Electrolytic nickel coating, applications

Watts bath — The Watts bath is the classical electrolyte for the -> electrodeposition of functional nickel coatings. It contains nickel sulfate (240-450 gL-1 of the hexahy-drate), nickel chloride (45-90 gL-1 of the hexahydrate), and boric acid (30-50 g L-1) and is usually operated between pH 2 and 4.5 and at 40-70 °C. The chloride content of the bath is crucial to ensure the dissolution of the nickel anode. In combination with - leveling agents and brighteners the Watts bath is also used for decorative nickel coatings. Its applicability for -> electroforming is limited due to tensile stresses in the deposits. 

Nickel-terne-coated steel includes an electrolytic flash coating of nickel (1-1.5 g/m ) underneath a conventional lead-tin coating for enhanced corrosion resistance. Applications are similar to the conventional lead-tin alloy coatings described previously. 

Rote et al. (1993, 1994) used a carotid thrombosis model in dogs. A calibrated electromagnetic flow meter was placed on each common carotid artery proximal to both the point of insertion of an intravascular electrode and a mechanical constrictor. The external constrictor was adjusted with a screw until the pulsatile flow pattern decreased by 25 % without altering the mean blood flow. Electrolytic injury to the intimal surface was accomplished with the use of an intravascular electrode composed of a Teflon-insulated silver-coated copper wire connected to the positive pole of a 9-V nickel-cadmium battery in series with a 250000 ohm variable resistor. The cathode was connected to a subcutaneous site. Injury was initiated in the right carotid artery by application of a 150 xA continuous pulse anodal direct current to the intimal surface of the vessel for a maximum duration of 3 h or for 30 min beyond the time of complete vessel occlusion as determined by the blood flow recording. Upon completion of the study on the right carotid, the procedure for induction of vessel wall injury was repeated on the left carotid artery after administration of the test drug. 

For the electrochemical plating of silver, a 99.9% silver anode is used with an electrolyte composed of [Ag(CN)2] and other required additives. Silver should not come into direct contact with steel or severe corrosion can occur. Steel parts can be protected by first coating with copper or nickel. Silver coating is commonly used for flatware, hol-loware, jewelry, electrical, and mechanical applications. Chemical methods are available to apply silver as a coating to plastic or glass. 

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