摘要:

AbstractA distinction is made between the electrochemical corrosion of metallic aluminium, in which aluminium oxide is formed, and the chemical solution of the aluminium oxide, leading eventually to the interaction of aluminium ions with the stannic acid stabiliser. The electrochemical reaction is facilitated by chloride ions and retarded by nitrate ions, whilst the chemical solution is enhanced by hydrogen ions and the presence of stannic acid sol. Only the chemical reaction affects the stability of the stannic acid stabiliser.

ISSN:0021-8871    

DOI:10.1002/jctb.5010111101

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractRadio‐isotope exchange at 25°, using45Ca, between calcium silicate hydrate and its aqueous solution, has established that an initial rapid exchange involving between 12 and 20% of the calcium in the calcium silicate hydrate crystals, is followed by a slow, diffusion‐controlled exchange, tentative self‐diffusion coefficient for calcium increasing from 1.08 × 10−23cm.2sec.−1to 60.7 × 10−23cm.2sec.−1as the composition changes from 0.36CaO,SiO2,aq. to 1.39CaO,SiO2,aq. The low mobilities of the calcium ion indicated from these results account for the slowness with which calcium silicate hydrate comes to equilibrium with its aqueous solution and also help to explain the high durability of Portland cement products subjected to l

ISSN:0021-8871    

DOI:10.1002/jctb.5010111102

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractThe effects were studied of some retarders and accelerators on the kinetics of hydration of samples of six calcined gypsums with different characteristics. The samples showed considerable individuality in their response, some being virtually unaffected by amounts of retarder or accelerator that markedly affected the hydration of others. The effects described are discussed in terms of theories already developed for the actions of retarders and accelerators.

ISSN:0021-8871    

DOI:10.1002/jctb.5010111103

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractThe effects were studied of some retarder‐accelerator mixtures on the kinetics of setting of samples of seven calcined gypsums with different characteristics. Egg albumin, calcium acetate, sodium hexametaphosphate and borax were the retarders used in conjunction with precipitated calcium sulphate, potassium sulphate and sodium chloride as accelerators. Some of the retarder‐accelerator mixtures reduced the range of the induction periods of the samples, the most effective being those based on calcium acetate as a retarder and precipitated calcium sulphate as accelerator the least effective were those based on borax as retarder and potassium sulphate as accelerator.The effects were tested of the retarder‐accelerator mixtures in reducing the sensitivity of plaster to contamination with retarders and accelerators. All the formulations except sodium hexameta‐phosphate and borax with potassium sulphate reduced the difference between the retarded induction period and the accelerated induction period.The observations made are discussed in terms of the theories already developed for the actions of retarders and accel

ISSN:0021-8871    

DOI:10.1002/jctb.5010111104

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractIn tests conducted with air containing known concentrations of acetic acid vapour and moisture, it was found that very small amounts of acetic acid (0.5 p.p.m. or less) can promote corrosion of metals at moisture levels of 80% R.H. and above. The type of corrosion product varies with the concentration of acetic acid and moisture. A number of common metals are affected, but aluminium is relatively resistant, and tin is outstandingly so. With metals exposed to vapours from damp wood, corrosion is markedly promoted when the wood has previously been heated in kiln‐drying after rot‐proofing treatment with aqueous soluti

ISSN:0021-8871    

DOI:10.1002/jctb.5010111105

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractStannic acid sols in concentrated hydrogen peroxide differ greatly in appearance and behaviour from stannic acid hydrosols. In water the sol particles are comparatively large, grow rapidly and are of a feathery appearance, whilst in hydrogen peroxide the particles are small, compact and show a distinct but much less pronounced tendency to increase in size with time. This ageing process in hydrogen peroxide, which apparently consists of the aggregation of the smaller particles in a polydisperse system, takes place mainly during the first week after preparation and results in a reduction of approximately 25% in the adsorptive power of the sol.

ISSN:0021-8871    

DOI:10.1002/jctb.5010111106

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractThe heat of dehydration of clays caused by the loss of combined water between 425 and 750° accounts for nearly 10% of the total heat input in estimating the thermal efficiency of kiins used for the production of structural clay products. Heat of dehydration is usually assessed from a determination of the ‘ residual ignition loss’, using certain assumptions. This paper discusses the possibility of applying Differential Thermal Analysis to calculate directly the heats of dehydration of brick clays, potassium sulphate being used as a stan

ISSN:0021-8871    

DOI:10.1002/jctb.5010111107

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY