摘要:

AbstractThermal and moisture expansion determinations were made on ten ball clays of the Kentucky, Tennessee, and English types alone and on typical semivitreous and vitreous bodies in which each of these ball clays was incorporated. The clays and bodies were fired at cones 6, 9, and 11. The data indicate that the ball clays fall into five distinct groups. Although none of the clays showed a direct relation between its expansion and that of the bodies in which it was incorporated, a majority possessed characteristics sufficiently similar to permit their classification into groups in which the behavior of the clays alone is indicative of their influence on the bodies. When several ball clays were jointly incorporated into bodies, they showed additive thermal and moisture expansion values.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1943.tb15207.x

出版商:Blackwell Publishing Ltd    

年代:1943

数据来源: WILEY

摘要:

AbstractA method of analysis has been developed that gives consistent results for soluble sulfate and total soluble salts in ceramic raw materials and bodies. Values for sulfate on a dry‐weight basis ranged from 0.01 to 0.28% with ball clays, from 0.002 to 0.015% with china clays, and from 0.000 to 0.007% with miscellaneous raw materials. Bentonites were relatively high in sulfate, a Wyoming bentonite showing the highest value, 0.194%.The distribution of sulfate in the slip, cake, and press water was determined for eighteen ceramic bodies. An increase in the water‐clay ratio in slips was found to increase the recoverable soluble sulfate (percentage dry basis). In experiments on repeated cycles of cake to slip to filter pressing, soluble sulfate continued to be released, but the bulk of the sulfate was obtained in the first pressing. Quantitative results are given on the effectiveness of barium carbonate as a precipitating reagent for sulfate in slips.Aging from six months to one year was found to have little effect on the soluble sulfate in stored samples of slips, cakes, and press waters. Dry storage, however, doubled the soluble sulfate content of a freshly mined ball clay within six months, evidently by oxidation of sulfur compou

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1943.tb15208.x

出版商:Blackwell Publishing Ltd    

年代:1943

数据来源: WILEY

摘要:

AbstractFive types of electrodes and arcing techniques were compared. Complete qualitative analyses offour clays were run, and a quantitative method has been set up for trace elements, giving a short method for sample preparation. Two elements were determined quantitatively to show the described procedure.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1943.tb15209.x

出版商:Blackwell Publishing Ltd    

年代:1943

数据来源: WILEY

摘要:

AbstractEvidence for the existence of a “transformation region” rather than a “transformation point” in the 1014poise range of glasses has been produced by a variety of experiments, both static and dynamic. Refractive index was measured (1) on small specimens quenched in air and (2) directly in the furnace by the single‐prism and three‐prism methods. Quantitative agreement was obtained, and the method of quenched samples is recommended as the simplest of those tested. Thermal expansion coefficients were also determined on the quenched samples.Disannealing lowered the refractive index of glasses; for a borosilicate crown, by an order of 0.006. The change resulting from strains was comparatively small and in the opposite direction so that birefringence was found to be an untrustworthy indicator of the state of a glass. For a series of optical glasses, the difference between the refractive‐index extremes is a function of the lowest temperature at which the minimum index can be realized. Thermal expansion coefficients may also vary with heat‐treatment. Two limiting states of glass are postulated to explain the observations. In between these states lies the region of transformation, including an intermediate state for each temperature between the two limiting temperatures. For all of the glasses e‐xamined, the extent of the transformation region was about 100°C. The rate of transformation into the low‐temperature state may be studied from “equilibrium curves” by plotting stable refractive index as a function ‐of temperature. Whereas the conversion to the high‐temperature state is instantaneous at the upper temperature of the transformation region, the conversion to the low‐temperature condition demands a minimum time at each temperature, which explains why annealing is such a time‐consuming process. The annealing time, however, may be drastically reduced by following the equilibrium curves in a stepwise fashion. With insufficient annealing, higher temperature states are frozen in and transformation continues even at room temperature as proved by measurements extend

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1943.tb15210.x

出版商:Blackwell Publishing Ltd    

年代:1943

数据来源: WILEY

摘要:

AbstractThe effects of time and temperature on the chemical attack of glasses by water are represented by the equation; α logN= logθ ‐ b/T+c;N= attack; θ= time;T =absolute temperature, °K;a, b, andc, are experimentally determined constants. The constant,b, of the equation is independent of the glass composition and of the size and shape of the sample tested and has a value of 5080 for tests of ordinary glass containers. As a time‐temperature function, the equation may be written as log θ=b/T ‐ C, in which form it is useful for estimating the storage or service conditions equivalent to art accelerated test or for calculating the conditions of alternate tests. Data from the literature are used in demonstrating the accuracy and usefulness of th

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1943.tb15211.x

出版商:Blackwell Publishing Ltd    

年代:1943

数据来源: WILEY