Alloy anodes

Wrought lead—calcium—tin anodes have replaced many cast lead—calcium anodes (14). Superior mechanical properties, uniform grain stmcture, low corrosion rates, and lack of casting defects result in increased life for wrought lead—calcium—tin anodes compared to other lead alloy anodes. 

Silver reduces the oxygen evolution potential at the anode, which reduces the rate of corrosion and decreases lead contamination of the cathode. Lead—antimony—silver alloy anodes are used for the production of thin copper foil for use in electronics. Lead—silver (2 wt %), lead—silver (1 wt %)—tin (1 wt %), and lead—antimony (6 wt %)—silver (1—2 wt %) alloys ate used as anodes in cathodic protection of steel pipes and stmctures in fresh, brackish, or seawater. The lead dioxide layer is not only conductive, but also resists decomposition in chloride environments. Silver-free alloys rapidly become passivated and scale badly in seawater. Silver is also added to the positive grids of lead—acid batteries in small amounts (0.005—0.05 wt %) to reduce the rate of corrosion. 

Magnesium Alloys, Anodic Treatment Of, MUitary Specification MIL-M-45202, Dept, of the Army, Army Materials and Mechanics Research Center, Watertown, Mass., Oct. 3, 1968. 

The electrolysis is conducted at 90—95°C and an anode current density of about 50 120 A/m when using lead alloy anodes and lead cathodes. Using graphite electrodes, the current density is from 70 100 A/m using titanium anodes and graphite cathodes, the current density is 50 80 A/m (82). 

Finally it must be remembered with these anodes that Pb02 film, which acts to provide the current leakage, can be detached even when no current is flowing. With renewed anodic loading, the film has to be reformed, which leads to a corresponding consumption of anode material. The anodes should therefore be operated as continuously as possible with a basic load. An exhaustive treatment of the composition and behavior of lead alloy anodes can be found in Ref. 13. 

Mine, F., Ogaia, Y., Yasuda, M. Consumption of Lead-silver Alloy Anodes in Sulfuric Acid, B. Electrochem., 4, 61-65 (1988)... 

Barnard, K. N., Christie, G. L. and Gage, D. G. Service Experience with Lead Silver Alloy Anodes in Cathodic Protection of Ships , Corrosion, 15, 11, 581-586 (1959) Peplow, D. B. and Shreir, L. L. Lead/Platinum Electrodes for Marine Applications , Corr. Tech. Apr. (1984)... 

Morgan, J. FI. Lead Alloy Anode for Cathodic Protection , Corr. Tech. 10/12. 348-352 (1958)... 

Anode efficiency is of little practical significance and can be misleading. For example, magnesium alloy anodes often have an efficiency ca. 50% whilst for zinc alloys the value exceeds 90% it does not follow that zinc alloy anodes are superior to those based on magnesium. Efficiency will be encountered in many texts on sacrificial anode cathodic protection. 

Alloy Anode potential (V vs. Ag/AgCl/Seawatcr) Max current capacity (Ah/kg)... 

Aluminium alloy anodes based on Zn-Al-In and Zn-Al-Hg have now become the work-horse materials for seawater service. 

Combined Alloy Anodes for Repid Structure Polerisetion... 

There are obviously situations which demand considerable over-design of a cathodic protection system, in particular where regular and efficient maintenance of anodes is not practical, or where temporary failure of the system could cause costly damage to plant or product. Furthermore, contamination of potable waters by chromium-containing or lead-based alloy anodes must lead to the choice of the more expensive, but more inert, precious metal-coated anodes. The choice of material is then not unusual in being one of economics coupled with practicability. 

A comparison of typical properties of cathodic protection materials is given in Table 10.23, but is by no means comprehensive. It is obvious that the modification of an alloy, environment or other important factors will be reflected in the life and output characteristics. In some cases the maximum voltages and current densities recommended can be vastly exceeded. In others, particularly where abnormal levels of environmental dissolved solids are met, factors of safety should be applied to modify the proposed figures. Acceptance of a much reduced or uncertain life, weighed against a possible economy, may also influence the chosen working limits. For example, the life of ferrous alloy anodes may, in practice, be only two-thirds of that expected because of preferential attack eventually leading to disconnection of all or part of the anode from the source of e.m.f. 

For the more complex alloys anodic polarisation offers a vital extra variable in the use of selective etchants and has been widely exploited for alloys for which simple chemical etchants have proved inadequate. Besides many types of alloys steelthis technique has been applied to copper and the Cu-Be-Ni-Zr alloys " , uranium-base alloys " , Ni-Al alloys , tin-bearing invar and many others. 

Cyanide solutions are used almost exclusively. One typical solution contains copper cyanide 26 g/1, zinc cyanide 11 g/1, sodium cyanide (total) 45 g/1 and sodium cyanide ( free ) 7 g/l This bath is operated at pH 10.3-11.0, 110 A/m and 27-35 C, with 75 Cu-25 Zn alloy anodes. Many other solutions are used including a special rubber-bonding bath and a high-speed bath which is capable of being used at up to 16 A/dm . ... 

The alternative alloy anodes which exhibit good cycle life in coin cells (Table 1) are not applied to cylindrical cells. This is because they are brittle and these alloy anodes turn into fine particles after cycling when the anode is spirally wound in the... 

It is now well established that in lithium batteries (including lithium-ion batteries) containing either liquid or polymer electrolytes, the anode is always covered by a passivating layer called the SEI. However, the chemical and electrochemical formation reactions and properties of this layer are as yet not well understood. In this section we discuss the electrode surface and SEI characterizations, film formation reactions (chemical and electrochemical), and other phenomena taking place at the lithium or lithium-alloy anode, and at the Li. C6 anode/electrolyte interface in both liquid and polymer-electrolyte batteries. We focus on the lithium anode but the theoretical considerations are common to all alkali-metal anodes. We address also the initial electrochemical formation steps of the SEI, the role of the solvated-electron rate constant in the selection of SEI-building materials (precursors), and the correlation between SEI properties and battery quality and performance. 

Besides using Pt-Ru or Pt-Co alloy anodes, CO poisoning can be mitigated by elevating the operating temperature. However, temperature dependencies of the HOR rates in the presence of CO with relevance to PEFC operation have been scarcely reported. One of the difficulties is correction of the change in H2 concentration [H2] in the... 

Zinc electrowinning takes place in an electrolytic cell and involves running an electric current from a lead-silver alloy anode through the aqueous zinc solution. This process charges the suspended zinc and forces it to deposit onto an aluminum cathode (a plate with an opposite charge) that is immersed in the solution. Every 24 to 48 h, each cell is shut down, the zinc-coated cathodes removed and rinsed, and the zinc mechanically stripped from the aluminum plates. The zinc concentrate is then melted and cast into ingots, and is often as high as 99.995% pure. 

Zinc electrowinning Zinc in a sulfuric acid/ aqueous solution, lead-silver alloy anodes, aluminum cathodes, barium carbonate, or strontium, colloidal additives... 

Doped Nickel Cathode Alloy Anode Low Cost... 

Yang J., Winter M., Besenhard JO. Small particle size multiphase Li-alloy anodes for lithium-ion batteries. Solid State Ionics 1996 90 281-87. 

The original process used aqueous tetraethylammonium ethylsulfate as the electrolyte, a lead cathode, and a lead-silver alloy anode. The Mark II process, commercialized in the mid-1970s, uses an emulsion of acrylonitrile in aqueous sodium phosphate containing a salt of the hexamethylene-bis-(ethyldibutylammonium) cation. The process was invented in 1959 by M. M. Baizer at Monsanto Corporation, St. Louis, MO. It was commercialized in 1965 and has been continuously improved ever since. The process is also operated in Japan by Asahi Chemical Industry Company. In 1990, the world production of adiponitrile by this process was over 200,000 tonnes per year. 

Lead-antimony-silver alloy anodes, 74 777 Lead-antimony-tin alloys, 74 771-772 Lead-antimony-tin white bearing alloys, 3 52... 

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