摘要:

AbstractAdhesion has become an increasing problem on railways. Work is described in which the effects of certain esters on the coefficient of friction were measured with apparatus designed to simulate wheel‐rail conditions. The results are reported and discusse

ISSN:0375-9210    

DOI:10.1002/jctb.5020210901

出版商:John Wiley&Sons, Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractFollowing the occurrence of fires in chemically activated carbon in transit, a study has been made of the self‐heating and ignition properties of this material.Thermal ignition theory has been applied to the results of laboratory scale self‐ignition experiments and has enabled realistic prediction of critical sizes of pile for self‐heating to ignition at ordinary ambient temperatures. However, predictions of times to ignition at ordinary temperatures are much larger than found in practice.A distinction emerges between a long‐term self‐heating process responsible for the observed ignition of the ‘weathered’ carbon and short‐term processes which probably include the establishment of moisture equilibrium with the atmosphere and which are largely completed during the standard ‘weathering’ time of 8 days. The long‐term process is not affected by this weathering but is dependent on the temperature of carbonisation and weathering at elevated temperatures (e.g. 100°C).Safe carriage of the carbon in economically worthwhile quantities is ensured by packing in polyethylene bags. These can sustain a small amount o

ISSN:0375-9210    

DOI:10.1002/jctb.5020210902

出版商:John Wiley&Sons, Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractGilsonite pitch and polyvinyl chloride (PVC) were carbonised at slow rates of 0.5°c min−1and the products of carbonisation examined by chromatography, mass spectrometry, nuclear magnetic resonance spectroscopy, optical microscopy, scanning electron microscopy and electron spin resonance spectroscopy. The original Gilsonite pitch contains ∼ 5% of aromatic protons, rising to 24% in soluble material just prior to formation of the graphitisable semi‐coke at 410°c. The carbonised PVC melts (389°c) to form a black isotropic liquid with 23% aromatic protons, rising to 41% at the onset of the coalescence of the mesophase spheres (420–440°c). The constituent molecules are considered to be hydrogenated cyclic structures possessing a great variety of saturated and unsaturated side‐groups. During carbonisation, there is loss of side‐groups, but it is the essentially aliphatic cyclic structures which co‐condense to form the mesophase. Further aromatisation must occur within the mesophase and semi‐coke. The presence of heteroatoms within the Gilsonite pitch is considered to restrict the growth of the mesophase structures and their ability to coalesce to form the much larger units of anisotropic character observed in the case of PVC. Electron spin resonance spectroscopy suggests that free radicals are not necessary to form the mesophase, the free radical character being developed after formation of the mesophase, probably as the aroma

ISSN:0375-9210    

DOI:10.1002/jctb.5020210903

出版商:John Wiley&Sons, Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractFurther studies were carried out on the reversible phase transformation of the low melting (1228°c) calcium chromate chromite (941) into the high melting (2170°c) monocalcium chromite (CK) with the liberation of free CaO and oxygen.The investigation of specimens of synthesised 941, calcium chomate (CK1), and 941‐bearing samples with a high content of periclase (as in dolomitic magnesite chrome refractories) cooled from different temperatures showed the presence of transformation products of 941 phase under different conditions of its formation, and thermogravimetric analysis and complex differential thermal analysis confirmed the reversible nature of this phase transformation.Irrespective to the method of formation of 941 or the existence of a high periclase content and a solid solution of 2CaO.SiO2with it, 941, at its melting point, starts to undergo a reversible phase transformation according to the equation: 9CaO.4CrO3.Cr2O3.3CaO.Cr2O3+6CaO+3 O2.The presence of 941 phase in basic refractories produced from raw materials with a high CaO content, should be considered to be a secondary phase, re‐formed during the cooling process.Beta‐alpha polymorphism of the liberated CK was exhibited above 1600°c during this phase transf

ISSN:0375-9210    

DOI:10.1002/jctb.5020210904

出版商:John Wiley&Sons, Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractMother liquor compositions during the solar evaporation of marine bitterns have been compared with corresponding isothermal equilibria in the NaCl‐KCl‐MgCl2‐MgSO4‐H2O system. The compositions indicate that on solar evaporation of bitterns, potassium is deposited solely in the form of kainite, and that co‐deposition of free sylvite and epsomite does not take place. It is also shown that during solar evaporation, the concentration of potassium is relatively low and that of magnesium relatively high, resulting in a more efficient precipitation of potassium in solar evaporation than in the forced or isothermal evaporation of sea water or of p

ISSN:0375-9210    

DOI:10.1002/jctb.5020210905

出版商:John Wiley&Sons, Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractPotassium is deposited as kainite and/or carnallite by solar evaporation of sea and inland bitterns, respectively. The solubility of this natural kainite in water was found to be at 20 g magnesium chloride per 100 g water as against at 27.5 g obtained with synthetic kainite. As a result, the equilibrium data available from conventional phase diagrams were found to be not applicable for the conversion of kainite to potassium schoenite, an intermediate product to obtain potassium sulphate. Therefore applicability of the system K2Cl2‐MgSO4‐H2O to natural kainite was investigated and equilibria in reactions in slurries and optimum yields were worked

ISSN:0375-9210    

DOI:10.1002/jctb.5020210906

出版商:John Wiley&Sons, Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractA simple sampling system was developed to enable the sampling of liquid oxygen, nitrogen and argon in the plant, which can then be analysed at any remote laboratory. The procedure is described for the operation of the high pressure system to avoid contamination by air. Analyses have shown that repetitive sampling of the same product tank gave repeatable results.

ISSN:0375-9210    

DOI:10.1002/jctb.5020210907

出版商:John Wiley&Sons, Ltd    

年代:1971

数据来源: WILEY

ISSN:0375-9210    

DOI:10.1002/jctb.5020210908

出版商:John Wiley&Sons, Ltd    

年代:1971

数据来源: WILEY