Metal baths

Two major sources of ultrasound are employed, namely ultrasonic baths and ultrasonic immersion hom probes [79, 71]- The fonuer consists of fixed-frequency transducers beneath the exterior of the bath unit filled with water in which the electrochemical cell is then fixed. Alternatively, the metal bath is coated and directly employed as electrochemical cell, but m both cases the results strongly depend on the position and design of the set-up. The ultrasonic horn transducer, on the other hand, is a transducer provided with an electrically conducting tip (often Ti6A14V), which is inuuersed in a three-electrode thenuostatted cell to a depth of 1-2 cm directly facing the electrode surface. 

The beaker and thermometer should be removed from the metal bath before the latter solidifies. Metal baths have the advantage that they do not smoke or catch fire they are, however, solid at the ordinary temperature and are usually too expensive for general use. 

One of the disadvantages of oil and metal baths is that the reaction mixture cannot be observed easily also for really constant temperatures, frequent adjustment of the source of heat is necessary. These difficulties are overcome, when comparatively small quantities of reactants are involved, in the apparatus shown in Fig. II, 5,4 (not drawn to scale). A... 

Place 50 g. of o-chloronitrobenzene and 75 g. of clean dry sand in a 250 ml. flask equipped with a mechanical stirrer. Heat the mixture in an oil or fusible metal bath to 215-225° and add, during 40 minutes, 50 g. of copper bronze or, better, of activated copper bronze (Section 11,50, 4) (1), Maintain the temperature at 215-225° for a further 90 minutes and stir continuously. Pour the hot mixture into a Pyrex beaker containing 125 g. of sand and stir until small lumps are formed if the reaction mixture is allowed to cool in the flask, it will set to a hard mass, which can only be removed by breaking the flask. Break up the small lumps by powdering in a mortar, and boil them for 10 minutes with two 400 ml. 

Method 1. a-Naphthonitrile. Place 80 g. (54 ml.) of redistilled a-bromonaphthalene (Section IV.20), 43 g. of dry powdered cuprous cyanide (Section II,50,J) and 36 g. (37 ml.) of dry pure pyridine (1) (Section 11,47.22) in a 250 ml. round-bottomed flask fitted with a ground-in reflux condenser carrying a calcium chloride (or cotton wool) guard tube, and heat the mixture in a metal bath at 215-225° for... 

The metal bath may bo replaced by a bath of hydrogenated cotton seed oil or of Silicone oil. 

Place 150 g. of benzoic acid, 150 g. (139 ml.) of acetic anhydride and 0-2 ml. of syrupy phosphoric acid in a 500 ml. bolt-head flask. Fit the latter with a two-holed stopper carrying a dropping funnel and an efficient fractionating column (compare Fig. 7/7, 61, 1) it is advisable to lag the latter with asbestos cloth. Set up the flask in an oil bath or in a fusible metal bath. Distil the mixture very slowly and at such a rate that the temperature of the vapour at the head of the column does... 

Place 30 g. of cycZobutane-1 I-dicarboxylic acid in a 100 ml. distilling flask, fitted with a thermometer, and connect the side arm to a 50 ml. Claisen flask supported in a funnel so that it can be cooled externally by rurming water. Heat the distilling flask in a metal bath at 160-170°... 

Cholestenone. Place a mixture of 1 0 g. of purified cholesterol and 0-2 g. of cupric oxide in a test-tube clamped securely at the top, add a fragment of Dry Ice in order to displace the air by carbon dioxide, and insert a plug of cotton wool in the mouth of the tube. Heat in a metal bath at 300-315° for 15 minutes and allow to cool rotate the test-tube occasionally in order to spread the melt on the sides. Warm with a few ml. of benzene and pour the black suspension directly into the top of a previously prepared chromatographic column (1) rinse the test-tube with a little more benzene and pour the rinsings into the column. With the aid of shght suction (> 3-4 cm. of mercury), draw the solution into the alumina column stir the top 0 -5 cm. or so with a stout copper wire to... 

Each type of metallic coating process has some sort of hazard, whether it is thermal energy, the reactivity of molten salt or metal baths, particulates in the air from spray processes, poisonous gases from pack cementation and diffusion, or electrical hazards associated with arc spray or ion implantation. 

Alternatively, tows of fibers can be passed through a Hquid metal bath, where the individual fibers are wet by the molten metal, wiped of excess metal, and a composite wine is produced. A bundle of such wines can be consoHdated by extmsion to make a composite. Another pressureless Hquid metal infiltration process of making MMCs is the Prim ex process (Lanxide), which can be used with certain reactive metal alloys such as Al—Mg to iafiltrate ceramic preforms. For an Al—Mg alloy, the process takes place between 750—1000°C ia a nitrogen-rich atmosphere (2). Typical infiltration rates are less than 25 cm/h. 

Another familiar commercial method is the immersion or hot-dipping process. The article to be coated is immersed in a molten metal bath. Usually httie else is done to change the properties of the coating, which adheres to the surface upon removal of the article from the bath. For a successful coating, an alloying action must take place between the components to some extent. Zinc and tin coatings are appHed to sheet steel by hot-dipping. 

The first successful direct-arc electric furnace, patented by Heroult in France, was placed in operation in 1899. The patent covered single- or multiphase furnaces with the arcs placed in series through the metal bath. This type of furnace, utilizing three-phase a-c power, was historically the most common for steel production. 

To the dry salt is added 0.3 g. of copper powder (Note 2), 81 g. (0.51 mole) of bromobenzene, and a few drops of guaiacol (Note 3). The mixture is stirred thoroughly with a glass rod the flask is fitted with an air condenser and heated in a metal bath (Note 4). A reaction becomes evident at a bath temperature of 160-180°, liquefaction occurs, and the color of the mixture changes to red or purple. The temperature is gradually raised to 200° and maintained at 200° for 2 hours. 

In using metal baths, the container (usually a metal crucible) should be removed while the metal is still molten. 

Basic oxygen furnaces (BOFs) have largely replaced open hearth furnaces for steelmaking. A water-cooled oxygen lance is used to blow high-purity oxygen into the molten metal bath. This causes violent agitation and rapid oxidation of the carbon, impurities, and some of the iron. The reaction is exothermic, and an entire heat cycle requires only 30-50 min. The atmospheric emissions from the BOF process are listed in Table 30-16. 

The aniline and sulphuric acid are cautiously mixed in a round flask (250 c.c.) and heated to 180—190° in an oil or metal bath for four to five hours until a sample dissolved in water remains clear on the addition of caustic soda in excess and no aniline separates. The product is poured into cold water, which precipitates the sulphanilic acid as a grey ciystalline mass.It is filtered, washed with a little cold water, recrystallised from hot water with the addition of a little animal charcoal, and dried in the air. Yield, 25 — 30 grams. 

Other specialized uses of Sn and its alloys are as type metal, as the molten-metal bath in the manufacture of float glass and as the alloy NbsSn in superconducting magnets. The many industrial and domestic uses of tin compounds are discussed in later sections these compounds account for about 15% of the tin produced worldwide. 

In a 1-L rbf attached to a Dean-Stark trap, equipped with a reflux condenser is placed distilled aniline (1, 46.5 g, 45.5 mL, 0.5 mol), commercially available ethyl acetoacetate (5, 65 g, 63.5 mL, 0.5 mol), benzene (100 mL) and glacial AcOH (1 mL). The flask is heated at about 125 °C, and the water which distills out of the mixture with the refluxing benzene is removed at intervals. Refluxing is continued until no more water separates (9 mL collects in about 3 hrs) and then for an additional 30 min. The benzene is then distilled under reduced pressure, and the residue is transferred to a 125 mL modified Claisen flask with an insulated column. The flask is heated in an oil or metal bath maintained at a temperature not higher than 120 °C while the forerun of 1 and 5 is removed and at 140-160 °C the product distills giving 78-82 g, 76-80% yield of 6. 

In a short path distilling apparatus is placed 3-5 g of 1,1-cyclohexanedicarboxylic acid. The flask is heated in an oil, sand, or metal bath to 160-170° until all the effervescence stops then the temperature of the bath is raised to 210°. Cyclobutanecarboxylic acid distills over at 191 -197°. It may be purified by redistillation at atmospheric pressure, bp 195-196°. 

Bad-kasten, m. (electrolytic) cell, -nitrieren, n. Metal.) fused-salt nitriding, -patentieren, n. Wire) patenting with cooling in a lead or salt bath, -spannung, /. bath tension, cell voltage, -Spiegel, m, bath level, bath surface, -zementieren, n. Metal.) bath cementation, liquid carburizing,... 

A. Wood s metal bath or a mixture (m. p. about 150°) of ten parts of potassium nitrate and seven and one-half parts of sodium nitrite may be used. 

Poly condensations of trimethylsilyl 3,5-diacetoxybenzoate Trimethylsilyl 3,5-diacetoxybenzoate (15.52 g, 50 mmol) is weighed into a cylindrical reactor equipped with a glass stirrer and gas inlet and outlet tubes. The reaction vessel is placed into a metal bath preheated to 200°C. The temperature is raised in 20°C steps over a period of 1 h and finally maintained at 280°C for 3 h. Vacuum is then applied for an additional 0.5 h. Finally, the cold reaction product is powdered, dissolved in CH2Cl2-trifluoroacetic acid (volume ratio 4 1), and precipitated into cold methanol. 

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