Nickel service temperature

Plain Carbon and Low Alloy Steels. For the purposes herein plain carbon and low alloy steels include those containing up to 10% chromium and 1.5% molybdenum, plus small amounts of other alloying elements. These steels are generally cheaper and easier to fabricate than the more highly alloyed steels, and are the most widely used class of alloys within their serviceable temperature range. Figure 7 shows relaxation strengths of these steels and some nickel-base alloys at elevated temperatures (34). 

The successful application of nickel-chromium-iron alloys as structural components of industrial furnaces and as chambers and containers in chemical processing under conditions of exposure involving sulphur substantiates their good resistance to this form of corrosion. These materials are used for service temperatures in the range 750-1 200°C, the upper limit of serviceability being determined largely by the chromium content of a particular alloy. Results of corrosion tests (Table 7.24) on cast nickel-... 

Borosilicate glasses have a maximum service temperature of the order of 500°C and, with some compositions, 600°C. Selected types are used to make matching seals with iron-nickel-cobalt alloy, with molybdenum and with tungsten. The softening temperature depends on the composition and is about 625°C. 

The most common matrices are the low-density metals, such as aluminum and aluminum alloys, and magnesium and its alloys. Some work has been carried out on lead alloys, mainly for bearing applications, and there is interest in the reinforcement, for example, of titanium-, nickel- and iron-base alloys for higher-temperature performance. However, the problems encountered in achieving the thermodynamic stability of fibers in intimate contact with metals become more severe as the potential service temperature is raised, and the bulk of development work at present rests with the light alloys. 

Section 9.3.2.1 discusses materials of construction for NaOH and KOH in some detail a short summary of their application to product tankage follows here. Carbon steel is the standard material of construction for NaOH and KOH below 50°C. Corrosion allowances of about 3 mm usually apply. Welds should be made with rods containing 2% Mo. Stress relief can extend the serviceable temperature range (Fig. 14.21), but Ae danger of contamination of the caustic continues to increase. If temperatures may occasionally be higher or if product contamination is a major consideration, tanks are lined or coated. Rubber and thermoplastic coating systems are widely used, and some tanks are lined with metal sheets or cladding. When more resistant metals are necessary, stainless steel and nickel also appear in this service. Stainless steels offer improved... 

The service temperature of a particular stainless steel can be found elsewhere [17]. Recently published stainless steel, carbon steel and nickel data on oxidation clearly exhibit increasing oxide thickness growth with increasing temperature as summarized in Figure 10.13 after one year of exposure in air [18]. 

One of the most important attributes of nickel with respect to the formation of corrosion-resistant alloys is its metallurgical compatibility with a number of other metals, such as copper, chromium, molybdenum, and iron. A survey of the binary phase diagrams for nickel and these other elements shows considerable solid solubility, and thus one can make alloys with a wide variety of composition. Nickel alloys are, in general, all austenitic alloys however, they can be subject to precipitation of intermetallic and carbide phases when aged. In some alloys designed for high-temperature service, intermetallic and carbide precipitation reactions are encouraged to improve properties. However, for corrosion applications, the precipitation of second phases usually promotes corrosion attack. The problem is rarely encountered because the alloys are supplied in the annealed condition and the service temperatures rarely approach the level required for sensitization. 

The rotor tips are usually clad in electroformed nickel sheet this is chemically pretreated (usually a nitric acid etch [35]), primed and then bonded with a film adhesive curing at 120-130°C. In some cases, due to the increased service temperature requirements caused by underlying heater mats, an adhesive is used, which has enhanced temperature performance. 

Niobium s ductile-to-brittle transition temperature ranges from -101 to - 157°C. This metal also has the low thermal neutron capture cross section required for nuclear applications. Its high melting point warrants its use at temperatures above the maximum service temperatures of the iron-, nickel-, and cobalt-base metals. It has excellent ductility and fabricability. 

Nickel Acetate aqueous solution or solid 121 8 Exposure temperature is maximum recommended service temperature Kynar Atochem... 

In sulphur/accelerator crosslinked EPDMs, only nickel butyl dithiocar-bamate has been found to be effective as an antioxidant. The by-products of the various cure systems probably also act as antioxidants, but experience has shown that it is not necessary to protect EPM and EPDM based compounds when service temperatures do not exceed 100°C. 

To achieve higher efficiency and performance of gas turbine engines, the inlet gas temperature should be inaeased. Currently, the operating temperature on high pressure turbine engines is approaching 1150°C, which is very close to the maximum melting point of the most advanced nickel-based superalloys ( 1350°C). The service temperature of intermetallic compounds based on Ni-Al and Ti-Al cannot meet the requirements for use in the hot part of... 

Standard commercial iastmmentation and control devices are used ia fluorine systems. Pressure is measured usiag Bourdon-type gauges or pressure transducers. Stainless steel or Monel constmction is recommended for parts ia contact with fluoriae. Standard thermocouples are used for all fluorine temperature-measuriag equipment, such as the stainless-steel shielded type, iaserted through a threaded compression fitting welded iato the line. For high temperature service, nickel-shielded thermocouples should be used. 

Appllca.tlons. The principal appHcations of nickel-base superalloys are in gas turbines, where they are utilized as blades, disks, and sheet metal parts. Abcraft gas turbines utilized in both commercial and military service depend upon superalloys for parts exposed to peak metal temperatures in excess of 1000°C. Typical gas turbine engines produced in the United States in 1990 utilized nickel and cobalt-base superalloys for 46% of total engine weight (41). However, programs for future aerospace propulsion systems emphasize the need for lightweight materials having greater heat resistance. For such apphcations, intermetallics matrix composites and ceramic composites are expected to be needed. 

Materials of Construction. Glass has excellent corrosion-resistance to wet or dry bromine. Lead is very usefiil for bromine service if water is less than 70 ppm. The bromine corrosion rate increases with concentrations of water and organics. Tantalum and niobium have excellent corrosion-resistance to wet or dry bromine. Nickel has usefiil resistance for dry bromine but is rapidly attacked by wet bromine. The fluoropolymers Kynar, Halar, and Teflon are highly resistant to bromine but are somewhat permeable. The rate depends on temperature, pressure, and stmcture (density) of fluoropolymer (63). 

With cobalt historically being approximately twice the cost of nickel, cobalt-base alloys for both high temperature and corrosion service tend to be much more expensive than competitive alloys. In some cases of severe service their performance iacrease is, however, commensurate with the cost iacrease and they are a cost-effective choice. For hardfaciag or wear apphcations, cobalt alloys typically compete with iron-base alloys and are at a significant cost disadvantage. 

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