摘要:

AbstractAfter dynamic and static experiments on the mechanical behaviour of bitumens an attempt was made to incorporate all the essential factors into a simple system. This was found to be possible in the form of a nomograph, by means of which the deformation of bitumens can be calculated as a function of stress, time and temperature. Origin or method of manufacture proved to be of less importance than hardness and rheological type. For correlation with standard test‐methods, the ring‐and‐ball temperature and the penetration index were found to be suitable parameters. The nomograph enables the average behaviour of a given grade to be calculated with an accuracy sufficient for engineering purposes.Another feature of the nomograph is that it creates the possibility of giving an interpretation of other routine tests. By way of example both penetration and Fraass breaking test are disc

ISSN:0021-8871    

DOI:10.1002/jctb.5010040501

出版商:John Wiley&Sons, Ltd    

年代:1954

数据来源: WILEY

摘要:

AbstractIn electrolytic tinplate the tin‐iron alloy layer, formed during the flow‐brightening operation, may range in thickness from approximately 1·5 to 8 μin. Refined methods of determination are thus necessary. Four procedures have been studied and compared. Gravimetric methods, involving determination of the free‐tin (unalloyed) and alloy layers either separately, or simultaneously as the total coating, appear to be sufficiently accurate and trustworthy provided that a large enough sample‐area is available. A ‘coulometer’ method, involving measurement of the quantity of electricity required to dissolve the coating anodically in dilute hydrochloric acid, was found to be most suitable for rapid routine determinations on relatively small specimens for which gravimetric or volumetric methods would be inappropriate.It has been confirmed, by chemical andX‐ray examinations, that the tin‐iron alloy layer in flow‐brightened electrolytic tinplate is the intermeta

ISSN:0021-8871    

DOI:10.1002/jctb.5010040502

出版商:John Wiley&Sons, Ltd    

年代:1954

数据来源: WILEY

摘要:

AbstractBrief descriptions are given of an automatic distillation apparatus for performing Engler distillations, a recording viscometer for oils and grease, a flash‐point recorder, a recording colorimeter, a detector for water in acetone, and a tester for indicating inhomogeneity in blending vessels. The use of such instruments in petroleum refineries illustrates the growing need for faster and more accurate measurement of product qualit

ISSN:0021-8871    

DOI:10.1002/jctb.5010040503

出版商:John Wiley&Sons, Ltd    

年代:1954

数据来源: WILEY

摘要:

AbstractIt is shown that there are three components in a mixing process: convection, diffusion and shear. The concepts involved in analysing complete and partial mixtures are examined and a statistically satisfactory expression evolved for the state of a mixture. A number of theories of mixing rate are examined and compared with the few published experimental results, and a new theoretical treatment is offered based on diffusion theory. This is shown to be in at least as good agreement with fact as existing theories, and to provide a better basis for extension to more complex cases.

ISSN:0021-8871    

DOI:10.1002/jctb.5010040504

出版商:John Wiley&Sons, Ltd    

年代:1954

数据来源: WILEY

摘要:

AbstractAs a part of a broad programme of investigation of sodium hydroxide, the transitions up to its melting point were studied. This was accomplished by correlation of results obtained through use of differential thermal, high‐temperature microscopic, and high‐temperatureX‐ray analyses. The melting of sodium hydroxide monohydrate, the driving off of entrapped water at higher temperatures, the transition ofx‐sodium hydroxide to β‐sodium hydroxide, and the melting point of β‐sodium hydroxide were the transitions identified and studied. AnX‐ray powder pattern for β‐sodium hydroxide was obtained; it appeared to indicate a cubic structure for this material, with a lattice p

ISSN:0021-8871    

DOI:10.1002/jctb.5010040505

出版商:John Wiley&Sons, Ltd    

年代:1954

数据来源: WILEY

摘要:

AbstractThe rates of corrosion obtained when testing stainless steels in concentrated boiling nitric acid can be very markedly affected by the method of testing. The main source of error is the contamination of the test acid by the dissolved steel. If the acid can be maintained in an essentially pure state, corrosion is linear with time, but, if corrosion products are allowed to accumulate, acceleration of attack occurs, and thus the volume of acid used for testing has a serious effect on the rates of attack obtained.The prime cause of this acceleration is the chromium dissolved in the acid. This affects the rate of corrosion only if it is in the sexivalent state, and the degree of acceleration is roughly proportional to the amount of dissolved chromium in this condition. Chromium can be oxidized from the terto the sexi‐valent state by boiling concentrated nitric acid, but the extent to which this reaction proceeds is affected by several factors, which can consequently have a marked effect on the rate of corrosion of the steel. These include the type of condenser used and the strength of the test acid. Cyclic tests, in which the acid is changed at regular intervals, are not necessarily the answer to errors introduced by this process, as the mechanism of attack in sexivalent chromium‐bearing nitric acid is such that the stainless steel is left in a condition susceptible to heavier attack, even in pure nitric acid, and this can lead to earlier serious contamination of the acid used in later cycles. Unless these factors are taken into account when designing testing procedures, less satisfactory materials may be selected, since the steels most resistant to pure nitric acid are not necessarily those most resistant to nitric acid contaminated with sexivalent chrom

ISSN:0021-8871    

DOI:10.1002/jctb.5010040506

出版商:John Wiley&Sons, Ltd    

年代:1954

数据来源: WILEY

摘要:

AbstractA practical method for producingO‐methylurea hydrochloride on a laboratory scale by methylation of urea is described in detai

ISSN:0021-8871    

DOI:10.1002/jctb.5010040507

出版商:John Wiley&Sons, Ltd    

年代:1954

数据来源: WILEY