Nichrome

The furnace and thermostatic mortar. For heating the tube packing, a small electric furnace N has been found to be more satisfactory than a row of gas burners. The type used consists of a silica tube (I s cm. in diameter and 25 cm. long) wound with nichrome wire and contained in an asbestos cylinder, the annular space being lagged the ends of the asbestos cylinder being closed by asbestos semi-circles built round the porcelain furnace tube. The furnace is controlled by a Simmerstat that has been calibrated at 680 against a bimetal pyrometer, and the furnace temperature is checked by this method from time to time. The furnace is equipped with a small steel bar attached to the asbestos and is thus mounted on an ordinary laboratory stand the Simmerstat may then be placed immediately underneath it on the baseplate of this stand, or alternatively the furnace may be built on to the top of the Simmerstat box. 

Excellent results are obtained by passing acetone vapour over an electrically heated nichrome wire spiral an apparatus, incorporating the latter, is described in the experimental section. 

Chapter III. 1 Heptene (111,10) alkyl iodides (KI H3PO4 method) (111,38) alkyl fluorides (KF-ethylene glycol method) (111,41) keten (nichrome wire method) (111,90) ion exchange resin catalyst method for esters (111,102) acetamide (urea method) (111,107) ethyl a bromopropionate (111,126) acetoacetatic ester condensation using sodium triphenylmethide (111,151). 

Nickel, used extensively to make coins and nickel steel for armor plates and burglar-proof vaults, and is also a component in Nichrome(R), Permalloy(R), and constantan. 

Heating and Cooling. Heat must be appHed to form the molten zones, and this heat much be removed from the adjacent sohd material (4,70). In principle, any heat source can be used, including direct flames. However, the most common method is to place electrical resistance heaters around the container. In air, nichrome wine is useflil to ca 1000°C, Kanthal to ca 1300°C, and platinum-rhodium alloys to ca 1700°C. In an inert atmosphere or vacuum, molybdenum, tungsten, and graphite can be used to well over 2000°C. 

Forced-convection pit furnaces are employed for heat-treating small metal parts in biuk. Small pieces are suspended in a mesh-bottom basket, while larger pieces are placed on racks. Air heating is by means of Nichrome electric coils set in refractory walls around the... 

Aluminum triethyl (triethyl aluminum) [97-93-8] M 114.2, b 69°/1.5mm, 76°/2.5mm, 129-131°/55mm, d 0.695, n 1.394. Purified by fractionation in an inert atmosphere under vacuum in a 50cm column containing a heated nichrome spiral, taking the fraction 112-114°/27mm. It is very sensitive to H2O and should be stored under N2. It should not contain chloride which can be shown by hydrolysis and testing with AgN03. [J Am Chem Soc 75 4828 51937953 NMR J Am Chem Soc 81 3826 7959.]... 

Distd from excess dry NaCI (to remove ethyl aluminium dichloride) in a 50-cm column containing a heated nichrome spiral. 

Nickel alloys include monels (Ni-Cu alloys), nichromes (Ni-Cr alloys), nimonics and nickel-based super-alloys (Ni-Fe-Cr-Al-Co-Mo alloys). 

The composition of the filament is of importance in determining the yield and the performance of the apparatus. With nickel-chromium alloys excessive carbonization occurs and the yield is poor. Much better results are obtained with the nickel-iron-chromium alloys called Chromel C and Nichrome AUoy Wire. 

A heavy nichrome wire twisted into 4 loops (similar to an egg beater) was found to be very satisfactory. The two ends of the wire, extending several inches beyond the loops, were pushed into a piece of glass tubing for the stirrer shaft. 

Around 1930, in Ameriea, presumably with the early superchargers in mind, several metallurgists sought to improve the venerable alloy used for eleetric heating elements, 80/20 nickel-chromium alloy (nichrome), by adding small amounts of titanium and aluminum, and found significant increase in creep resistance. 

Hot wire anemometer An instrument for the measurement of fluid velocity by measuring the resistance of a fine platinum or nichrome wire, which may or may not be shielded by a silica tube. The wire resistance is proportional to the temperature and the fluid flow rate. 

The non-ferrous alloys include the misleadingly named nickel silver (or German silver) which contains 10-30% Ni, 55-65% Cu and the rest Zn when electroplated with silver (electroplated nickel silver) it is familiar as EPNS tableware. Monel (68% Ni, 32% Cu, traces of Mn and Fe) is used in apparatus for handling corrosive materials such as F2 cupro-nickels (up to 80% Cu) are used for silver coinage Nichrome (60% Ni, 40% Cr), which has a very small temperature coefficient of electrical resistance, and Invar, which has a very small coefficient of expansion are other well-known Ni alloys. Electroplated nickel is an ideal undercoat for electroplated chromium, and smaller amounts of nickel are used as catalysts in the hydrogenation of unsaturated vegetable oils and in storage batteries such as the Ni/Fe batteries. 

Niobium appears to have a slightly beneficial effect on the oxidation resistance of nickel-chromium-base alloys, although at 1 200°C the addition of niobium to Nichrome (Table 7.18) produces a much higher rate constant. Titanium on the other hand appears to have a slightly deleterious effect on oxidation resistance at low temperatures. 

It has been observed2 that the dropwise addition of an aqueous solution of potassium ethyl xanthate to a cold (0°) aqueous solution of diazotized orthanilic acid results in the immediate loss of nitrogen when a trace of nickel ion is present in the stirred diazonium solution.3 The catalyst can be added as nickelous chloride or simply by using a nichrome wire stirrer. When no nickel ion is added and a glass stirrer is employed, the diazonium xanthate precipitates and requires heat (32°) to effect decomposition. 

The use of a nichrome stirrer or a catalytic amount of nickel ion is recommended 1 for such reactions to minimize the accumulation of diazonium xanthate however, the catalytic role of nickel ion has not been explored with other diazonium salts. 

Metallic chromium is an ingredient of several important alloys. Some forms of stainless steel, for example, contain about 12% Cr. Nichrome, which is commonly used for heating coils, has about 15% Cr in addition to 60% Ni and 25% iron. Both these alloys are quite resistant to chemical oxidation. 

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