Nickel alloys molybdenum

The composition of this alloy (54% nickel, 15% molybdenum, 15% chromium, 5% tungsten and 5% iron) is less susceptible to intergranular corrosion at welds. The presence of chromium in this alloy gives it better resistance to oxidizing conditions than the nickel/molybdenum alloy, particularly for durability in wet chlorine and concentrated hypochlorite solutions, and has many applications in chlorination processes. In cases in which hydrochloric and sulfuric acid solutions contain oxidizing agents such as ferric and cupric ions, it is better to use the nickel/molybdenum/ chromium alloy than the nickel/molybdenum alloy. 

Steel is the most common constructional material, and is used wherever corrosion rates are acceptable and product contamination by iron pick-up is not important. For processes at low or high pH, where iron pick-up must be avoided or where corrosive species such as dissolved gases are present, stainless steels are often employed. Stainless steels suffer various forms of corrosion, as described in Section 53.5.2. As the corrosivity of the environment increases, the more alloyed grades of stainless steel can be selected. At temperatures in excess of 60°C, in the presence of chloride ions, stress corrosion cracking presents the most serious threat to austenitic stainless steels. Duplex stainless steels, ferritic stainless steels and nickel alloys are very resistant to this form of attack. For more corrosive environments, titanium and ultimately nickel-molybdenum alloys are used. 

N ickel-chromium-molybdenum (tungsten) alloys Nickel—molybdenum alloys Nickel-molybdenum catalysts Pb Mo6S8... 

Powder Formation. Metallic powders can be formed by any number of techniques, including the reduction of corresponding oxides and salts, the thermal dissociation of metal compounds, electrolysis, atomization, gas-phase synthesis or decomposition, or mechanical attrition. The atomization method is the one most commonly used, because it can produce powders from alloys as well as from pure metals. In the atomization process, a molten metal is forced through an orifice and the stream is broken up with a jet of water or gas. The molten metal forms droplets to minimize the surface area, which solidify very rapidly. Currently, iron-nickel-molybdenum alloys, stainless steels, tool steels, nickel alloys, titanium alloys, and aluminum alloys, as well as many pure metals, are manufactured by atomization processes. 

Nickel alloy 600 Nickel-molybdenum alloy B-2 N06600 7.4 13.3 20-90... 

Fie. 5.29 Anodic polarization curves for nickel-molybdenum alloys in 1 N H2S04. Redrawn from Ref 26... 

K. Tachibana and M.B. Ives, Selective Dissolution Measurements to Determine the Nature of Films on Nickel-Molybdenum Alloys, Passivity of Metals, The Electrochemical Society, 1978, p 878-897... 

In the environmental series, nickel is nobler than iron but more active than copper. Reducing environments, such as dilute sulfuric acid, find nickel more corrosion resistant than iron but not as resistant as copper or nickel-copper alloys. The nickel molybdenum alloys are more corrosion resistant to a reducing environment than nickel or nickel-copper alloys [16]. Nickel-based superalloys are extremely prone to weld cracking. 

Figure 8.15 Nickel-molybdenum alloy deposition, high concentration of NiS04 (1.0 mol dm ) and low concentration of Na2Mo04 (0.005 mol dm ), 0.7 mol sodium citrate, pH = 7.5, dependence on the rotation rate for 400, 1000, and 2000 rpm (Podlaha and Landolt). " (Reproduced with permission from J. Electrochem. Soc. 143, 885 (1996), 1996, The Electrochemical Society.)...

Figure 8.16 Nickel-molybdenum alloy deposition with a large Na2Mo04 concentration...

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