Magnesium-based

In the nuclear engineering field special magnesium-base alloys are extensively used as canning materials for uranium in gas-cooled reactors. 

The unequal attack which occurs in tap water, condensate and other mild electrolytes may lead to perforations of thin-gauge sheet and even to deep pitting of castings. In stronger electrolytes the effect is variable. In chloride solutions such as sea-water, attack on the metal usually results in the pitting of some areas only, but where the metal surface has been rendered reactive, as by shot blasting, attack may be so rapid that uniform dissolution over the whole surface may occur. In either case magnesium-base alloys are not usually suitable for use in aqueous liquids since they are not intrinsically resistant to these electrolytes. 

Fig. 4.17 Samples of high-purity AZ31 (upper photographs) and ZW3 (lower photographs) magnesium-base alloys, fitted with mild-steel nuts and bolts and exposed to a variety of corrosion conditions, (a) 4-S hours immersion in 37 salt soln., (b) 180 days immersion in distilled water, (c) 4 days immersion in borehole water, (d) 180 days in humidity cabinet sea-water spray and (e) 180 days atmospheric exposure...

The proneness or otherwise to corrosion is essentially the same in all the magnesium-base alloys and it is important to note that the requirements of protection therefore do not vary for the magnesium alloy under consideration. If conditions are such that any one of the alloys can be used satisfactorily without protection, then any other of the alloys can be so used. On the other hand, if a given protective scheme is found necessary for a particular alloy, then the same protective scheme will be found necessary (and will be equally effective) with any other magnesium-base alloy. 

Table 4.20 The more usual cleaning and chromating processes for magnesium-base alloys ...

Sodium cycle softening (base-exchange softening) is used primarily to remove the risk of calcium- and magnesium-based crystalline scale formation and deposition. The general reaction is as shown in Figure 9.2. 

Hot lay-up is most suited for standby and for short outages for minor repairs. Here, the metal surfaces are maintained at 170 °F (77 °C) or higher by an auxiliary heat source, such as a gas air heater, to deter moisture. Typically, magnesium-based treatments are employed at the rate of 1 lb per 1,000 lb/hr of steaming capacity to absorb and neutralize sulfuric acid vapor. These products are blown through the fireside using the FD fan. 

Cold lay-up is most suited for longer term idling and extended outage periods. Again, magnesium-based treatments are employed at rates similar to those used in fireside hot lay-up to absorb and neutralize sulfuric acid vapor. 

Magnesium-based additives are commonly employed to treat boiler furnace area fouling and corrosion conditions. They are injected into heavy fuel oil or other combustible material. Cerium is superior in action to magnesium salts, however, because an equivalent weight of cerium increases the melting point of the deposit more than that of magnesium. 

This lithium process is the analogue of the magnesium-based Barbier reaction [135],... 

F—Magnesium Magnesium anode Carbon, vanadium pentoxide, and magnesium chloride Magnesium-based thermal batteries... 

The magnesium-based pencil sharpner electrolytic cell used is shown in Fig. 15. It has the following features ... 

At lower pH, sulfur dioxide is mostly present and, as the pH increases from 4 to 9, the proportion of sulfite ion increases and that of the bisulfite ion decreases. Usually either calcium or magnesium bases are used to control the pH within the acidic range. The pH is dependent upon the relative solubility of the calcium or magnesium sulfite, and upon the excess of sulfur dioxide which is used. Because of the greater solubility of magnesium sulfite, the magnesium-based... 

Enantioselective conjugate addition [40] has become truly useful with the aid of dialkylzinc, cationic copper catalyst, and a chiral ligand (Eq. 1, see also Chapt. 7) [41]. Magnesium-based reagents have found use in quantitative fivefold arylation of Cgo (Eq. 10.2) [42] and threefold arylation of C70 [43], paving ways to new classes of cyclopentadienyl and indenyl ligands with unusual chemical properties. 

Y. Kojima, Y. Kawai, T. Haga, Magnesium-based nano-composite materials for hydrogen storage, J. Alloys Compd. 424 (2006) 294-298. 

Z. Dehouche, R. Djaozandry, 1. Huot, S. Body, 1. Goyette, T.K. Bose, R. Schulz, Influence of cycling on the thermodynamic and structure properties of nanocrystalhne magnesium based hydride, J. Alloys Compd. 305 (2000) 264-271. 

M. Au, Hydrogen storage properties of magnesium based nanostructured/amorphous composite materials, Mater. Res. Soc. Symp. Proc. 801 (2004) BBl.5.1-1.5.14. 

K Yvon, B. BertheviUe, Magnesium based ternary metal hydrides containing alkali and alkaline-earth elements, J. Alloys Compd. 425 (2006) 101-108. 

Parameter Ammonia base mill Sodium base mill Magnesium base mill Calcium base mill ... 

Drugs that may affect tipranavir include aluminum- and magnesium-based antacids, azole antifungals, clarithromycin, efavirenz, loperamide, NRTIs (ie, didanosine, zidovudine), rifamycins (rifampin), St. John s wort, tenofovir. 

Magnesium-based materials are used as the pick-up agent in currently available additives. In the FCC regenerator, the additive reacts with SO3 to form magnesium sulfate ... 

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