Sulphur in nickel

For nickel and its alloys the dependence of the corrosion resistance on the sulphur content is even more characteristic than it is for copper, especially at higher temperatures. 

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The same problems exist thus with the determination of sulphur in nickel as with sulphur in copper. Also here, the dissolution methods are the more accurate ones. In any case, the combustion methods need reference materials with known sulphur contents to establish a reliable calibration. 

The tlrermodynamic activity of nickel in the nickel oxide layer varies from unity in contact with tire metal phase, to 10 in contact with the gaseous atmosphere at 950 K. The sulphur partial pressure as S2(g) is of the order of 10 ° in the gas phase, and about 10 in nickel sulphide in contact with nickel. It therefore appears that the process involves tire uphill pumping of sulphur across this potential gradient. This cannot occur by the counter-migration of oxygen and sulphur since the mobile species in tire oxide is the nickel ion, and the diffusion coefficient aird solubility of sulphur in the oxide are both vety low. 

Dilute binary alloys of nickel with elements such as aluminium, beryllium and manganese which form more stable sulphides than does nickel, are more resistant to attack by sulphur than nickel itself. Pfeiffer measured the rate of attack in sulphur vapour (13 Pa) at 620°C. Values around 0- 15gm s were reported for Ni and Ni-0-5Fe, compared with about 0-07-0-1 gm s for dilute alloys with 0-05% Be, 0-5% Al or 1-5% Mn. In such alloys a parabolic rate law is obeyed the rate-determining factor is most probably the diffusion of nickel ions, which is impeded by the formation of very thin surface layers of the more stable sulphides of the solute elements. Iron additions have little effect on the resistance to attack of nickel as both metals have similar affinities for sulphur. Alloying with other elements, of which silver is an example, produced decreased resistance to sulphur attack. In the case of dilute chromium additions Mrowec reported that at low levels (<2%) rates of attack were increased, whereas at a level of 4% a reduction in the parabolic rate constant was observed. The increased rates were attributed to Wagner doping effects, while the reduction was believed to result from the... 

It is widely recognised that improved resistance to sulphur attack can be obtained in commercial alloys by small additions of certain elements, notably manganese, silicon and aluminium. Figure 7.43 shows how the depth of metal converted to scale, and more particularly the total penetration by sulphur, is reduced by increasing silicon content in nickel-chromium-iron... 

Sulphur attack on nickel-chromium alloys and nickel-chromium-iron alloys can arise from contamination by deposits resulting from the combustion of solid fuels, notably high-sulphur coals and peat. This type of corrosion, which has been observed on components of aircraft, marine and industrial gas turbines and air heaters, has been associated with the presence of metal-sulphate and particularly sodium sulphate arising directly from the fuel or perhaps by reaction between sodium chloride from the environment with sulphur in the fuel. Since such fuels are burned with an excess of air, corrosion occurs under conditions that are nominally oxidising although the deposits themselves may produce locally reducing conditions. 

Isopropyl (/ )-( —)-methylphosphinate (134) has been prepared" in > 90% optical purity by Raney nickel desulphurization of optically pure O-isopropyl (5)-(-f-)-methyIphosphonothioate (135). The phosphonate (134) is rapidly racemized by base, but not by acid, unlike secondary phosphine oxides"" [although whether these have been prepared optically active now seems doubtful (see Chapter 4)]. The phosphinate (134) can be reconverted into 89% optically pure (5)-( + )-(135) by addition of sulphur in dioxan. As shown in the Scheme, a series of interconversions has been used to establish the configurations. 

Niskavaara, H., Reimann, C. and Chekushin, V. (1996) Distribution and pathways of heavy metals and sulphur in the vicinity of the copper-nickel smelters in Nikel and Zapoljarnij, Kola Peninsula, Russia, as revealed by different sample media. Applied Geochemistry, 11(1-2), 25-34. 

Nickel Sesquisulphide, Ni2S3.—A substance of this composition may be obtained by acting on nickel carbonyl with a solution of sulphur in carbon disulphide.1... 

Double sulphides of iron and nickel are present in nickel matte, and are hence of commercial importance. Double sulphides with potassium, K2S.3NiS, and barium, BaS.4NiS, may be obtained by fusing nickel, sulphur, and an alkali at a high temperature.8 They are crystalline compounds. Cobalt yields only the sesquisulphide, Co2S3, in like circumstances. Nickel thus resembles palladium and platinum, whilst cobalt resembles rhodium and iridium in these respects. The position of nickel after cobalt in the Periodic Table thus receives further justification. 

Fig. 15. Corrosion-potential curves of Cr-Ni stainless steels in sulphuric acid. Solid line represents a steel lower in chromium and higher in nickel than the dotted line (44).

Several publications have reported that composites of molybdenum disulphide with a high nickel content were not satisfactory , and nickel alloys are recognised to be susceptible to attack by sulphur or sulphur compounds at elevated temperatures. Al tman et al found that certain alloying elements, especially molybdenum, can stabilise the composite structures. However, the adverse reports of composites in nickel are not universal, and a few successful examples will be described later. 

Sulphur is the main source for deactivation of reforming catalysts (1). An effective desulpurization of the hydrocarbons and a proper purity of the boiler feed water for steam production are therefore very important. The prereforming catalyst is deactivated slowly by sulphur poisoning (1,8,9) reflected by the progressive movement of the temperature profile as illustrated in Fig. 9. Due to the low temperature, traces of sulphur in the feed are removed completely over the prereforming catalyst as reflected by the low equilibrium ratios (1) for chemisorption on nickel (6 = 0.5 for H2S/H2 = 2-10 at 450°C). This means that not only the catalyst in the tubular reformer but also downstream catalysts, especially the Cu-based shift catalysts are protected against sulphur poisoning. 

EINECS 232-104-9 HSDB 1114 NCI-C60344 Nickel sulfate Nickel sulfate (NiS04) Nickel sulfate(1 1) Nickel sulphate Nickel(2+) sulfate Nickel(ll) sulfate Nickelous sulfate NSC 51152 Sulfuric acid, nickel(2+) salt (1 1) Sulphuric acid, nickel(ll) salt. Also occurs as the hexahydrate [10101-97-0 232-104-9] and the heptahydrate [10101-98-1 205-788-1]. Used in the electroplating trade, Hexahydrate loses 5H2O at 100 and becomes anhydrous at 280. Soluble in H2O (0.7 g/ml) LDso (gpg sc) 62 mg/kg. 

The partial pressure of sulphur in equilibrium with nickel sulphide was determined at... 

The activity of sulphur in dilute solutions of sulphur in pure nickel melts was investigated at three different temperatures, viz. 1773, 1823 and 1848 K, for concentrations up to 0.7 wt% S. A gas mixture of H2(g) and H2S(g) was equilibrated with liquid nickel at a constant gas stream through the fiimace. The compositions of both the gas mixture and the equilibrated liquid phase were determined by chemical analysis. When 82(g) is the reference state for sulphur, the activities of sulphur in the nickel melt can be calculated from the well-known gas phase equilibrium ... 

Batteries that require a liquid electrolyte are called wet batteries. Corrosive battery fluid refers to either acid electrolytes syn. battery acid, like the common lead-acid automobile battery which uses a solution of sulphuric acid, or alkali electrolytes syn. alkaline corrosive battery fluid, like potassium hydroxide (1310-58-3) solutions in nickel-cadmium and other alkaline battery systems. Dry batteries or dry cells, like all primary batteries, use electrolytes immobilized in pastes, gels, or absorbed into separator materials. Some batteries are loaded with a dry, solid chemical (e.g., potassium hydroxide) which is diluted with water to become a liquid electrolyte. The hazards associated with handling and transportation prior to use are thereby reduced. 

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