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doi: 10.1111/j.1151-2916.1955.tb14921.xpmid: N/A
These ternary systems are limiting faces, respectively, of the volumes leucite‐corundum‐spinel‐silica and leucite‐forsterite‐spinel‐silica in the quaternary system K2O–MgO–Al2O3–SiO2. The results of quenching experiments on these two ternary systems and on the binary system spinel‐leucite are given here. The relation of the system leucite‐corundum‐spinel to the volume leucite‐corundum‐spinel‐K2O·Al2O3·2SiO2 is indicated. The data presented are of general interest to the geologist and provide basic information which can be applied to refractories and slags by the ceramist and metallurgist. Some observations are made on the refractoriness and changes in refractoriness of certain mixtures of ceramic materials.
DeVRIES, R. C.; ROY, R.; OSBORN, E. F.
doi: 10.1111/j.1151-2916.1955.tb14922.xpmid: N/A
Results of a study of phase equilibria in the system CaO–TiO2–SiO2 are presented. A prominent feature of the liquidus surface is a large two‐liquid region which appears on the equilibrium diagram as a broad band extending from the SiO2‐CaO side to the SiO2‐TiO2 side of the triangle. Evidence for the liquid immiscibility and the significance of the resulting large high‐temperature liquidus region in silicate technology are discussed. Representative paths of crystallization of liquids in the system under equilibrium conditions are outlined. It is shown that solid solution in the system is virtually nonexistent except for the small‐scale substitution of Ti4+ for Si4+ in wollastonite. Indices of refraction of glasses are given. Composition and temperature are listed for the twelve liquidus ternary invariant points.
doi: 10.1111/j.1151-2916.1955.tb14923.xpmid: N/A
A theory of the structure of glasses is presented. It is assumed that the volume and various other properties can be computed additively from contributions characteristic of the types of “structon” present, a structon being defined as an atom surrounded by close neighbors in a specific way. If the possible types of structon differ enough in stability, the number of such types present in appreciable quantities in a sample at equilibrium is small. If it is the minimum number required to give the correct over‐all composition, the sets of structon types present change suddenly as the composition changes. This explains the observed fact that certain property‐composition curves consist of straight‐line segments, with sharp breaks between them. Detailed consideration is given to the volumes (and densities) of well‐annealed sodium silicate glasses. Reasonable sets of structon types account quantitatively for the locations of the observed breaks. Certain definite conclusions are drawn regarding the types of structon present in the different composition ranges, their relative numbers, and their contributions to the total volume.
doi: 10.1111/j.1151-2916.1955.tb14924.xpmid: N/A
The chemical resistance of mixed‐alkali glasses to water was measured by determining the sodium, potassium, calcium, and silicon ions extracted instead of evaluating it from the alkalinity of the mixed‐alkali extracts. In glasses of the composition K2O and Na2O 18, CaO 10, and SiO2 72% the minimum extraction of alkali (maximum durability) occurred for a K2O/‐Na2O ratio of 2.6/1.0 (by weight). Based on an ionic‐composition analysis of the results, an empirical index is suggested for determining the relative degree of ion‐exchange and network‐breakdown modes of reactions that occur when such mixed‐alkali glasses are attacked by water.
doi: 10.1111/j.1151-2916.1955.tb14925.xpmid: N/A
A method was devised whereby moisture‐condensation patterns on glass and crystalline surfaces could be examined under the microscope and photographed. The characteristics of the condensation films were markedly influenced by the fracture patterns and by the structure of the underlying surface. The technique was applied in a detailed study of minute surface fracture patterns and Griffith flaws. Experiments were made showing the type of fracture patterns produced on glass by various mechanical means. Variations in the surface structure produced by polishing, etching, and other treatments were also studied by this method.
doi: 10.1111/j.1151-2916.1955.tb14926.xpmid: N/A
A method is described by which the viscosity of glass can be estimated in the range 100 to 450 poises by determining the relationship between temperature and the quantity of glass in fiber form which can be drawn from an orifice in unit time. Results are based on a comparison with an arbitrarily chosen standard glass. The method is relatively rapid, yields good precision, and can be used to make samples of fibers valuable for other tests.
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