Corrosion resistance mechanism

In general, the requirements for plate and plate materials listed in Table 5.1 can be classified as electrical properties, corrosion resistance, mechanical properties, gas permeability or soundness, weight, and cost. Although the output power of a stack is determined by many factors, one simple interpretation of the 2010 DoE cost target is US 2 per plate, which has often been quoted as a convenient estimation [8]. In addition to the cost requirements, the other requirements are all linked either directly or indirectly to the functions of the plate mentioned earlier. 

Slowly add 50 mL of concentrated NH OH 56% (=28% NHj), meanwhile rapidly stirring the solution with a corrosion resistant mechanical paddle. The Fe O cores produced in this way are not stabilized and sink as a heavy, black precipitate. 

Okazaki, Y, Rao, S., Ito, Y, and Tateishi, T. Corrosion resistance, mechanical properties, corrosion fatigue strength and cytocompatibUity of new Ti alloys without Al and V. Biomaterials, 19,1197-1215 (1998). 

Odashima, H., et al. (1992). Corrosion resistance mechanism of a newly developed organic composite coated sheet steel for automotive use. Galvatech 92, Verlag Stahleisen, Diisseldorf, Germany, pp. 377-382. 

Improvements in corrosion resistance, mechanical properties and weldability of duplex austenitic/ferritic steels Werkst. Korros. 34 (1983) 1, p. 27-31... 

E-CR boron-free good acid corrosion resistance mechanical properties similar to E-glass... 

Wong KKY, Tan LUL, Saddler JN (1988) Multiplicity of p-l,4-xylanase in microorganisms function and applications. Microbiol Rev 52 305-317 Wu Y-S, Wang C-S, Fan C-Z, Wang S-J, Li Z-C (1992) A study on corrosion-resistance mechanism of the ancient mirror Hei Qi Gu . Acta Phys Sinica... 

The advantages of a plastic intercooler include the following corrosion resistance mechanical robustness (no fatigue failures) lighter weight and potential for lower cost. Metal intercoolers today are primarily aluminum alloys which contain special alloy to support the brazing process used in manufacture. Thin-walled metal alloys have potential to corrode very quickly and aluminum alloys suffer from a finite fatigue fife. Most plastics do not corrode when exposed to the normal automotive environment salt water, antifreeze and lubricants. 

For example,copper has relatively good corrosion resistance under non-oxidizing conditions. It can be alloyed with zinc to yield a stronger material (brass), but with lowered corrosion resistance. Flowever, by alloying copper with a passivating metal such as nickel, both mechanical and corrosion properties are improved. Another important alloy is steel, which is an alloy between iron (>50%) and other alloying elements such as carbon. 

Because the element not only has a good absorption cross section for thermal neutrons (almost 600 times that of zirconium), but also excellent mechanical properties and is extremely corrosion-resistant, hafnium is used for reactor control rods. Such rods are used in nuclear submarines. 

The industrial value of furfuryl alcohol is a consequence of its low viscosity, high reactivity, and the outstanding chemical, mechanical, and thermal properties of its polymers, corrosion resistance, nonburning, low smoke emission, and exceUent char formation. The reactivity profile of furfuryl alcohol and resins is such that final curing can take place at ambient temperature with strong acids or at elevated temperature with latent acids. Major markets for furfuryl alcohol resins include the production of cores and molds for casting metals, corrosion-resistant fiber-reinforced plastics (FRPs), binders for refractories and corrosion-resistant cements and mortars. 

SiHcon nitride (see Nitrides) is a key material for stmctural ceramic appHcations in environments of high mechanical and thermal stress such as in vehicular propulsion engines. Properties which make this material uniquely suitable are high mechanical strength at room and elevated temperatures, good oxidation and creep resistance at high temperatures, high thermal shock resistance, exceUent abrasion and corrosion resistance, low density, and, consequently, a low moment of inertia. Additionally, siHcon nitride is made from abundant raw materials. 

As a tme thermoplastic, FEP copolymer can be melt-processed by extmsion and compression, injection, and blow molding. Films can be heat-bonded and sealed, vacuum-formed, and laminated to various substrates. Chemical inertness and corrosion resistance make FEP highly suitable for chemical services its dielectric and insulating properties favor it for electrical and electronic service and its low frictional properties, mechanical toughness, thermal stabiUty, and nonstick quaUty make it highly suitable for bearings and seals, high temperature components, and nonstick surfaces. 

Rea.ctivity ofLea.d—Ca.lcium Alloys. Precise control of the calcium content is required to control the grain stmcture, corrosion resistance, and mechanical properties of lead—calcium alloys. Calcium reacts readily with air and other elements such as antimony, arsenic, and sulfur to produce oxides or intermetaUic compounds (see Calciumand calciumalloys). In these reactions, calcium is lost and suspended soHds reduce fluidity and castibiUty. The very thin grids that are required for automotive batteries are difficult to cast from lead—calcium alloys. 

Lead—copper alloys are specified because of superior mechanical properties, creep resistance, corrosion resistance, and high temperature stabiUty compared to pure lead. The mechanical properties of lead—copper alloys are compared to pure lead, and to lead—antimony and lead—calcium alloys in Tables 4 and 5. 

Copper and nickel can be alloyed with zinc to form nickel silvers. Nickel silvers are ductile, easily formed and machined, have good corrosion resistance, can be worked to provide a range of mechanical properties, and have an attractive white color. These alloys are used for ornamental purposes, as sHverplated and uncoated tableware and flatware in the electrical iadustry as contacts, connections, and springs and as many formed and machined parts (see Electrical connectors). 

Niobium is also important in nonferrous metallurgy. Addition of niobium to tirconium reduces the corrosion resistance somewhat but increases the mechanical strength. Because niobium has a low thermal-neutron cross section, it can be alloyed with tirconium for use in the cladding of nuclear fuel rods. A Zr—l%Nb [11107-78-1] alloy has been used as primary cladding in the countries of the former USSR and in Canada. A Zr—2.5 wt % Nb alloy has been used to replace Zircaloy-2 as the cladding in Candu-PHW (pressurized hot water) reactors and has resulted in a 20% reduction in wall thickness of cladding (63) (see Nuclear reactors). 

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