Hot water seal

Pressurization of medium- and high-temperature hot water sealed heating systems referred to above may take the following forms. 

The effect of hot water sealing is to convert anhydrous y-AljO, into the crystalline monohydrate, AljOj.HjO, which occupies a greater volume and blocks up the pores, thus preventing further absorption of dyes or contaminants. The monohydrate is also less reactive. 

Hot water seal is a heated water bath (heated to approximately 180°F) used to seal the surface coating on formed aluminum that has been anodized and coated. In establishing an effluent allowance for this operation, the hot water seal shall be classified as a cleaning or etching rinse. 

Alexis Antibloom. [Alluight Wilson Am.] Proi ietaty metal finishing additive for hot water sealing of anodized aluminum to prevent sealing bloom. 

Figure 7-12 shows Bode plots of freshly anodized hot water sealed Al 7505 samples, which demonstrate the effect of local defects (Jiittner et al., 1989). Two curves were obtained in 0.5 M NaCl after drilling a certain number of artificial pits. In the presence of Cr, perfect re-passivation of the oxide film is not possible and localized active metal dissolution takes place. Under these conditions, the active pit model C is applicable and the full line curves in Fig. 7-12 show the optimum fit. 

Anodized coatings on SiC/aluminum composites provide satisflictoiy corrosion protection, but they are not as effective as anodized coatings are for unieinfor-ced aluminum because the structure of the anodized layer is affected by the SiC particulates (the particulates interfere with the formation of a continuous barrier layer). TaUe 3 shows a comparison of pitting times and crevice times for sulfriric acid-an ized samples with a hot water seal with those of hard anodized SiCyahiminum. The corrosion resistance of the hard aiaxlized SiC/aluminum is less than that of the conventional anodized SiC/aluminum because the area fraction of the continuous barrier layer for hard anodized SiC/ahiminum is less than that for conventionally anodized SiC/alimiinum. 

HWS, anodized and hot water sealed DS, anodized and dichromate sealed. The specimens were immersed in 0.5 AtNaQ. (a) Alloy A356 MMC samples were cast Al203/aluminum alloys MMCs were cast and extiuded all other samples processed by P/M methods. Source ... 

During processing, the extrusions were machined on the flat side, oiled, deburred, hot formed, cleaned, penetrant inspected, covered with oil, and then shot peened. They were then recoated with oil, shipped to a second vendor, hand wiped with a solvent, alkaline cleaned, acid desmutted, sulfuric acid anodized, and hot water sealed. 

Equip a 1 Utre three-necked flask or a 1 litre bolt- head flask with a reflux condenser and a mercury-sealed stirrer. Dissolve 50-5 g. of commercial 2 4-dinitro-l-chlorobenzene in 250 ml. of rectified spirit in the flask, add the hydrazine solution, and reflux the mixture with stirring for an hour. Most of the condensation product separates during the first 10 minutes. Cool, filter with suction, and wash with 50 ml. of warm (60°) rectified spirit to remove unchanged dinitrochlorobenzene, and then with 50 ml. of hot water. The resulting 2 4-dinitrophenylhydrazine (30 g.) melts at 191-192° (decomp.), and is pure enough for most purposes. Distil oflF half the alcohol from the filtrate and thus obtain a less pure second crop (about 12 g.) recrystallise this from n-butyl alcohol (30 ml. per gram). If pure 2 4-dinitrophenylhydrazine is required, recrystallise the total yield from n-butyl alcohol or from dioxan (10 ml. per gram) this melts at 200° (decomp.). 

Bismuth ttiiodide may be prepared by beating stoichiometric quantities of the elements in a sealed tube. It undergoes considerable decomposition at 500°C and is almost completely decomposed at 700°C. However, it may be sublimed without decomposition at 3.3 kPa (25 mm Hg). Bismuth ttiiodide is essentially insoluble in cold water and is decomposed by hot water. It is soluble in Hquid ammonia forming a red triammine complex, absolute alcohol (3.5 g/100 g), benzene, toluene, and xylene. It dissolves in hydroiodic acid solutions from which hydrogen tetraiodobismuthate(Ill) [66214-37-7] HBil 4H2O, may be crystallized, and it dissolves in potassium iodide solutions to yield the red compound, potassium tetraiodobismuthate(Ill) [39775-75-2] KBil. Compounds of the type tripotassium bismuth hexaiodide [66214-36-6] K Bil, are also known. 

Ninhydrin (1,2,3-triketohydrindene hydrate) [485-47-2] M 178.1, m 241-243 (dec), pK 8.82. Crystd from hot water (charcoal). Dried under vacuum and stored in a sealed brown container. 

No need to cool hot water - If the seal s elastomer can take the temperature, and the fluid is pressurized above its vapor pre.ssure, the cooling line can be eliminated. 

In a 2-1. three-necked round-bottomed flask, fitted with an efficient sealed stirrer and a reflux condenser capped by a drying tube, are placed the dried anisyl chloride (Notes 2 and 3), 73.6 g. (1.5 moles) of finely powdered sodium cyanide, 10 g. of sodium iodide, and 500 ml. of dry acetone (Note 4). The heterogeneous reaction mixture is heated under reflux with -sngorous stirring for 16-20 hours, then cooled and filtered with suction. The solid on the filter is washed with 200 ml. of acetone and discarded (Note 5). The combined filtrates are distilled to remove the acetone. The residual oil is taken up in 300 ml. of benzene and washed with three 100-ml. portions of hot water. The benzene solution is dried over anhydrous sodium sulfate for about 15 minutes, and the solvent is removed by distillation at the reduced pressure of the water aspirator (Note 6). The residual -methoxyphenyl-acetonitrile is purified by distillation under reduced pressure through an 8-in. Vigreux column b.p. 94—97°/0.3 mm. 1.5285-1.5291. The yield is 109-119 g., or 74-81% based on anisyl alcohol (Notes 7 and 8). 

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