Sulphur content

Prepare a saturated solution of sodium sulphide, preferably from the fused technical sodium polysulphide, and saturate it with sulphur the sulphur content should approximate to that of sodium tetrasulphide. To 50 ml. of the saturated sodium tetrasulphide solution contained in a 500 ml. round-bottomed flask provided with a reflux condenser, add 12 -5 ml. of ethylene dichloride, followed by 1 g. of magnesium oxide to act as catalyst. Heat the mixture until the ethylene dichloride commences to reflux and remove the flame. An exothermic reaction sets in and small particles of Thiokol are formed at the interface between the tetrasulphide solution and the ethylene chloride these float to the surface, agglomerate, and then sink to the bottom of the flask. Decant the hquid, and wash the sohd several times with water. Remove the Thiokol with forceps or tongs and test its rubber-like properties (stretching, etc.). 

The sulphur pressure of tire sulphides is a sensitive function of die tnetal/sulphur ratio around the stoichiometric composition, rising sharply when the sulphur content exceeds this limit. It follows from die Gibbs-Duhem equation... 

Table 4.1 Dependence of the glass transition of rubber on the sulphur content...

EEC Directive amending Directive 76/116/EEC m respect of the calcium, magnesium, sodium and sulphur content of fertilizers... 

SI 2000/1460 The Sulphur Content of Liquid Euels (England and Wales) Regulations... 

EC Directive amending 93/12/EC on the sulphur content of liquid fuels... 

EC Directive relating to a reduction in the sulphur content of certain liquid fuels and amending... 

Starnes and Plitz [51], in their studies of PVC stabilization with di( -butyl)tin bis ( -dodecyl mercaptide) or with mixtures of the mercaptide and di( -butyl)tin dichloride, found that the rate of dehydrochlorination was inversely related to the amount of sulphur content of approximately 0.9%. The following mechanism of allyl chloride substitution was proposed [Eq. (12)]. 

All the stainless steels can be machined in the softened states, but they may present some problems unless the correct techniques are adopted. This is especially so with the austenitic grades where the extreme ductility minimises chip breaking and the work hardening may cause difficulties unless modest cuts are made. The free-cutting grades (those with high sulphur contents or selenium additions) are much easier to machine, but it must be remembered that they have somewhat reduced corrosion resistance, ductility and weldability compared to their normal counterparts. Detailed machining instructions are readily available from steel suppliers. 

This work has been carried out by Marcus and his co-workersand deals with the influence of sulphur on the passivation of Ni-Fe alloys. For sulphur-containing Ni-Fe alloys, sulphur segregates on the surface during anodic dissolution. Above a critical sulphur content a non-protective thin sulphide film is formed on the surface instead of the passive oxide film. 

Copper additions appear to have the particular effect of reducing the corrosion stimulating effect of the sulphur content of an iron exposed to acid and the effect is thus less marked in low sulphur irons. Because sulphur can stimulate corrosion in acidic environments, it is usually kept as low as possible in irons to be used under these conditions. A low sulphur content is in any case metallurgically desirable. 

The presence of active sulphate-reducing bacteria usually results in graphitic corrosion and this has led to a useful method of diagnosing this cause of corrosion. The leaching out of iron from the graphitic residue which is responsible for the characteristic appearance of this type of corrosion leads to an enriched carbon, silicon and phosphorus content in the residue as compared with the original content of these elements in the cast iron. Sulphur is usually lost to some extent but when active sulphate-reducing bacteria are present, this loss is offset by the accumulation of ferrous sulphide in the residue with a consequent increase in the sulphur content of the residue out... 

Table 3.44 Increase in sulphur content of graphitic corrosion residue due to the presence of active sulphate-reducing bacteria...

The effect of sulphur from the gas phase is critically dependent on the effectiveness of fuel combustion. With good combustion to the limit of the available oxygen, and even down to 50% air deficiency, no serious effect was found from high-sulphur fuel in tests with 321S12 steel up to the usual limit of service temperature at 850°C, as shown in Table 7.9. With 310S24 steel at 1 100°C some effect from high sulphur content was found in 2 1 air gas with effective combustion, but none in 4 1 and 6 1 mixtures. 

Pfeiffer contends that, in undeoxidised nickel at least, the low sulphur contents normally found are insufficient to cause grain-boundary embrittlement and that the latter is, generally, due to intergranular oxides. In the presence of sulphur-containing gases, however, the level of sulphur required. 

Table 7.24 Corrosion resistance of nickel-chromium-iron alloys in oxidisng and reducing flue-gas atmospheres of varying sulphur content ...

Recently, attention has been directed to a study of the problem of grooving corrosion in line-pipe steel welded by high frequency induction or electric resistance welding. In sea water, it seems to be related to high sulphur content in the weld zone, the type of environment, its temperature and velocity The importance of sulphur is significant since Drodten and... 

Calcined petroleum coke breeze with a high fixed carbon content of 99% is used in deepwell applications. The material has a low particle size and, with suitable additives, may be converted into a slurry and pumped into a borehole. The sulphur content of this material is high (1 -4%), yet moisture (0-2%), ash (0-4%) and volatiles (0-4%) are low. The typical resistivity of this material is 0 -15 ohm m. 

Most cast irons, except those fully decarburised during malleabilising, give coatings of the chromium carbide type. In view of the great variations in composition of cast irons, reproducibility of results can be achieved only by careful control of specification. High phosphorus and sulphur contents are detrimental to the formation of non-porous coatings. 

Corrosion tests have also shown that there is a difference in the rates of corrosion throughout the year. This is partly because the sulphur content of the air is greater in winter than summer and partly because more of the... 

Calculate the volume of 5 per cent barium chloride solution which must be added from the approximate sulphur content of the iron pyrites FeS2 or of the mineral sulphide. 

Drastic oxidations of sulphoxides are used when analytical measurements of sulphur content are required. These methods usually lead to the formation of sulphate and occur via the formation of sulphones. These reactions will be discussed in Section III. 

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