Sulphur in copper

Sulphur has a negative effect on the conductivity of unalloyed copper and - just like oxygen - causes at higher temperatures in an hydrogen atmosphere the formation of pores resulting in a decrease in strength. The latter is also valid for some copper alloys. Moreover, sulphur has a negative effect on the corrosion resistance of copper. 

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THE DETERT INATION OF PHOSPHORUS (AND SULPHUR) IN COPPER AND NICKEL... 

Table VIII-4 gives some results for phosphorus and sulphur in copper of different degrees of purity.

Pugh and Watermann (6) mention another type of the sulphur dioxide titration and determine sulphur in copper by a procedure in which the sample is heated at about 1150°C in oxygen. Oxides of sulphur in the evolved gas are determined in several ways, e.g. by titration with a standard borate solution. Such methods are satisfactory, provided that standard samples of known sulphur content are available, and the sulphur content of the sample is above 50 g/g. 

This method can be applied for the determination of 1 to 50 Mg/g sulphur in copper alloys its reliability is estimated at 20 %. 

Based on the reaction between sulphides and hydrogen at higher temperatures, a method for the determination of sulphur in copper has been elaborated by Watson et al. (15). The sample is placed in a porcelain or alumina boat and introduced into a quartz tube, heated at 1100 to 1150°C by a resistance furnace and through which flows a stream of ultrapure hydrogen. Hydrogen sulphide released by the hot and/or molten metal is carried by the gas stream and absorbed by a sodium hydroxide solution. Fig. XI-4 shows the apparatus used. 

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. 

Vandecasteele et al. (22) describe the determination of sulphur in copper and nickel. 

Corrosion by sulphur additives Sulphur compounds occur naturally in most lubricants and many oil additives contain sulphur. In a properly formulated lubricant these sulphur compounds should be inactive at ambient temperature. At elevated temperatures they may decompose to give more active materials which can stain and corrode metals, particularly silver and copper. However, these same sulphur compounds have many beneficial qualities this is why they are not removed com.pletely in refining and why they are used as additives. 

A limited degree of control over the corrosivity of the product packed is possible. Minor pH adjustments may be helpful, especially in ensuring an anodic relation of tin to steel corrosion promoters, like nitrate, sulphur and copper may be excluded from necessary additives, such as water and sugar, and from sprays applied to crops approaching harvest. The effect of sulphur compounds which may remain from spray residues is complex but often includes reversal of the tin-iron polarity. 

Austenitic stainless steels-determination of resistance to intergranular corrosion. Part 1 Corrosion test in nitric acid medium by measurement of loss of mass (Huey test) Austenitic stainless steels-determination of resistance to intergranular corrosion. Part 2 Corrosion test in a sulphuric acid/copper sulphate medium in the presence of copper turnings (Moneypenny Strauss test)... 

Procedure (copper in copper(I) chloride). Prepare an ammonium iron(III) sulphate solution by dissolving 10.0 g of the salt in about 80 mL of 3 M sulphuric acid and dilute to 100 mL with acid of the same strength. Weigh out accurately about 0.3 g of the sample of copper(I) chloride into a dry 250 mL conical flask and add 25.0 mL of the iron(III) solution. Swirl the contents of the flask until the copper(I) chloride dissolves, add a drop or two of ferroin indicator, and titrate with standard 0.1 M cerium(IV) sulphate. 

Allen, J.D. and J.M. Gawthome. 1987. Involvement of the solid phase of rumen digesta in the interaction between copper, molybdenum and sulphur in sheep. Brit. Jour. Nutr. 58 265-276. 

Froslie, A., G. Norheim, and N.E. Soli. 1983. Levels of copper, molybdenum, zinc, and sulphur in concentrates and mineral feeding stuffs in relation to chronic copper poisoning in sheep in Norway. ActaAgric. Scand. 33 261-267. 

The ammine crystallises in hexagonal plates which are colourless, readily oxidised in air, insoluble in alcohol, and decomposed by water. It is stable up to 100° C., but above that temperature loses ammonia, liberating Cu2S04, which then decomposes. The salt reduces nitric acid, and is broken down by dilute sulphuric acid, copper being precipitated and cupric ammonium sulphate formed. 

A variety of pyrites, known in the trade as Spanish pyrites, lias cf late been much employed. This is much richer in copper than the Wicklow species. On the introduction of this mineral, it was usual for the sulphuric acid manufacturer to engage to return tha... 

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