bluuebunny/crossref_metadata_2025 huggingface dataset:
Activities in Borosilicate Melts: II, Some Mixtures of Calcium Borates‐Calcium Silicates
Authors: KNAPP W. J. , FLOOD H.
Published: June 2006

Simple expressions of activities, as functions of composition, were developed from structural models for some borosilicate melts. Their applicability was tested with data from the liquidus curves of phase diagrams. If the heat of fusion is known, a value of the activity‐composition function can be calculated for each temperature of the liquidus curve. These values are compared with activities computed from the structural model. Calorimetric heats of fusion were available for the calcium borates studied. Experimental data from published phase diagrams for the systems Ca3(BO3)2–Ca2SiO4, Ca2B2O6–Ca2SiO4, Ca3(BO3)2–CaSiO3, Ca(BO2)–CaSiO3, Ca2B2O5–CaSiO3, CaSiO3–BaSiO3, and CaSiO3–K2SiO3 were used. Simple ionic models seemed to be applicable in most cases, except for melts of highly polymerized mixed ions (metaborate‐metasilicate), for which the so‐called “group” model appeared to be useful. A value for the heat of fusion of CaSiO3 was calculated from this work (13,200 cal. per mole).
Mechanical Strength of Porcelain
Authors: MATTYASOVSZKY‐ZSOLNAY LÁSZLÓ
Published: June 2006

The mechanical strength of porcelain, in which a glassy phase is the major part, is shown to be influenced mainly by stresses set up in the glassy phase rather than by the amount or size of mullite crystals formed. A crystalbe material (quartz) having a coefficient of expansion higher than that of the glassy phase will establish favorable prestresses in the glassy phase. As the tensile stresses induced in the quartz are relatively high, uniformly sized grains of about 15 to 30 μ will best withstand these stresses. If finer‐sized quartz grains are used, they will dissolve on firing and will not contribute to favorable prestressing of the matrix. The maximum prestresses are obtained when the radius of the quartz grains is three times that of the surface layer dissolved on firing. Illite, as a flux, tends to dissolve only a thin layer up to the maturing of the porcelain, but increases its action at the maturing temperature, thereby increasing the favorable prestressing. Another factor is the temperature gradient inside the body during firing, which causes gradual differences in the coefficients of expansion because of quartz dissolution. As the coefficient of expansion is lower near the surface than near the center, additional favorable prestresses are established.
Phase Relationships in the System Zirconia—Thoria
Authors: DUWEZ POL , LOH EUGENE
Published: June 2006

The phase relationships in the system zirconia‐thoria were investigated by X‐ray diffraction and dilatometric methods. The specimens were melted in air at the focus of a solar furnace. The existence of a cubic calcium fluoride‐type solid solution was established for thoria concentrations above 17.5 mole %. However, this solid solution is stable only at high temperature, and, after prolonged heating at 2000°C. and at 1350°C., it decomposes into tetragonal zirconia (which during subsequent cooling undergoes the unavoidable tetragonal‐monoclinic inversion) and a thoria‐rich phase containing at least 99 mole % thoria.
Effect of Water on Mechanical Strength of Selected Ceramic Compositions
Authors: SMOTHERS W. J.
Published: June 2006

The strength of unglazed feldspathic porcelain test bars in air decreased with humidity at the time of breaking. Moderate vacuum increased strength. N2, CO2, O2, and H2 were not effective in changing porcelain strength with respect to that in ambient air. Use of a so‐called compression glaze eliminated the deleterious effect of water. Several organic liquids, as coatings on unglazed test bars, were evaluated. Tests with acid and basic solutions indicated that porcelain strength decreased with an increase in the mole % of water present in the liquid coating.
Determination of Several Valences of Iron, Arsenic and Antimony, and Selenium in Glass
Authors: CLOSE PAUL , SHEPHERD H. M. , DRUMMOND C. H.
Published: June 2006

Methods for the analysis of silicate glasses are described for ferrous iron, for tri‐ and pentavalent arsenic and antimony when present together, and for selenium as Se2‐, Se°, Se4+, and Se6+. Analytical results are presented for FeO in the range 0 to 0.25%; for total As and Sb as tri‐oxide, 0.1 to 1.25%; and for total Se, 0.05 to 0.25%. Apparatus for the determination of FeO is described, and a comparison is made of analytical data for FeO versus light transmittance at 1000 and at 1050 mμ for the same glass.
Note on Calculation of Effect of Temperature and Composition on Specific Heat of Glass
Authors: MOORE JOHN , SHARP D. E.
Published: June 2006

The specific heats of glasses reported in the literature since 1951 were studied in relation to the Sharp‐Ginther equation. It was found necessary to change the factors previously furnished for K2O and B2O3. The other factors were found to be satisfactory when compared with the new measurements. It was discovered that glasses containing oxides of metals with atomic weights above 50 (e.g. iron, lead, and zinc) did not accurately fit the Sharp‐Ginther equation over the complete temperature range desired. Provisional factors were calculated, however, for iron and manganese oxides from 0° to 600° C.
Ferrites
Authors: ALBERS‐SCHOENBERG ERNST
Published: June 2006

Ferrites are magnetic iron oxide compounds having, in general, the spinel structure. Because of their high resistivity as compared to magnetic alloys, they are used wherever high frequencies are involved. During the last 15 years several distinct classes of ferrites have been developed, different with respect to chemical constitution as well as application. These include Ni‐Zn and Mn‐Zn ferrites for transformer cores, cup cores, and radio antennas, barium ferrites for permanent magnets, Mg‐Mn ferrites for signal storage, and high insulating ferrites for microwave equipment. Specialized production equipment has helped greatly in the commercial realization of well‐defined properties.
Microstructure and Properties of Ferrites
Authors: BLUM S. L.
Published: June 2006

Microstructure significantly affects the magnetic and electrical properties of ferrites. Domain behavior and its relation to microstructure of magnetic materials are reviewed, and the critical grain size necessary to maintain a single domain in nickel ferrite is calculated. Experimental data are given for BaO. 6Fe2 O3 and NiFe2O4 to show the relations among grain sue, coercive force, permeability, ferromagnetic resonance line width (ΔH), and dielectric losses. Predictions are made for the role of ferrites in the future of ceramic research.
A Review of Developments and Current Trends in Ceramic Dielectrics Used for Capacitor Applications
Authors: ROUP ROLLAND R.
Published: June 2006

A review is made of currently produced titanate ceramic dielectric materials designed for close‐tolerance temperature‐compensating and for general purpose capacitors. Data are presented on capacitors made from semiconducting titanate dielectrics in which the capacitance values range from 50 to 400 times higher than values obtainable in similar sized units of conventional dielectric material having a dielectric constant of 6000.
Ceramic Electrical Insulating Materials
Authors: RIGTERINK M. D.
Published: June 2006

During the past 30 years, the principal ceramic insulating materials have been the electrical porcelains, the steatites, and the high alumina bodies. The compositions, the structures, and the properties of these materials are discussed. Other porcelains and insulating compositions, containing as their principal crystalline phases mullite, zircon, forsterite, cordierite, wollastonite, or β‐spodumene, have unusual properties and are useful for specialty items. Predictions of future trends in ceramic insulating materials are made.
Influence of Reaction Products on Reaction Between Water and Soda‐Lime‐Silica Glass
Authors: WANG FRANKLIN FU‐YEN , TOOLEY F. V.
Published: June 2006

The collective effects of the reaction products on the reaction between water and soda‐lime‐silica glass were studied by investigating the reactions of the glass with each individual reaction product. The rate‐controlling processes in the reaction between water and the glass are considered to be the diffusion of cations and the breakdown of the glass network. A qualitative description of the mechanism of the reaction between the glass and water is suggested.
Investigation of Silicate Groups in Fused Mixtures by Phase Diagram Measurements
Authors: FORLAND TORMOD
Published: June 2006

The sulfate side of the phase diagram of the system NazSO4‐Na2SiO3 has been investigated by means of a high‐temperature filtration technique. On the basis of the measurements obtained it is concluded that the metasilicate forms rings of four tetrahedra when dissolved in sodium sulfate. The results for this system are compared with data from other related silicate‐containing mixtures.
Effect of Composition of Kiln Atmosphere in the Firing of Refractory Oxides
Authors: SANDFORD FOLKE , ERICSSON ERLAND
Published: June 2006

The experimental results given in this paper show that (1) alumina lost oxygen when heated at 1400° to 1500°C. in water vapor but retained its weight unchanged when heated in air or in nitrogen and (2) kiln gases dissolved in a mullitic material at temperatures between 800° and 1200°C., and their solubility increased with temperature. These separate facts verify two theories that often have been suggested to explain the effect of the composition of the kiln atmosphere, viz., that (a) deviation from the stoichiometric composition occurs in stable ceramic oxides, such as Al2O3, at moderately elevated temperatures, even though the ambient gas phase does not affect the ceramic oxide in the ordinary chemical sense, and (b) lattice defects are caused by the solution of gases in the ceramic oxides. The frequency of lattice defects is assumed to depend on the surrounding gas phase.
Effect of Oxygen Pressure on Microstructure and Coercive Force of Magnesium Ferrite
Authors: CARTER R. E.
Published: June 2006

The precipitate formed during partial reduction of magnesium ferrite raises the coercive force by setting up high stresses in the ferrite matrix as a result of the difference in thermal expansion of the two phases. The slower the cooling rate, the smaller is the final stress and the smaller the influence on the coercive force. Only the magnitude and not the sign of the difference in thermal expansion is of importance, as is shown by making additions of inert phases with thermal expansions both larger and smaller than that of the ferrite. The maximum radial tensile stress set up in the ferrite by the reduced phase is approximately 40,000 1b. per sq. in. in a specimen air‐quenched from 1400° C. The formation of a reduced phase in magnesium ferrite is accompanied by a fourfold reduction of the residual porosity. It is not known whether this is the result of a change in stoichiometry of the ferrite with the development of an oxygen‐deficient structure and hence enhanced oxygen diffusion rate, or whether the reduced phase prevents grain growth until most of the vacancies have collapsed. The reoxidation of such a two‐phase material gives a polycrystalline material with greatly improved magnetic properties.
On the Adherence of Porcelain Enamel to Sheet Steel
Authors: BERK JAN , de JONG JAN
Published: June 2006

A study of the reactions at the interface of enamels and steel during firing has been made using a reflecting microscope, an electron microscope, an X‐ray spectrometer, and a light spectrograph. Much attention has been given to the tendency of a number of oxides, e.g., cobalt oxide and nickel oxide, to develop a typical roughening of the base metal during firing. This roughening appears to be caused by two successive electrochemical reactions at the interface of the enamel and steel. With the aid of the results, a short explanation is given of the various ways in which enamels may adhere to steel.
Studies in the System CaO‐Al2O3‐SiO2H2O: III, New Data on the Polymorphism of Ca2SiO2 and Its Stability in the System CaO‐SiO2‐ H2O
Authors: ROY DELLA M.
Published: June 2006

The nature of the low‐temperature inversions γ‐α' and α'‐β was investigated by various techniques: hydrothermal and “dry” quenching runs, differential thermal analysis at atmospheric and elevated nitrogen pressures, X‐ray diffractometer patterns obtained at elevated temperatures, “static” pressure techniques, and infrared absorption spectrometry. A revised energy‐temperature diagram is presented for Ca2SiO4, with the transition γ' to α' taking place at about 725°C. and the α'‐β transition, although not reversible at an exact temperature, taking place at about 670° C. At low water pressures (2000 lb. per sq. in.) the inversion γ‐α' was placed at 675°C. Attempts to extrapolate the value obtained at 2000 lb. per sq. in. to obtain a more accurate reversible inversion temperature at atmospheric pressure, although limited in accuracy by the reliability of heat‐of‐transition data, would indicate a temperature of about 725° C. at atmospheric pressure. Three new compounds, 8CaO.3SiO2 ‐3H2O (X), 6CaO 3SiO2.H2O (Y), and 9CaO‐6SiO2 H2O (Z), were found to be stable above 700°C. at H2O pressures greater than 7500 lb. per sq. in.
Optical and Physical Properties of Some Calcium Aluminate Glasses
Authors: HAFNER H. C. , KREIDL N. J. , WEIDEL R. A.
Published: June 2006

Calcium aluminate glasses containing alkali oxides and iron oxide will transmit infrared radiation to about 6 μ and still have satisfactory working properties. Their refractive index, density, expansion, Young's modulus, modulus of rupture, fracture velocity, Knoop hardness, and some electrical and chemical properties are evaluated.
Viscosity, Density, and Electrical Resistivity of Molten Alkaline‐Earth Borate Glasses with 3 Mole % of Potassium Oxide
Authors: COUGHANOUR L.W. , SHARTSIS LEO , SHERMER H. F.
Published: June 2006

Viscosity, density, and electrical resistivity were determined on three series of molten alkaline‐earth borate glasses, each containing 3 mole % of potassium oxide. A previous investigation of these properties of the binary alkaline‐earth borates was limited by the formation of two immiscible liquids at low alkaline‐earth oxide concentrations. To overcome this difficulty 3 mole % of K2O was added to each composition. The properties of this new series of glasses were compared with the previous work. The densities at room and elevated temperatures were in the order BaO > SrO > CaO on a mole per cent basis. The reverse order was noted for the viscosity data. The electrical resistivity decreased with increasing concentration of alkaline‐earth oxide at 1000°C. and at 1100°C. but increased at 800°C. and at 900°C.
Some Observations on the Wetting of Al2O3, by Aluminum
Authors: CARNAHAN R. D. , JOHNSTONr T. L. , LI C. H.
Published: June 2006

The contact angle of liquid aluminum with recrystallized alumina and with sapphire, respectively, was measured using the sessile‐drop technique, The variation in contact angle with time was determined at temperatures of the order of 1200°C. in vacuo at 10‐4 mm. Hg. A significant difference in spreading behavior was observed for aluminum on the respective aluminas. In the case of aluminum on recrystallized Al2O3 the contact angle attained a steady value, whereas on sapphire the drop was observed to spread and contract repeatedly. The contact angle assumed after each contraction was essentially constant. The observations are discussed and an explanation is proposed for the effect in terms of changes in the interfacial geometry between liquid aluminum and the alumina due to dissolution.
Infrared‐Transmitting Glasses in the System K2O‐Sb2O3‐Sb2S3
Authors: KING BURNHAM W. , KELLY GEORGE D.
Published: June 2006

Glasses were discovered in the system K2O‐Sb2O3b3 Raw materials used in the preparation of these glasses were potassium pyroantimonate, potassium hydroxide, potassium nitrate, antimony oxide, and antimony trisulfide. Details of the methods of preparing the glasses and the compositions investigated are given. A glass, prepared by melting a mixture of potassium pyroantimonate and antimony trisulfide in air, was investigated in some detail. It was found to have an average infrared transmission of 42% in the range 2 to 7 μ. The glass annealed at about 150°C. and softened at about 230°C. Its coefficient of linear thermal expansion, in the range 240° to 200°C., was 20 × 10−6 per °C. The glass had a specific gravity of 3.94, a modulus of elasticity of about 5 × 106lb. per sq. in., a Knoop hardness of about 135, and was highly resistant to attack by atmospheric moisture.
Tension Stresses in Glass Coatings and in Glass‐Metal Seals in the Annealing Range
Authors: TURNBULL J. C.
Published: June 2006

The strength of glass coatings applied to metals was found to decrease with time at temperatures in the lower annealing range. This decrease is caused by the well‐known decrease in volume which glasses undergo at these temperatures. Glasses applied to a metal surface are constrained in directions parallel to the surface, and the decrease in volume thus produces tension strains in these directions. In this temperature range, the production of tension stress due to density increase is partly offset by stress release due to viscous flow. These effects, calculated from measurements of density variation and of stress release in the glass used for coating, were found to indicate variations in glass strength which agreed approximately with values measured by a cross‐bending test. Significant tension stresses of similar origin were observed to appear in glass‐metal seals during baking in the lower annealing range.
Relationship Between Hydrogen Solubility and Reboiling Tendency in Enameling Steels
Authors: HUDSON R. M. , MAGOR J. K. , STRAGAND G. L.
Published: June 2006

Enameling steels that had exhibited various degrees of reboiling behavior after ground‐coat enameling were charged with hydrogen to saturation by immersion in 2 N sulfuric acid at 38° C. Hydrogen contents were then determined by warm extraction at 160° C. under mercury. It is shown that for a given grade of steel the specimens which had been rated as heavy reboilers in the enameling tests occluded at 38° C. considerably less hydrogen than those rated as trace or light reboilers. A given level of hydrogen solubility, however, does not necessarily indicate the same reboiling tendency for different grades of steel. The determination of hydrogen solubility by the techniques described provides a method of indicating the reboiling tendency of a particular steel that is independent of the effects introduced by ground‐coat composition.
Elasticity, Strength, and Other Related Properties of Some Refractory Castables
Authors: SCHNEIDER S. J. , MONG L. E.
Published: June 2006

Young's modulus of elasticity, transverse strength, extensibility, and load resistance were determined at a series of test temperatures on six groups of laboratory‐prepared refractory castables which had (a) no heat‐treatment, (b) heat‐treatment at 1050°C., and (c) heat‐treatment at 1300°C. The data suggested that the alterations in composition that occur with a rise in temperature were related to corresponding changes in modulus of elasticity and strength. The effects of dehydration, conversion of amorphous alumina to γ‐alumina, and silica inversions were evident. The cement content and temperature of operation as well as the heat‐treatment of the castables affected all these mechanical properties to varying degrees.
Effect of Heat‐Treatment on Properties of Enamel‐Steel Composites
Authors: HEALY J. H. , BREEZE L. K.
Published: June 2006

The tangential deflection was measured on glass‐steel strips that were heat‐treated below, as well as in, the transition zone of the glass. The change in tangential deflection after heat‐treatment was similar to the change in flexure breaking stress, thermal‐shock resistance, resistance to' fish scaling, and spalling of glass in an acid environment after heat‐treatment.
Effect of Oxide Additions on Sintering of Magnesia
Authors: NELSON JAMES W. , CUTLER IVAN B.
Published: June 2006

The effect of transition metal, alkali, alkaline‐earth, and heavy metal oxide additions on the sintering of magnesia was determined by measuring bulk density and shrinkage. Polished specimens were made on selected compositions and the grain structure was photographed. The unusual effect of titanium, zirconium, silicon, lithium, iron, and zinc oxides in promoting high sintered densities is explained on the basis of the defective crystal structure produced by these additions.
Differential Thermal Analysis Above 1200°C.
Authors: NEWKIRK TERRY F.
Published: June 2006

Differential thermal analysis techniques and equipment for use at temperatures up to 1550°C. are described. Proper electrical shielding eliminates the spurious effects ordinarily encountered above about 1200°C. For nonvolatile materials a pellet method requiring no container and only 0.1 to 0.2 gm. of sample has been developed. For systems containing volatile components, covered crucibles are used. Examples are given of typical DTA curves obtained from pellets of CaO‐Al2O3‐Fe2O3 mixtures. The interpretation of DTA heating curves to give precise solidus and liquidus data is discussed briefly.
Color and Light Scattering of Platinum in Some Lead Glasses
Authors: RYDER R. J. , RINDONE G. E.
Published: June 2006

The coloration and light scattering of sodium lead silicate, borate, and phosphate glasses containing platinum, introduced as PtCl4, have been studied. Under the normal atmosphere of a furnace heated by silicon carbide elements, the platinum is retained in the colloidal state in the sodium lead silicates and borates, producing gray glasses. In the phosphate glasses yellow to orange ionic colors as well as grays are produced. Lead oxide increases the stability of platinum ions in the phosphate glasses. Under strong oxidizing conditions, ionic platinum also can be obtained in the borate and silicate glasses. Tyndall scattering can be detected in what appear to be clear, colorless glasses. This light scattering has been observed in some glasses containing as little as 1 p.p.m. platinum.
Lightweight Structural Clay Products Made with Vermiculite
Authors: ROBINSON GILBERT C.
Published: June 2006

Tests were made to determine desirable manufacturing procedures for structural clay units made from mixtures of clay and vermiculite. It was found that the use of correct manufacturing procedures would produce a structural unit with a bulk density approximately one‐half that of conventional structural clay products. Such a unit had a crushing strength in excess of 1500 lb. per sq. in. The unit could be easily sawed and machined and could be finished with glazes or engobes.
Crystal Chemistry of Hydrous Calcium Silicates: III, Morphology and Other Properties of Tobermorite and Related Phases
Authors: KALOUSEK G. L. , PREBUS ALBERT F.
Published: June 2006

Three very similar hydrous calcium silicates that serve as binders for, or are closely related to the binding material of, autoclaved and moist‐air‐cured concrete and related products have been differentiated by electron microscopy, X‐ray diffraction, differential thermal analysis, infrared absorption, degree of stability to the acetoacetic ester, and oxide composition. Tobermorite, 4–5CaO.5SiO2.5H2O, is the binder of properly autoclaved concrete and related products. It integrates uniformly into a dimension‐ally stable solid of high strength. This phase is identified by X‐ray diffraction lines at 11, 3.07, and 2.97 a.u. of strong intensity, by a basal spacing at 11 a.u., and by a flat platy crystal habit. The analogous hydrate of similar CaO/SiO2 molar ratio (C/S) and designated the 0.8 to 1.33 C/S hydrate, generally shows a basal spacing at 14 a.u., occurs in crinkly foils, and exhibits a strong exothermic effect in differential thermal analysis at 835° C. This phase differs markedly from tobermorite, does not undergo any crystal‐to‐crystal binding, and shows some of the physical characteristics of clay. It is the low‐lime intermediate in the formation of tobermorite. The binder of low‐pressure‐steam‐cured concrete occurs in part in gel‐like globules, sometimes in the shape of spheres. This phase, having a probable composition anywhere between 1.5 and 2.0 C/S, depending on the time of curing, is characterized by the gel‐like morphological characteristic, a basal spacing of about 10 a.u., and variable but still characteristic differential thermal analysis effects. Apparently the same product is obtained by reacting lime and silicic acid, but it Occurs in the form of distinctly fibrous crystals.
Factors Involved in Plasticity of Kaolin‐Water Systems
Authors: LAWRENCE W. G.
Published: June 2006

The factors involved in the development of plasticity are discussed. The importance of the rigidity of the adsorbed water ms and the effect of various ions on this rigidity is shown by entropy calculations. All the monovalent ions with the exception of the smallest (Li+ and F−) indicate an increase in the disorder of the water structure that agrees with observations on plasticity.
Solidus, Subsolidus, and Subdissociation Phase Equilibria in the System Fe‐Al‐O
Authors: ATLAS L. M. , SUMIDA W. K.
Published: June 2006

The objective of this investigation was to determine phase relations in the system Fe‐Al‐O outside the composition and temperature regions of oxygen dissociation. Subsolidus phase equilibria were studied using inert atmospheres and the quenching technique. Compatibility relations are presented on isothermal sections at 1000°, 1250°, and 1350°C. Lattice parameters of iron‐bearing spinel, Al2O3and Fe2O3 are given as a function of composition. Stability and some structural relations of the compound Fe2O3 Al2O3 are discussed. Solidus surfaces in the nondissociating portions of the system have been established using both published data and measurements made during this investigation.
Etching of Refractories and Cermets by Ion Bombardment
Authors: BIERLEIN T. K. , NEWKIRK H. W. , MASTEL B.
Published: June 2006

Uranium oxide, aluminum oxide, and porcelain, as well as aluminum‐aluminum oxide (SAP), a nickel‐titanium carbide base cermet (Kentanium K‐152‐B), and a cobalt silicide‐titanium carbide, titanium diboride cermet (designated III‐B), typical examples of refractories and cermets, have been satisfactorily etched by ion bombardment for subsequent optical and electron microscope study. The method used is similar in almost all respects to the ion etching of metallic specimens. Representative optical and electron micrographs illustrate the applicability of the method for developing the microstructure of refractories and cermets.
Sintering and Hot Pressing of Uranium Tetrafluoride
Authors: BARNES E. , MURRAY P.
Published: June 2006

The basic sintering and hot‐pressing conditions have been established for UF4. Either sintering of cold compacted material in argon or direct hot pressing in graphite dies can be used satisfactorily to obtain high‐bulk‐density compacts. Vacuum sintering is ruled out because of the volatility of the UF4. The occurrence of black localized areas in both sintered and hot‐pressed material is attributed to the internal distortion of fluorine atoms into lattice voids resulting in the formation of strained areas.
Factors Influencing the Neutral Point of Porcelain Enamels
Authors: BOWMAN D. C.
Published: June 2006

The temperature at which a porcelain enamel‐metal system reaches stress equilibrium is designated as the neutral point. The effect on this neutral point of such variables as frit fusibility mill formulation, processing, and thermal history has been investigated.
Control of Factors Affecting Reproducibility of Mechanical Properties of Refractory Semidry Press Specimens
Authors: MONG L. E. , ADELMAN D. M.
Published: June 2006

The factors that affect the uniformity of semidry press refractories were studied. Specimens were made from batches having either raw flint clay or calcined flint clay as the granular material. They were formed by uniaxial pressing in a steel mold or by hydrostatic pressing in a rubber mold. Refinements in the control of factors that affect reproducibility, including particle sizing, mixing, forming, drying, and heat‐treating, are discussed. Modulus of elasticity and strength in tension were obtained, and the average values, coefficients of variation, and strain variability within the specimen were the criteria of reproducibility. All specimens of this particular material developed pressure cracks after forming in a steel mold. Sound specimens having reasonable reproducibility were obtained by hydrostatic molding and strict control of other variables. Specimens made from calcined grog were the most reproducible.
Oxidation of Iron Pretreated for Porcelain Enameling
Authors: FUSSELL L. E. , HADLEY R. L.
Published: June 2006

The thickness of oxide layers formed on enameling iron at short times was measured as a function of temperature to compare the effects of three pretreatments: (1) sulfuric acid pickle, (2) nickel flash, and (3) phosphate coating. The oxides present were examined by X‐ray diffraction and metallographic techniques. Nickel‐flashed specimens exhibited lowered oxidation rates. The phosphate coating produced significantly rougher metal‐oxide interfaces under the process conditions used.
Studies in Lithium Oxide Systems: II, Li2O Al2O3–Al2 O 3
Authors: HUMMEL F. A. , SASTRY B. S. R. , WOTRING DEAN
Published: June 2006

Solid‐state reactions between Li2O and Al2 O3 were studied in the region between Li2O.Al2 O 3 and Al2 O 3. The compound Li2 O Al2 O 3 melts at 1610°± 15°C. and undergoes a rapid reversible inversion between 1200° and 1300°C. Vaporization of Li2 O from compositions in the system proceeds at an appreciable rate at 1400°C, as shown by fluorescence. Lithium spinel, Li2 O ‐5Al2O3, was the only other compound observed. The effect of Li2 O on the sintering of alumina was investigated.
Determination of Residual Stresses in Titanium Carbide‐Base Cermets by High‐Temperature X‐Ray Diffraction
Authors: NEWKIRK HERBERT W. , SISLER HARRY H.
Published: June 2006

The crystal structure and thermal expansion of titanium carbide, nickel, and two titanium carbide‐base cermets were determined between room temperature and 1100°C. (2012°F.). No structural changes were observed. An abnormal rate of expansion was observed for pure nickel near the Curie temperature, 353°C. (665°F.), and for the nickel and carbide phases in the cermets at about 816°C. (1500°F.). The expansion coefficient of pure nickel and the nickel phase in the cermets was found to be approximately twice that of pure titanium carbide and the carbide phase in the cermets. The brittleness and poor impact strength of the cermets was attributed to the large residual stresses present in these materials as a result of this difference in thermal expansion. The stress‐strain relations were interpreted on the basis of a mechanical interaction between the phases in the cermets. The carbide phase was found to be essentially under triaxial compression and the nickel phase under a triaxial tension of 158,000 lb. per sq. in. At elevated temperatures, increased solid solubility of carbide in the nickel phase and plastic deformation of this phase was believed to influence the stress‐strain relations and the thermal‐expansion behavior of the phases. It was concluded that replacement of the nickel phase in the cermets with a metal or alloy, such as a nickel‐chromium‐molybdenum alloy, which has a coefficient of thermal expansion similar to the carbide phase in the cermets, would improve the impact strength of these bodies. Equations were developed for the thermal expansion of titanium carbide and nickel. Values of the expansion coefficient were computed for each of the materials by differentiation of these equations.
Stress Measurement in Circular Cylinders
Authors: SUTTON PAUL M.
Published: June 2006

A general procedure is presented whereby all the internal stresses in a glass cylinder can be calculated from birefringence observations. The method applies to circular cylinders, either rods or tubes, where the stress distribution may be any arbitrary function of the radial coordinate and where the observation path is far enough from the ends of the cylinder so that end effects are negligible. The method is applied to an oil‐tempered solid glass rod and the calculated stress is compared with that expected from a constant cooling rate.
Factorial Design of Experiments in Ceramics, l
Authors: SMITH DON , JONES P. R.
Published: June 2006

A factorial design of experiment is one in which a variable is evaluated at all levels of all other variables. This type of experiment was applied to the unit operations in body preparation and forming by extrusion. Drying and firing unit operations were not considered, and the variance due to these operations was minimized by duplication. The variables or factors were (1) particle‐size distribution at three levels, (2) water of plasticity at two levels, (3) entrapped air at two levels, and (4) two replications. Analysis of variance was used to determine the significant effects. It was found that 95%. 0f the total variance of the drying shrinkage was accounted for by the particle‐size distribution, water of plasticity, and two interactions; 95% of the total variance of the dry modulus of rupture was accounted for by particle‐size distribution, water of plasticity, entrapped air, and two interactions; 52% of the total variance of the firing shrinkage was accounted for by the particle‐size distribution; 87% of the total variance of the fired modulus of rupture was accounted for by the particle‐size distribution, water of plasticity, entrapped air, and three interactions. Since a tunnel kiln makes it possible to control the firing operation closely and with no changes in composition, close control of the particle‐size distribution, water of plasticity, and entrapped air should make it possible to produce more uniform ware. The slope constants for the factors were also determined which show the most efficient path leading to the development of optimum conditions necessary for maximizing a desired property.
Surface Tension of Some Liquid Oxides and Their Temperature Coefficients
Authors: KINGERY W. D.
Published: June 2006

Surface‐tension data are reported for liquid Al2 O3, B2 O3, GeO2, P2 O5, and SiO2. Abnormal positive temperature coefficients for B2 O3, GeO2, and SiO2 are shown to be due mainly to changes in the liquid structure (dissociation) with temperature.
Tricalcium Silicate and Its Stability Within the System CaO‐SiO2
Authors: WELCH J. H. , GUTT W.
Published: June 2006

A portion of the system CaO‐SiO2 has been reinvestigated by high‐temperature microscopy. Direct observations at the liquidus establish a primary‐phase region for tricalcium silicate, which is shown in a revised phase diagram to melt incongruently. The tricalcium silicate primary‐phase field extends from the eutectic with dicalcium silicate at 2050 °C., 69.5% CaO, to the incongruent boundary with lime at 2070°C., 71.5% CaO, with a possible error in composition of ± 0.25%. The estimated accuracy of these temperatures is ±3° relative to one another, and ± 10° relative to the melting points of alumina and dicalcium silicate, for which the values 2040°C. and 2130°C. taken from the literature have been assumed.
Equilibrium and Pseudo Equilibrium Low‐Temperature Dehydration of Montmorillonoids
Authors: CROWLEY M. S. , ROY RUSTUM
Published: June 2006

Data have been obtained on the corresponding partial water pressures and temperatures at which hydrated montmorillonites will dehydrate reversibly. The data support but cannot establish (unequivocally) the idea that mixed‐layer phases are metastable with respect to gross mixtures and usually persist metastably in the stability field of either the dehydrated or the hydrated phase. The influence of the host lattice (montmorillonite. or saponite, and the interlayer cation, Mg2+, Ca2+, Na+, and Pb2+) is clearly shown in the pressure‐temperature curves presented.
Phase Equilibria in the Alkali Fluoride‐Uranium Tetrafluoride Fused Salt Systems: III, The System NaF–LiF–UF4
Authors: THOMA R. E. , INSLEY HERBERT , LANDAU B. S. , FRIEDMAN H. A. , GRIMES W. R.
Published: June 2006

The phase equilibrium diagram of the ternary system NaF–LiF–UF4 described in this paper is based on evidence from thermal analysis and from microscopic and X‐ray analyses of samples obtained from thermal gradient quenching experiments. Temperature‐composition relations were established through the temperature interval between the liquidus and a lower limit of about 300°C. All the stable compounds in the binary systems LiF–UF4 and NaF‐UF4, (including the subsolidus compound NaF·2UF4) display primary phase fields in the ternary system. No ternary compounds of NaF–LiF–UF4 occur. The following eutectics are to be found in the ternary system: 60 NaF, 21 LiF, 19 mole % UF4, 480°C.; 35 NaF, 37 LiF, 28 mole % UF4, 480°C.; 24.3 NaF, 43.5 LiF, 32.2 mole % UF4, 445°C.; and 24.5 NaF, 29 LiF, 46.5 mole % UF4, 602°C. The compounds 7NaF · 6UF4 and 7LiF · 6UF4 display limited solubility in each other. The exact limits of the miscibility gap in the 7NaF · 6UF4‐7LiF · 6UF4 join have not been determined.
Cermets From Thermite Reactions
Authors: WALTON J. D. , POULOS N. E.
Published: June 2006

The process whereby the components of a thermite are pressed into a desired shape and ignited to form a cermet is described. In this process, the oxide of the cermet (Al2O3) is produced from the oxidation of powdered aluminum and the metallic phase is produced from the resulting reduction of its oxide. A third component (clay, Al2O3, or MgO) is added to act as a control agent. Methods of compacting and firing are described. A table of oxides reduced by aluminum using this process is presented. The formation of metallic silicides and borides as the metallic phase of a cermet from the appropriate silicates and borates, or metallic oxides with silica or boric acid, is discussed. As an example, ZrSi2 is produced by the reduction of either ZrSiO4 or ZrO2 and SiO2, and TiB2 by the reduction of TiO2 and B2O3. The following advantages may be obtained by this method: (1) inexpensive compositions, (2) low ignition temperatures (1800°F.), (3) high reaction temperatures (5000°F.), (4) short firing time (1 hour), and (5) controlled atmosphere unnecessary. A technique was developed whereby cermet test specimens could be prepared from the thermite reaction between aluminum and zirconium silicate. The tensile strength of the finished cermet is given at room temperature and at 2200°F. The apparatus used for determining these tensile strengths is described. Modulus of rupture data also are given. Other oxide thermites were added to the basic zirconium silicate thermite mixture. The effect of these thermite additions on the strength of the basic thermite is described.
Electromechanical Properties of Lead Titanate Zirconate Ceramics with Lead Partially Replaced by Calcium or Strontium
Authors: KULCSAR FRANK
Published: June 2006

By partially substituting Sr for Pb in ceramic lead titanate zirconate compositions near the morpho‐tropic boundary, dielectric constants greater than 1300 can be obtained along with planar couplings of about 0.50. Calcium also raises the dielectric constant, but the planar coupling level is considerably lower than that obtained with Sr. Other effects noted with Sr are a lowering of the Curie temperature, a shift in the morphotropic boundary toward the rhombohedral side, and a decrease in the distortion from cubic symmetry. In addition, Sr was found to be effective as a fluxing agent.
Phase Equilibria in the Ferrite Region of the System Fe‐Ni‐O
Authors: PALADINO A. E.
Published: June 2006

Phase equilibria in the system Fe‐Ni‐O have been investigated near NiFe2O4 up to a temperature of 1300°C. A vacuum technique has been used for determining the equilibria relations and is described in detail. The stability of spinel solid solutions up to 1300°C. in oxygen pressures of from 1 to 10−2 atmospheres has been determined.
Thermal Contraction of β‐Eucryptite‐. (Li2O.Al2O3.2SiO2) by X‐Ray and Dilatometer Methods
Authors: GILLERY F. H. , BUSH E. A.
Published: June 2006

The axial thermal‐expansion coefficients of β‐eucryptite have been measured and correlated with the volume expansion of an aggregate measured dilatometrically. A mechanical analogy to the structure of β‐eucryptite is suggested which may explain the pronounced thermal contraction in the c direction.
Concentrations of Ions at the Surfaces of Clays
Authors: TAYLOR A. W.
Published: June 2006

Equations based on the theory of the structure of the electrical double layer developed at a charged plane surface are used to calculate the concentrations of ions at the surfaces of clays suspended in various electrolyte solutions. The results indicate that in clays where the surface density of charge is high the conditions close to the surface are independent of the outer electrolyte concentration provided that this is not too high. The treatment is applied to the problem of the conditions present at the surfaces of clays suspended in dilute acid, and the effect of the addition of neutral salts on the acidity at the surface is discussed.
Effect of Heat‐Treatment on the Constitution and Mechanical Properties of Some Hydrated Aluminous Cements
Authors: SCHNEIDER SAMUEL J.
Published: June 2006

The compound compositions of four aluminous cements were determined on anhydrous as well as hydrated specimens which had been heat‐treated at temperatures between room temperature and 1400° C. Phases were identified by X‐ray diffraction and differential thermal analysis. Specimens were also tested for transverse strength, dynamic modulus of elasticity, and thermal length change. A study of the dehydration characteristics of CaO ‐ Al2O8 ‐ 10H2O3 3CaO.Al2O3. 6H2O, and Al2O3. 3H2O was included. The data indicated that CaO. Al2O3 10H2O was the primary crystalline hydrate formed in the cements at room temperature. At 50° C., 3 CaO Al2O3‐6H2O and Al2O3. 3H2O were formed as by‐products of the dehydration of CaO.Al2O3.10H2O. When heated alone in an open system, CaO.Al2O3.10H2O did not convert to 3CaO. Al2O3. 6H2O and A12O3. 3H2O. A correlation between the mechanical properties and compound compositions was noted.
The Glossmelting Process: I, A Theory of the Nature of Silicate Melts and of Their Interaction with Silica
Authors: MCKINNIS CHARLES L. , SUTTON JOHN W.
Published: June 2006

A new theory of the nature of silicate melts postulating a distribution of anionic structures is developed to account for the kinetics of the silicate melt‐silica interaction. The theory is applied to published data on the kinetics of this reaction, and correlations are made with recent viscosity studies and with commercial glassmelting practice.
Promotion of Attack on Glass and Silica by Citrate and Other Anions in Neutral Solution
Authors: BACON FRANK R. , RAGGON FRANK C.
Published: June 2006

The observation that essentially neutral solutions of sodium citrate attacked sulfur‐treated soda‐lime glass bottles of generally high chemical resistance much more than was anticipated led to a general investigation. It has been found that neutral solutions of sodium citrate attack silicate glasses and silica with a severity similar to that of substantially alkaline solutions. This effect was observed for both soda‐lime and borosilicate glasses and also for vitreous, crystalline, and amorphous forms of silica. The effect of citrate becomes perceptible at a pH of about 5 and increases rapidly with pH up to 7.6. Solutions of higher pH were not studied. Solutions of certain other complex‐forming anions show the effect on sulfur‐treated soda‐lime glass containers in varying lesser degrees. Although the active anions studied are complexing agents for alkaline earths and aluminum, it was observed that citrate had more action on a fused silica container than on containers made of certain glasses containing calcium and aluminum. Therefore a digestive action on silica and the Si–O–Si structure of glasses is to be recognized. Fluoride, the only anion tested that forms previously known complexes with silicon, had slightly less action on sulfur‐treated bottles than citrate. The results suggest that soluble silicon complexes are formed at pH values in the region of 7 by citrate and some of the other organic anions studied.
The Influence of Some Transition Elements on Visible and Infrared Transmission of Calcium Aluminate Glasses
Authors: WEIDEL ROBERT A.
Published: June 2006

A number of calcium aluminate glasses have been developed for use as infrared‐transmitting window materials. These glasses have been stabilized with respect to devitrification by introducing alkali and iron into the batch composition. The iron reduced visible transmission of these glasses and at the same time to a lesser extent tends to decrease infrared transmission as the iron concentration increases. In a study of the influence of transition elements, Mn and particularly Cu are found to increase significantly the infrared transmission of these iron‐alkali stabilized calcium aluminate glasses.
Lattice Parameters of the α‐Fe2O3‐Cr2O3 Solid Solution
Authors: Di CERBO R. K. , SEYBOLT A. U.
Published: June 2006

Lattice parameter‐composition relations are shown in the system α‐Fe2O3‐Cr2O3. This information is of some value in determining the composition of scales developed during the oxidation of alloys based on Fe‐Cr, such as stainless steels.
Strength of Synthetic Single Crystal Sapphire and Ruby as a Function of Temperature and Orientation
Authors: WACHTMAN J. B. , MAXWELL L. H.
Published: June 2006

The modulus of rupture of sapphire single crystals was determined as a function of temperature for specimens with orientations favoring plastic deformation and for specimens with unfavorable orientations. From 600°C. to l000°C., the strength of both types increased with increasing temperature, but the increase was more pronounced for the former. Ruby specimens oriented favorably for plastic deformation also showed a large increase in strength. It is conjectured that the increase in strength results from stress relief by microscopic plastic deformation.
Effect of Additives of Limited Solid Solubility on Ferroelectric Properties of Barium Titanate Ceramics
Authors: BAXTER P. , HELLICAR N. J. , LEWIS B.
Published: June 2006

An experimental survey of additives to barium titanate shows that in addition to those which are readily soluble in the barium titanate lattice (class 1) and those which are insoluble (class 2) two other distinct classes of additive, with limited solid solubility (classes 3 and 4), can be distinguished. Class 3 additives give normal ferroelectric properties with particularly low electrical and mechanical losses, as exemplified by BaTiO3 2 mole % NiTiO3 for which, after aging, tan δ= 10−3 and 1/Q = 4 X 10−4. Experimental results indicate that the ferroelectric loss, in high and low fields, is hysteresis loss associated with domain boundary movement and that in class 3 materials the losses are low because the domain boundaries are in particularly stable positions. Class 4 materials have useful dielectric properties associated with a crystallite size between 0.1 and 1 μ. For example, BaTiO3.3 mole % NaNbO3 has ε= 3200 × 200 between 0°C. and 120°C. with tan δ= 3 X 10−2. The absence of a permittivity peak is attributed to a distribution of the Curie temperatures of individual crystallites and the enhanced permittivity at lower temperatures to inhibition of the spontaneous polarization by the mutual clamping, in the ceramic, of crystallites which are too small to divide into 90° domains.
Ferrimagnetic Resonance Line Widths and Phase Distributions in Sintered Yttrium Iron Garnets
Authors: VAN UITERT L. O. , SWANEKAMP F. W. , PREZIOSI S.
Published: June 2006

Iron‐rich phases in yttrium iron garnet specimens are easily detected by microscopic examination. These phases form as pockets in the yttrium iron garnet matrix at low sintering temperatures but are swept into grain boundaries at higher temperatures. The dependence of ferrimagnetic resonance line width on composition and sintering conditions is given. Low line widths are realized when gas‐generation problems are controlled. Line widths as low as 15 oersteds have been obtained.