Corrosion electrolyte

The Electrolytic Corrosion Test. Also developed for use on nickel—chromium and copper—nickel—chromium decorative automobile parts is the electrolytic corrosion (EC) test (44). Plated specimens or parts are made anodic in a corrosive electrolyte under controlled conditions for 2 min, and then tested for penetration to the substrate. 

In general it is wise to avoid as far as possible, the use of incompatible metallic joints in marine and offshore practice, since these are often in contact with seawater or water that contains chlorides which are effective corrosive electrolytes. It is prudent to take very considerable precautions to prevent corrosion at the design and installational stages. However, the widely diverse properties required of the materials used in such installations make it impracticable to avoid all such joints. 

Paint for structural steelwork is required mainly to prevent corrosion in the presence of moisture. In an industrial atmosphere this moisture may carry acids and in a marine atmosphere this moisture may carry chlorides. Paint is therefore required to prevent contact between steel and corrosive electrolytes, and to stifle corrosion, should it arise as a result of mechanical damage or breakdown of the coating through age and exposure. 

The primary disadvantage of current MCFC technology is durability. The high temperatures at which these cells operate and the corrosive electrolyte used accelerate component breakdown and corrosion, decreasing cell life. Scientists are currently exploring corrosion-resistant materials for components as well as fuel cell designs that increase cell life without decreasing performance. 

CO sensor allows detection of CO in the presence of hydrocarbons and other adsorbable contaminants. The membrane Is usually chosen for Its ability to protect the sensing electrode. However, If It has low permeability to air, the sensor will have a slower response time. The electrolyte and counter electrode have also been reported as Influencing selectivity and device performance In the determination of hydrazines (5) and NO2 (9), respectively. Finally, materials of construction are typically Teflon and high-density plastics like polypropylene because such materials must be compatible with reactive gases and corrosive electrolytes. 

The electrons pumped into the corrodible metal have come, in the above method, from the dissolution of a scarificial auxiliary metal. Instead, they can come from an external current source (i.e., an electrical power supply). The electrical circuit, however, has to be completed, and toward this end, an auxiliary inert electrode can be immersed in the corrosive electrolyte to provide a return path for the electron current (Fig. 12.38). The external source can then be adjusted so that the potential difference between the corrodible metal and its environment becomes negative with respect to its equilibrium potential. Under these circumstances, the whole of the metal to be protected against corrosion will function as an electron source for the electronation reaction, and the second electrode will serve as an electron sink for some deelectronation reaction (Hoar). 

The zinc silicate film is porous and readily absorbs corrosive electrolyte. The film is harder, stronger than organic zinc-rich films. These films have better resistance to solvent and heat than the organic zinc-rich primers and may be used for tank linings and other applications up to 400°C. 

Flade potential electrode potential F of a metal in contact with a corrosive electrolyte solution where the current associated with the anodic metal dissolution (- corrosion, active region) drops to very small values. See also - Flade, and -> passivation. 

Massive electrochemical attack known as galvanic corrosion [58,59] is the most severe form of copper corrosion. It can completely remove the copper from the structures (Figs. 17.25 and 17.26). It can occur when the wafers are exposed to a corrosive electrolyte for an extended period. It can also occur if the slurry does not contain enough or effective corrosion inhibitor. The source of such a galvanic potential on the patterned copper surface may be due to the fact that some copper structures connected to transistors have a different electrical potential than the rest of the wafer surface. Another possible cause of this type of galvanic potential is related to the barrier material induced metal metal battery effect. Most copper CMP slurries have been developed for Cu structures with Ta or TaN as a barrier material. In some cases, other metals may also be used in addition to the barrier metal. For example, a metal hard mask could contribute to the galvanic corrosion effects. It is also possible that some types of copper are more susceptible to corrosion that others. The grain... 

Molten carbonate fuel cells (MCFCs) use an electrolyte composed of a molten carbonate salt mixture suspended in a porous, chemically inert ceramic lithium aluminum oxide (I.iAIO,) matrix. MCFCs are large and operate at very high temperatures (1,200°F). Because they use a corrosive electrolyte, their durability is limited. 

Safety issues have also become more important in recent years as more active battery chemistries have been developed. In particular, the presence of corrosive electrolytes and highly ignitable or explosive battery materials under certain conditions has become an issue which the battery industry must address. At present, it appears as if improvement in the recycling rates of spent batteries will produce the most substantial decreases in the environmental and human health impacts of battery systems. 

C ambient pressure 77 - 80 1.84 - 2.25 1.3 - 2.5 4.3 - 4.9 Commercial large-scale units proven technology, simple, low efficiency, corrosive electrolyte... 

High- temperature (solid Y2O3 stab. Z1O2) (A) Ni-NiO (C) Ni 800 - 1000 °C < 3 MPa 90 - 100 0.95 - 1.3 3 - 10 3.5 very small lab scale units, non-corrosive electrolyte, severe materials and fabrication problem... 

Pt catalyst ripening, electrocatalyst loss or re-distribution, carbon corrosion, electrolyte and interfacial degradation... 

Metals and alloys used in engineering are usually in their passive state. When a passive metal in presence of a corrosive electrolyte rubs against a solid, both corrosion and wear occur, but because the mechanical and electrochemical mechanisms interact with each other, the overall rate of material loss is not just the sum of material lost by corrosion and by wear taken individually. 

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