Aluminium content

The impurities likely to be present in nominally pure tin are unlikely to affect its corrosion resistance, except for minor effects on the rate of oxidation in air. Small aluminium contents, however, may result in a severely embrittling intercrystalline attack by water. The addition of antimony counteracts this effect. Although 0-1% magnesium appears to be tolerable, larger amounts produce effects similar to those of aluminium. 

The physical properties of the newer alloys have been well documented (see bibliography). Essentially, they lie between those of Alloy 5 (Alloy B) and of Alzen 305 in Table 4.31, broadly in relation to their aluminium content. The mechanical properties vary considerably according to the method... 

Table 7.18 shows that the rate constants at 928°C for the Hastelloy alloys are considerably higher than those for molybdenum-free compositions, although the very low chromium content of Hastelloy W is doubtless a significant factor in this connection. It is noteworthy that the molybdenum-containing low-chromium alloy listed in Table 7.19 is generally superior to the others but this high resistance to oxidation is associated with its relatively high aluminium content. 

Aluminium content m Meta loss (mm/y) Total penetration (mm/y)... 

Intermediate alloy compositions include a zinc-15%-aluminium alloy for metal spraying (higher aluminium contents are unsuitable for spraying wire) and a zinc-30%-aluminium-0.2%-magnesium-0.2%-silicon coating (Lavegal) for sheet. 

We alluded earlier to the variety of structural modifications which may he observed in sheet silicates. Clearly it is a matter of considerable in jortance to he able to determine if, for example, the aluminium content within a clay arises p a ely from octahedral substitution (as in montmorillonite) or whether there is some tetrahedral component (as in heidellite). a1 MASNMR readily provides the necessary answers. Figvire 1 illustrates the a1 spectrum for a synthetic heidellite material with Na as charge balancing cation. Aluminium in two distinct chemical environments is observed, with chemical shifts corresponding to octahedrally and tetrahedrally co-ordinated aluminium. 

Increase in concentration of aluminium and phosphoric acid in the liquid serves to slow the reaction. This observation is in line with the above reaction scheme. Increase in the aluminium content will serve to increase the thickness of the coating formed around zinc oxide particles. Increase in phosphoric acid content implies a decrease in water content and an impairment of the hydration reaction. 

Ashton and Chan [ 1 ] have reviewed the techniques for the collection of seawater samples preservation, storage, and prevention of contamination are all discussed. The most appropriate measurement techniques, preconcentration and extraction, method validation, and analytical control are all covered. The apparent aluminium content of seawater stored in ordinary containers such as glass and polyethylene bottles decreases gradually, e.g., to half in 2.5 h. But if the samples are acidified with 0.5ml/l concentrated sulfuric acid the aluminium content remains constant for at least one month. Accordingly, samples should be acidified immediately after collection. However, the aluminium could be recovered by acidifying the stored samples and leaving them for at least five hours. 

The protons released are presumably available to compensate for the loss of the charge balancing cations within the zeolite. In conventional syntheses, the phtha-lonitrile condensation normally requires the nucleophilic attack of a strong base on the phthalonitrile cyano group [176, 177]. This function is presumably accommodated by the Si-O-Al (cation) basic sites within the ion-exchanged faujasite zeolites [178, 179]. The importance of this role is perhaps emphasized by the widespread use of alkali metal exchanged faujasites, particularly the more basic NaX materials of higher aluminium content [180, 181] as hosts for encapsulated phthalocyanine complexes. 

The aluminium content of the two samples is comparable, when referred to the silica content of the original clay, and the two PILC have comparable surface areas after calcination at 300°C. The ACH bentonite was formed into small extrudates and flash-dried, whereas sample G5 was dried in a thin cake. In both cases, crushing to a fine powder was easy. Sample G5 retains a higher surface area at 800°C in spite of a higher potassium content. Therefore the K O content of the PILC is not the predominant factor for the thermal stability. 

Calcination temperature up to which catalytic activity remains constant. 6 Calcination temperature at which catalytic activity falls to zero. c Aluminium content 47.5 atoms/unit cell (dealuminated). 

Given in Table 4.4.1 are typical results of high aluminium content refractories (80% A1203) at three temperature levels. 

The nickel and aluminium contents of the catalysts were determined by atomic absorption spectroscopy [AAS). Tin and chlorine contents of the modified catalysts given in Table 2 were determined by AAS and chemical analysis, respectively. 

On zeolites, coke is built by a mechanism initiated on acid sites, and the extent of this deposit is often correlated with the A1 content of the solid. In odCB conversion the stability of the catalyst, expressed as the kd constant, does not appear directly correlated with the aluminium content of the solid. Actually, for that reaction, tarry materials are formed both by... 

The aluminium content is commonly used as an indicator of the granulometry of the sample, since most of it is involved in the alumino-silicates which are well known to be the most important part of the smaller fraction. A rather good correlation (Fig. 9) can be found between S.S.A. and A1 content. 

Reactions of cyclo-olefins within the zeolites can generate aromatics by bi-molecular hydrogen transfer reactions. Such reactions are expected to be more favourable with REHY because of its greater framework aluminium content and because of restricted access to the inter-crystalline pores in ZSM-5. This is... 

Bertea et /.173-751 reported the vapour phase nitration of benzene with aqueous nitric acid (65%) at 170 °C over post-synthetic dealuminated Y, ZSM-5 and Mordenite zeolites by high temperature and acid treatment. This treatment reduces the framework as well as the nonframework aluminium content, which results in... 

Fig. 4.7. Aluminium content of sputter deposited ZnO Al films. A target with a nominal A1 content of 2wt% has been used. The shadowed regions indicate the general behavior. The atomic concentration is calculated with and without considering the high binding energy oxygen species, which contributes to the O Is signal (see Sect. 4.2.2.2)...

When USY zeolite is reacted with a lower concentration and lower adding speed of nitric acid solution, only the non - framework aluminium species located in the pores are extracted and H+ ions could not attack the zeolite skeleton, The non - framework aluminium content of USY zeolites decreases with increasing the concentration and adding speed of acid solution. ... 

A low digest volume-to-sample size ratio, e.g. 0.5 g in 25 ml, must be used if flame spectrometry is to be employed for the determination of the aluminium content of plant materials. 

J. A. T. Pennington, Aluminium content of foods and diets, Food Addit. Cont., 5 (1988), 119-128. 

The as-synthesized TPA[si]-MFI sample appears to be slightly more stable than the aluminium-containing TPA si, Al] -MFI sample. This result is in agreement Hith the semi-empirical calculations of Ooms et al. (12) which show that in the absence of Hater, the aluminium-rich samples are less stable than the purely siliceous ones. HoHever the observed difference betneen the AfH° values is small because the aluminium content of the TPA Si, Al] -MFI sample is not very high (Si/Al = 31). 

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