Melting points compound formation

Phase relations in an isothermal section at 1070K were determined by Haschke et al. (1966) by means of X-ray powder diffraction methods (fig. 20). Samples were synthesized by heating compacted mixtures of 99.9 mass% purity for a few minutes in an induction furnace slightly above the melting point. The formation of two complete solid solutions was reported Ce(Si,Ge) and Ce(Si,Ge)2 x. No ternary compounds were observed. 

The Group 4—6 carbides are thermodynamically very stable, exhibiting high heats of formation, great hardness, elevated melting points, and resistance to hydrolysis by weak acids. At the same time, these compounds have values of electrical conductivity. Hall coefficients, magnetic susceptibiUty, and heat capacity in the range of metals (7). 

Excess sodium hydroxide present can also be troublesome as the alkali reacts with the SO3 present in the gas stream to form a range of alkali sulfates which in themselves are highly corrosive to metallic components. In addition, the combination of alkali sulfate -l- V2O5 can result in compounds having melting points as low as 600°E. This situation is only encountered when alkali is present in amounts in excess of that which can react stoichiometrically with V2O5, since the formation of alkali vanadates is favored over that of alkali sulfates. 

A mixture of 12.6 g of benzoyl chloride in 100 cc of ethylene chloride is added dropwise to a suspension of 25.6 g of 3ethylene chloride and 21.8 g of triethylamine within 18 minutes at room temperature while stirring. The mixture is stirred at room temperature for a further 14 hours, 200 cc of water are added, the organic phase is separated and concentrated to an oil in a vacuum. Upon adding ether/dimethoxy ethane to this oil, crude 6-ben zoy I-3absolute ethanol with the addition of a small amount of coal, the compound has a melting point of 125°C to 127°C (decomp.). Displacement of the halogen with hydrazine leads to the formation of endralazine. 

If the major constituents of a solid alloy in contact with a liquid alloy are highly soluble in the latter without formation of compounds, progressive attack by solution is to be expected. If, on the other hand, a stable inter-metallic compound is formed, having a melting point above the temperature of reaction, a layer of this compound will form at the interface and reduce the rate of attack to a level controlled by diffusion processes in the solid state. By far the most serious attack, however, occurs in the presence of stresses, since in this case the liquid alloy, or a product of its reaction with the solid alloy, may penetrate along the grain boundaries, with resultant embrittlement and serious loss of strength. 

Reactions of contaminants in the fuel or air in the combustion zone can result in the formation of compounds which can condense as molten salts onto cooler components in the system. This type of process can occur when fuels containing sulphur or vanadium are burnt. In the case of sulphur contaminants, alkali sulphates form by reactions with sodium which may also be present in the fuel or in the combustion air, and for vanadium-containing fuels low-melting-point sodium vanadates or vanadium pentoxide are produced, particularly when burning residual oils high in vanadium. Attack by molten salts has many features in common which will be illustrated for the alkali-sulphate-induced attack, but which will be subsequently shown to be relevant to the case of vanadate attack. 

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