dissolve a comparable amount of copper anode. Additionally, the anion added with the metal salt may build up in the plating solution. 

In Section 4.4, finally, troublesome aspects are shortly summarized. An important aspect is that the electrochemical window alone is not sufficient and one can be pretty surprised if the electroreduction of e.g. TaCls rather delivers non-stoichiometric halides instead of the desired tantalum metal. For an electroplating bath the solution chemistry also plays an important role and a new concept of additives seems to be necessary. 

Use Preparation of cadmium sulfide, analytical chemistry, photography, dyeing and calico printing, ingredient of electroplating baths, addition to tinning solution, manufacture of special mirrors, manufacture of cadmium yellow. 

Use Catalyst for rapid biochemical assimilation of iron, electroplating baths, photometric analysis, feed additive. 

Cetylpyridinium is a popular electrolyte solution additive in electroplating baths. 

Uses Corrosion inhibitor in oil well acidizing, mild steel pickling, mild steel cleaning in acid systems electroplating bath additive curative for paints, elastomers, adhesives Manuf/Distrib. Air Prods. 

Synonyms 1 -(3-Sulfoprop-1 -yl)-2-vinylpyridinium betaine Uses Functional monomer for hydrogels, antistatics, adhesives, emulsions, paints and inks additive for electroplating baths Manuf./Distrib. ABCR Trade Names SPV... 

Classification Nonaromatic sulfur-oxygen compd. Empirical C4H10N2O3S2 Properties M.w. 198.26 m.p. 254-256 C Toxicology Irritating to eyes, skin, respiratory system TSCA listed Uses Reactive sulfonate additive for electroplating baths... 

Uses Reactive functional thioether additive for electroplating baths... 

Uses Surfactant, solubilizer, foaming agent, antistat, bactericide for detergents, textiles, cosmetics electroplating bath additive Trade Name Synonyms Ralufon DCH [Raschig Raschig AG http //www.raschig.de]... 

---