Monel composition

Fluorine cannot be prepared directly by chemical methods. It is prepared in the laboratory and on an industrial scale by electrolysis. Two methods are employed (a) using fused potassium hydrogen-fluoride, KHFj, ill a cell heated electrically to 520-570 K or (b) using fused electrolyte, of composition KF HF = 1 2, in a cell at 340-370 K which can be electrically or steam heated. Moissan, who first isolated fluorine in 1886, used a method very similar to (b) and it is this process which is commonly used in the laboratory and on an industrial scale today. There have been many cell designs but the cell is usually made from steel, or a copper-nickel alloy ( Monel metal). Steel or copper cathodes and specially made amorphous carbon anodes (to minimise attack by fluorine) are used. Hydrogen is formed at the cathode and fluorine at the anode, and the hydrogen fluoride content of the fused electrolyte is maintained by passing in... 

Materials of Construction and Operational Stress. Before a centrifugal separation device is chosen, the corrosive characteristics of the Hquid and soHds as weU as the cleaning and saniti2ing solutions must be deterrnined. A wide variety of materials may be used. Most centrifuges are austenitic stainless steels however, many are made of ordinary steel, mbber or plastic coated steel. Monel, HasteUoy, titanium, duplex stainless steel, and others. The solvents present and of course the temperature environment must be considered in elastomers and plastics, including composites. 

The reaction mixture is filtered. The soHds containing K MnO are leached, filtered, and the filtrate composition adjusted for electrolysis. The soHds are gangue. The Cams Chemical Co. electrolyzes a solution containing 120—150 g/L KOH and 50—60 g/L K MnO. The cells are bipolar (68). The anode side is monel and the cathode mild steel. The cathode consists of small protmsions from the bipolar unit. The base of the cathode is coated with a corrosion-resistant plastic such that the ratio of active cathode area to anode area is about 1 to 140. Cells operate at 1.2—1.4 kA. Anode and cathode current densities are about 85—100 A/m and 13—15 kA/m, respectively. The small cathode areas and large anode areas are used to minimize the reduction of permanganate at the cathode (69). Potassium permanganate is continuously crystallized from cell Hquors. The caustic mother Hquors are evaporated and returned to the cell feed preparation system. 

Nonmagnetic drill collars are manufactured from various alloys, although the most common are Monel K500 (approximately 68% nickel, 28% copper with some iron and manganese, and 316L austenitic stainless steel). A stainless steel with the composition of 0.06% carbon, 0.50% silicon, 17-19% manganese, less than 3.50% nickel, 12% chromium, and 1.15% molybdenum, with mechanical properties of 110 to 115 Ksi tensile strength is also used. 

The activity tests of the catalyst were carried out in a microflow reactor set-up in which all the high temperature parts are constructed of hastelloy-C and monel. The reactor effluent was analyzed by an on-line gas chromatograph with an Ultimetal Q column (75 m x 0.53 mm), a flame ionization detector, and a thermal conductivity detector. The composition of the feed to the reactor can be varied, besides the temperature, pressure, and space velocity. The influence of the recycle components CHCIF2 and methane was tested by adding these components to the feed. In total five stability experiments of over 1600 hours were performed. In each... 

For the following pairs of alloys that are coupled in seawater, predict the possibility of corrosion and if corrosion is possible, note which alloy will corrode (a) Al/Mg (b) Zn/low carbon steel (c) brass/Monel (d) titanium/304 stainless steel and (e) cast iron/315 stainless steel. Clearly state any assumptions you make about compositions of alloys. 

The processes involved in the reduction of nickel ores vary considerably, both with the chemical composition of the ore employed and the nature of the product required. For example, the Sudbury (Ontario) ores consist essentially of sulphides of nickel, copper, and iron. When pure nickel is required it is, of course, essential to remove the copper and the iron. Sometimes, however, an alloy of nickel and copper, known as monel metal, is desired, and it is usual then to remove the iron and subsequently reduce the mixed sulphides of copper and nickel to the alloy direct. Monel metal is thus known as a natural alloy, inasmuch as the constituent elements have not been individually isolated. 

Corrosion pitting in seawater is observed largely above 40% Ni because pit growth is favored by passive-active cells (see Section 6.5), and such cells can operate only when the alloy is passive—that is, in the range of high nickel compositions. Practically, this distinction is observed in the specification of materials for seawater condenser tubes in which pitting attack must be rigorously avoided. The cupro nickel alloys are used (10-30% Ni), but not Monel (70% Ni-Cu). 

There are some differences in the behavior of alloys due to the variations in caustic composition among the three cell processes. These differences occur mostly in lower-grade applications using materials less robust than nickel. Monel, for example, is subject to liquid-metal cracking by mercury and its salts. Stainless steels seem to be equally affected by diaphragm- and mercury-cell caustic, but if the caustic is consumed in some application, the residual chloride from diaphragm-cell NaOH can cause stress corrosion cracking [146]. 

The first nickel alloy, invented in 1905, was approximately two-thirds nickel and one-third copper. The present equivalent of the alloy. Monel 400, remains one of the widely used nickel alloys. Refer to Table 15.3 for the chemical composition. 

Monel alloy 405 is a higher sulfur grade in which the sulfur content is increased over that of alloy 400 to improve machinability. Refer to Table 15.3 for the chemical composition. The corrosion resistance of this alloy is essentially the same as alloy 400. 

Monel alloy K-500 is an age-hardenable alloy that combines the excellent corrosion resistance characteristics of alloy 400 with the added advantage of increased strength and hardness. Qiemical composition will be found in Table 15.3. 

The actual compositions of malodors are invariably even more complex than those just quoted and one which has received considerable attention is sweat-generated body malodor. Quite remarkably, it was only as recently as 1990 that Dr. George Preti of Monell reported at an American Chemical Society meeting that 3-methyl-2-hexenoic acid is the chief cause of underarm odor. It had previously been widely assumed that combinations of isovaleric acid and androstenol were the guilty parties [56]. A subsequent patent taken out by Monell [57] contains detailed compositions and comprehensive references. 

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