Sulphide melt

Andersen T., Griffin W. L., and O Reilly S. Y. (1987) Primary sulphide melt inclusions in mantle-derived megacrysts and pyroxenites. Lithos 20, 279—295. 

Oversby V. M. and Ringwood A. E. (1972) Partitioning of potassium between silicates and sulphide melts experiments relevant to the Earth s core. Phys. Earth Planet. Inter. 6, 161-166. 

Di-a-naphthylarsenious sulphide, (CioH7)a-A sS, is formed either by the interaction of magnesium a-naphthyl bromide and arsenic trisulphide, or by treating the corresponding oxide or chloride with hydrogen sulphide in the usual way. The sulphide melts at 185° to 186° C. 

In summary, the elements Cu and Zn may be quite mobile during metamorphism and alteration and concentrations may diverge from expected smooth patterns. Anomalies in Ni and Cr concentrations may reflect the role of olivine (Ni) and clinopyroxene or spinel (Cr). Ni and Cu can also be concentrated into sulphide melts. Ti anomalies indicate the role of Fe-Ti oxides. 

These equations provide the basis for the mathematical analysis of the polarisation curves. Such analysis was carried out to gain some important information on the properties and the behaviour of sulphide melts ionic and electronic conductivities the efficiency of electrolytic decomposition and its dependence on electrolysis conditions the values of the stationary voltage and dissolution rate of electrolysis products after the current cut-off. 

The parameter 8 which we can see in Eq. (5.2) can be interpreted as one-half of the effective thickness of the sample if the sample is solid and if the stationary distribution of the charge carriers has already been established. In case of a melt where convective mixing in the bulk occurs, the value 5 should correspond to the thickness of the diffusive layer where mixing is absent. The exact value of 5 in sulphide melts at free convection conditions was not a subject of experimental investigatirms the order of value about 10 cm can be estimated from hydrodynamic considerations. That is why we are not able to extract the precise value of xj from the data on limiting electron currents ioo-... 

Phosphorus sulphide melts with low P/S ratios contain mainly the established cage molecules indicated in Figure 4.12, but with high sulphur contents long-chain polymers are also present. An insoluble yellow powder of composition (PS) can be made by reacting magnesium with thiophos-phoryl bromide [16,17]. 

The thermal and electrochemical corrosion of stainless steel in the S/polysulphide melt has been reported previously. Thermal corrosion gives rise to an adherent, black sulphide deposit on the surface of the steel, but electrolytic corrosion is essentially a stripping process with the stainless steel cell body being progressively dissolved in the sulphide melt. Electrochemical experiments have revealed that this occurs predominantly during the final stages of discharge and is associated with polarisation of the melt and the formation of Na S close to the steel surface. 

L.J. Wang, K.C. Chou and S. Seetharaman, A comparison of traditional geometrical models and mass triangle model in calculating the surface tensions of ternary sulphide melts Calphad, 32(2008), 49-55. 

PPha, pyridine) organic groups (olefines, aromatic derivatives) and also form other derivatives, e.g. halides, hydrides, sulphides, metal cluster compounds Compounds containing clusters of metal atoms linked together by covalent (or co-ordinate) bands, metaldehyde, (C2H40) ( = 4 or 6). A solid crystalline substance, sublimes without melting at I12 1I5" C stable when pure it is readily formed when elhanal is left in the presence of a catalyst at low temperatures, but has unpredictable stability and will revert to the monomer, ft is used for slug control and as a fuel. 

The sulphides (I) can be readily oxidised in glacial acetic acid solution by potassium permanganate to the corresponding sulphones (II) the latter exhibit a wide range of melting points and are therefore particularly valuable for the characterisation of mercaptans ... 

The presence of the either linkages is sufficient to allow the material to be melt processed, whilst the polymer retains many of the desirable characteristics of polyimides. As a consequence the material has gained rapid acceptance as a high-temperature engineering thermoplastics material competitive with the poly-sulphones, poly(phenylene sulphides) and polyketones. They exhibit the following key characteristics ... 

Crystallisable polymers have also been prepared from diphenylol compounds containing sulphur or oxygen atoms or both between the aromatic rings. Of these the polycarbonates from di-(4-hydroxyphenyl)ether and from di-(4-hydroxy-phenyl)sulphide crystallise sufficiently to form opaque products. Both materials are insoluble in the usual solvents. The diphenyl sulphide polymer also has excellent resistance to hydrolysing agents and very low water absorption. Schnell" quotes a water absorption of only 0.09% for a sample at 90% relative humidity and 250°C. Both the sulphide and ether polymers have melting ranges of about 220-240°C. The di-(4-hydroxyphenyl)sulphoxide and the di-(4-hydroxy-phenyl)sulphone yield hydrolysable polymers but whereas the polymer from the former is soluble in common solvents the latter is insoluble. 

As with the polysulphones, the deactivated aromatic nature of the polymer leads to a high degree of oxidative stability, with an indicated UL Temperature Index in excess of 250°C for PEEKK. The only other melt-processable polymers in the same league are poly(phenylene sulphides) and certain liquid crystal polyesters (see Chapter 25). 

Sulphates, which form part of the ash from the combustion of many fuels, are not harmful to high-alloy steels, but can become so if reduction to sulphide occurs. This leads to the formation of low melting point oxide-sulphide mixtures and to sulphide penetration of the metal. Such reduction is particularly easy if the sulphate can form a mixture of low melting point with some other substance. Reduction can be brought about by bad combustion, as demonstrated by Sykes and Shirley , and it is obviously important to avoid contact with inefficiently burnt fuels when sulphate deposits may be present. Reduction can also be brought about in atmospheres other than reducing ones and the presence of chlorides or vanadium pentoxide has been shown to be sufficient to initiate the reaction. It has also been shown that it can be initiated by prior cathodic polarisation in fused sodium sulphate. The effect of even small amounts of chloride on oxidation in the presence of sulphate is illustrated in Fig. 7.33 . 

Although iron sulphide also forms a eutectic with the metal this melts at 988°C, and at temperatures in the region of 700 to 800°C alloys with substantial proportions of nickel replaced by iron and a chromium level maintained at about 20% show advantages over nickel-chromium-base alloys in resistance to sulphur attack. 

Kassner used a rotating disc, for which the hydrodynamic conditions are well defined, to study the dissolution kinetics of Type 304 stainless steel in liquid Bi-Sn eutectic. He established a temperature and velocity dependence of the dissolution rate that was consistent with liquid diffusion control with a transition to reaction control at 860 C when the speed of the disc was increased. The rotating disc technique has also been used to investigate the corrosion stability of both alloy and stainless steels in molten iron sulphide and a copper/65% calcium melt at 1220 C . The dissolution rate of the steels tested was two orders of magnitude higher in the molten sulphide than in the metal melt. 

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