摘要:

AbstractA sample of Florida kaolin was separated by a supercentrif uge into three nearly mono‐disperse systems whose sizes were, respectively, 0.1 to 0.2, 0.2 to 0.4, and 0.4 to 1.0 micron. These samples were electrodialyzed, and to aliquot samples of the H clay thus obtained, varying concentrations of sodium or barium hydroxide were added.The base‐exchange capacity at pH 7 varied linearly with the surface area. The apparent viscosity was reduced to about 4% of its original value by the addition of 1 milli‐equivalent of sodium hydroxide, after which further additions had a very slight lowering effect. The addition of electrolyte decreased the yield point and increased the maximum strain before rupture at the water content of optimum plasticity. The water of plasticity, pore water, shrinkage water, and film thickness were decreased by adding electrolyte. The dry transverse strength was doubled by the change from H clay to Na clay. Most properties varied linearly with the surface area within the experimental error. The potential concept of plasticity is briefly out

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1940.tb14196.x

出版商:Blackwell Publishing Ltd    

年代:1940

数据来源: WILEY

摘要:

AbstractTorsion properties of a plastic fire clay, a ball clay, two flint fire clays, a bentonite, and Georgia kaolin were studied. The effect of exchangeable bases on the surface of the clay particles on stress‐strain relationships was established. The widest differences, in general, were found in the sodium and hydrogen forms of the various bodies. A rational explanation of the behavior of clays with different exchangeable bases lies in the fact that their colloidal natures govern to a large degree their workable characteristics, and colloidal properties, in turn, are dependent on the water film surrounding the particle. The nature of the water film is influenced by the kind and the nature of the charges in the ion atmosphere surrounding the particles and may be changed by replacing an exchangeable base with another catio

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1940.tb14197.x

出版商:Blackwell Publishing Ltd    

年代:1940

数据来源: WILEY

摘要:

AbstractThe absorption and transverse strength of clay bodies, both in the fired and unfired state, are influenced greatly by the nature of the exchangeable bases present on the surface of the clay particles. Plastic clays with high exchange capacity are more affected than nonplastic clays, such as flint clays. Of the various common base forms studied, sodium‐type clays in general require less water to give the same degree of stiffness, and their fired and unfired transverse strengths are high. Hydrogen clays require higher water content and have greater porosity and lower transverse strength. Data are given on a plastic fire clay, a ball clay, a bentonite, and two flint fire clays. All experiments made were on stiff‐mud bod

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1940.tb14198.x

出版商:Blackwell Publishing Ltd    

年代:1940

数据来源: WILEY

摘要:

AbstractStudies were made at 100°F. and 50% relative humidity, 150°F. and 50% humidity, and 175°F. and 15% humidity to determine the effect of exchangeable bases present on the surface of the clay particles on drying rates. Drying may be considered to take place in two stages which are characterized by different rates. The first is rapid and is accompanied by shrinkage of the body, whereas the second is considerably slower and the shrinkage is slight. The drying rates of the base‐saturated bodies studied were nearly the same in the first stage, but in the second pronounced differences resulted. Sodium clays dried much more slowly than the other bodies investigated. At 175°F. and 15% humidity, H clay dried the most rapidly. A rational explanation of the phenomena, based on the colloidal nature of the clay particle and on the unfired absorption of the bodies, is

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1940.tb14199.x

出版商:Blackwell Publishing Ltd    

年代:1940

数据来源: WILEY

摘要:

AbstractA brief history of glaze literature on coefficient of expansion and a short description of methods of determination are given. Using the factors of Mayer and Havas to calculate the coefficient of expansion of glazes from the percentage weights of their oxides, factors were calculated for glaze raw materials. Instead of the empirical formulas for raw materials, chemical analyses supplied by dealers of glaze materials were used. A series of glazes, starting with a high coefficient and gradually decreasing in coefficient, was tested. After determining from this series the calculated coefficient of the noncrazing glaze, a series was made in which the composition was varied and the coefficient was kept constant. Glazes of low coefficient did not craze. No crazing resulted when the composition of the glazes was varied and the calculated coefficient was kept constant. This method is a valuable means of controlling crazing in sanitary glazes because of its simplicity, the economy of experimental equipment, and the relatively short time required to complete the tests.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1940.tb14200.x

出版商:Blackwell Publishing Ltd    

年代:1940

数据来源: WILEY