摘要:

AbstractMethods of nitride production are summarised and their thermodynamics surveyed. Crystal structures and types of bonding in binary and ternary nitride compounds are classified and discussed. Kinetics of nitride formation are related to structural changes in the materials, which control diffusion of metals and nitrogen and cause nitride scaling. Metal nitridation with ammonia and nitride formation during ammonia synthesis are discussed.Information so far available on the sintering of nitrides and its effect on their chemical reactivity is reviewed. This effect is influenced by additives or impurities such as oxides formed by partial nitride hydrolysis and oxidation. Sintering and hot pressing increase the resistance of nitrides to hydrolysis and oxidation, so that they become more suitable for use as refractories. Often, corrosion resistance of nitride layers on metal surfaces is impaired by poor scaling resistance in air or oxygen at comparatively low temperatures. The kinetics and products of oxidation of nitrides so far studied, notably AlN, TiN and UN, depend mainly on the intrinsic reactivity of the material and the available surface at which oxidation can occur.Subsequent work will be concerned with changes in phase composition, surface area and crystallite and aggregate sizes and their correlation with production, sintering, hydrolysis and oxidation conditions for single and mixed nitrides. Suitable experimental techniques are summarised in this paper.

ISSN:0021-8871    

DOI:10.1002/jctb.5010180301

出版商:John Wiley&Sons, Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractSamples of calcium and magnesium nitrides have been prepared and hydrolysed ‘dry’ with water vapour and steam or ‘wet’ with liquid water. Changes in phase composition, surface area, crystallite and aggregate sizes have been correlated with hydrolysis conditions and compared with ‘dry’ and ‘wet’ hydration of lime and magnesia. The reactions involve the splitting of nitride and oxide crystallites and the subsequent ageing of the newly formed calcium and magnesium hydroxides.Hydrolysis of calcium cyanamide has been studied similarly. The intermediate product, hydrated lime, has been separately reacted with urea solutions and gives calcitic rhombs having a wide crystal

ISSN:0021-8871    

DOI:10.1002/jctb.5010180302

出版商:John Wiley&Sons, Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractThe preparation of the sulphur dichloride/oleic acid adduct in high yields is described.The reactivity of the chlorine atoms in the adduct in nucleophilic substitution reactions is demonstrated. Particularly noteworthy is the formation of a factice‐like polyester in almost quantitative yield when the adduct is heated with sodium hydroxide solution.Some derivatives of the adduct have been converted into polyamide

ISSN:0021-8871    

DOI:10.1002/jctb.5010180303

出版商:John Wiley&Sons, Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractPhase equilibrium data are presented foro‐ andp‐chlorotoluene distributed between n‐heptane and aq. methanol (95 vol.‐%), ‘Sulfolane’ and dimethyl sulphoxide (DMSO) and used to evaluate the possibility of employing distribution between these solvents as a means of separating a mixture of

ISSN:0021-8871    

DOI:10.1002/jctb.5010180304

出版商:John Wiley&Sons, Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractA radioactive tracer technique has been devised to measure the permeability of thick membranes and layers of synthetic rubbers and glass‐fibre laminates to liquefied hydrocarbons. The technique involves the use of the tritium‐labelled hydrocarbon, prepared by treating the appropriate Grignard reagent with tritiated water. The labelled hydrocarbon is transferred to a thermostatted permeability cell. Permeate is trapped in a vial which contains liquid scintillation phosphor and is cooled in liquid air. The trapped permeate is measured by liquid scintillation counting of the sealed vial. Such measurements, made over an appropriate period, allow permeability constants to be calculated.Propane transfer rates down to 10−10g/h have been measured, with membranes of thickness ranging from about 0·5 to 1·5 mm, giving permeability constants of the order of 10−11g cm−1h−1atm−1. Abnormal rate/time curves have been found for some membranes.Factors affecting the accuracy of the measurements, and the safety precautions necessary, are discussed. Finally, extension of the technique to the study of hydrocarbons of low boiling point such as methan

ISSN:0021-8871    

DOI:10.1002/jctb.5010180305

出版商:John Wiley&Sons, Ltd    

年代:1968

数据来源: WILEY