bluuebunny/crossref_metadata_2025 huggingface dataset:
EFFECT OF ALUMINA ON DEVITRIFICATION OF SODA‐LIME‐SILICA GLASSES*
Authors: Silverman W. B.
Published: October 2006

Abstract

The effect of the substitution of Al2O3 for the oxides of sodium, calcium, and silicon on the liquidus temperatures and phase relations has been determined for glasses lying within the composition range Na2O 11 to 19%, CaO 6 to 18%, SiO2 59 to 79%, and Al2O3 0 to 8%. The results on 137 individual determinations show that the substitution of Al2O3 for CaO permits wollastonite to be the primary phase in glasses of relatively low CaO content. As the Al2O3 content increases, the Na2O‐3CaO‐6SiO2—CaO·SiO2 boundary shifts to lower CaO contents, and the decomposition of Na2O·3CaO·6SiO2 to CaO·‐SiO2 takes place at lower temperatures. In compositions with tridymite as a primary phase, the substitution of Al2O3 for SiO2 is effective in lowering the liquidus temperature. For the composition range investigated, the SiO2‐CaO‐SiO2 and Na2O·3CaO·6SiO2‐SiO2 boundary remains at essentially the same SiO2 content for all glasses containing not more than 4% Al2O3.
SURFACE TENSIONS OF SOME OPTICAL GLASSES*
Authors: Shartsis Leo , Smock Alden W.
Published: October 2006

Abstract

The surface tension of a number of optical glasses made at the National Bureau of Standards was measured by a modification of the anchor ring method. The values for the flint glasses at 1300 °6, were in the range 210 to 230 dynes per cm., the barium crowns ranged from 260 to 310, while the other types of glasses had intermediate values. Most of the glasses had positive temperature coefficients of surface tension. The surface‐tension values increased with the increasing periods of time at which the glasses were maintained at high temperatures immediately prior to measurement. Positive rank correlation coefficients of statistical significance were found between seed quality of optical glasses and such factors as surface tension, pot attack, and amount of gas liberated during the melting process.
MECHANISM OF THERMAL‐SHOCK FAILURE IN ENAMELWARE, AN OVEN‐TEST METHOD*
Authors: Richmond J. C. , Harrison W. N.
Published: October 2006

Abstract

Enameled utensils were tested for thermal‐shock resistance by heating in an oven to a predetermined temperature, then quenching with iced water. This process was repeated, following a schedule of successively higher temperatures from 375° to 600°F. until the specimens chipped or withstood heating after the tenth quench. The method is suitable for testing most sizes and shapes of utensils. Data on a wide variety of commercial utensils are included.

Photographs show that failures originate in cracks formed during quenching from stresses produced by rapid cooling and shrinking of the surface of the enamel. The chips are usually blown off with considerable force during heating following the quench by steam produced from water which penetrated the cracks during the quench. Evidence is presented that deformation of the pan bottom during heating does not produce thermal shock failures.
SELENIUM‐RUBY AND OTHER GLASSES COLORED BY SELENIUM*
Authors: Pavlish A. E. , Austin C. R.
Published: October 2006

Abstract

Data are presented on the development and production of ruby and other colors in glass by employing selenium as one of the colorants. The addition of 0.25% of powdered selenium and 0.30% of metallic cadmium with 0.055% of silicon as the reducing agents in a zinc‐free glass produced good ruby color. The addition of both oxidizing and reducing agents showed that conditions most favorable for the retention of selenium had an adverse affect on the retention of cadmium.

The results of day‐tank trials embodying the principles found in this work are listed.
REACTION OF CLAYS WITH ORGANIC CATIONS IN PRODUCING REFRACTORY INSULATION*
Authors: Grim R. E. , Allaway W. H. , Cuthbert F. L.
Published: October 2006

Abstract

Slips prepared in certain ways with some organic compounds shrink only slightly after casting so that their shape and porosity are not lost on drying or later firing. This provides a possible method of producing refractory insulation without final sawing to shape. The compounds effective in producing such porous clay bodies are certain amines or other organic cations, in which one or more large hydrocarbon groups are attached to the basic nitrogen atom. The results of studies concerned with molding and other problems connected with production of insulating refractories by this process are given.
CONCENTRATION AND DETERMINATION OF GRADE IN TESTS ON SILLIMANITE IN IDAHO SCHIST*
Authors: Skinner Kenneth G. , Kelly Hal J.
Published: October 2006

Abstract

Laboratory batch tests have demonstrated that the Idaho sillimanite schist was amenable to beneficiation by common ore‐dressing methods. The minable schist, containing an average of about 7.8%, sillimanite, was crushed to pass 35 mesh and concentrated by a combination of tabling and flotation.

Grade was determined by petrographic examination of fractions obtained by heavy‐liquid separations in a centrifuge. This method was used as a positive means of separating the sillimanite from the gangue minerals.

Photomicrographs illustrate the character and quantity of sillimanite in the various concentration products.
CHANGES IN DISTILLED WATER STORED IN GLASS AMPULS*
Authors: Hinson A. L. , Smith D. C. , Greene J. F.
Published: October 2006

Abstract

Ampuls of distilled water were stored for a period of two years, with and without a preliminary autoclaving. Solids picked up by the water were found in most cases to increase steadily for the duration of the storage period while the pH tended to reach a constant value characteristic for each glass. Figures are given for the pH increase and solids pickup of all the available glasses known to have been used for ampuls in this country.
EFFECT OF EXCHANGEABLE CATIONS ON HYDROPHILIC NATURE OF KAOLIN AND BENTONITE*
Authors: Siefert A. C. , Henry E. C.
Published: October 2006

Abstract

The affinity for water of a kaolinite‐type clay (kaolin) and a montmorillonite‐type clay (bentonite), saturated with hydrogen, calcium, sodium, and potassium, was studied by three methods, namely, heat of wetting as determined by calorimetric measurements, sorption of water from the vapor phase by weighing, and desorption or removal of water by differential‐thermal analysis. It was shown that hydrogen and calcium clays had a greater affinity for water than sodium and potassium clays. Although the bentonite evolved more heat and sorbed more water per gram of clay, it evolved less heat and sorbed less water per milliequivalent of exchangeable cation than did the kaolin; the differences in the effects of various cations were more pronounced in bentonite than in kaolin. The results may be explained as follows from considerations of the mineral structures: (1) A greater amount of water hydrates the surface of kaolinite in proportion to that hydrating the exchangeable cations than is the case in montmorillonite and (2) the exchangeable cations may be hydrated to a greater degree (i.e., less strongly held) on kaolinite than on montmorillonite.
INFLUENCE OF GLASS COMPOSITION ON REDUCIBILITY OF Ag+, Bi3+, Sb3+, AND PP+*
Authors: Bastress Alfred W.
Published: October 2006

Abstract

The reducibility of a number of ions by dry hydrogen was studied in various glass compositions. Reduction temperatures with dry hydrogen were about 75° C, lower than with wet hydrogen. The glasses contained 5.0% of Sb2O3, Bi2O3, or PbO or 0.1% of Ag2O. In all of the glasses, silver ions were reduced at lower temperatures as basicity was increased, while an increased ratio of B3+ to O2‐ or Si4+ to O‐ increased stability. The reducibility of Bi3+, Sb3+, and Pb2+ are not easily interpreted. Silver showed reduction at approximately 130°C., bismuth at 200°C., lead at 350°C., and antimony at 400°C.
RECRYSTALLIZATION OF BERYLLIUM OXIDE BODIES AT 2000°C.*
Authors: Duwez Pol , Odell Francis , Taylor Jack L.
Published: October 2006

Abstract

Recrystallization is an important factor in the preparation of very dense pure oxide ceramic bodies. The work described in this paper shows the effect of the original particle size on the degree of recrystallization of beryllium oxide bodies. A water elutriator for particle‐size separation in the subsieve range and an oxyacetylene furnace with zirconia refractories for operation at 2000°C. are described. The microscopic examination of prepared thin sections and the X‐ray diffraction back‐reflection method are used to determine particle sizes and the degree of recrystallization. Shrinkage during firing is found to be approximately constant for all particle sizes originally below 10 microns and decreases in a regular manner with increasing particle size. The recrystallization factor for beryllium oxide is found to vary from 40 for 1.25‐micron particles to 2.5 for 10‐micron particles.
STUDY OF ADHERENCE OF MOLTEN GLASS TO HEATED METALS*
Authors: Kapnicky J. A. , Fairbanks H. V. , Koehler W. A.
Published: October 2006

Abstract

A kinetic test for evaluating the adherence of molten glass to metal was devised. The results are expressed in terms of the highest metal temperature at which a drop of molten glass shows no adherence. This temperature was determined for several cast irons and nonferrous metals and alloys. It was found that this temperature was affected by the structure and surface roughness of the metals investigated. The effects of cyaniding, carburizing, nitriding, quenching, and annealing were determined. The general effect of mold lubricants on the adherence temperature is indicated.
PROPERTIES OF SOME SUBSTANCES ISOSTRUCTURAL WITH SILICA*
Authors: Hummel F. A.
Published: October 2006

Abstract

Quartz and cristobalite types of AlPO4 were prepared in a pure condition and compared with silica regarding thermal behavior. The thermal expansion of the cristobalite type of AlPO4 is remarkably similar to that of cristobalite, indicating a close structural relationship at elevated temperatures as well as at room temperature. The temperature of inversion of the cristobalite type of AlPO4 apparently depends on previous thermal history, as in the case of cristobalite, but the presence of a double endothermic peak during the low‐high inversion may indicate that the mechanism is different from that involved in the low‐high cristobalite transition. Data on the thermal expansion of the network structures NaAlSiO4 (carnegieite) and Na2CaSiO4 are presented and are discussed in the light of the known structural relationships in the series high cristobalite, high carnegieite, and Na2CaSiO4.
GLAZES FOR ZIRCON PORCELAINS*
Authors: Luttrell Carolyn Banks
Published: October 2006

Abstract

An investigation was conducted to develop a white opaque low‐expansion glaze of suitable gloss and texture for commercial application on zircon porcelain. A glaze containing the alkaline‐earth zirconium silicates was selected as the base glaze; batch changes and molecular adjustments were then made. On a molecular basis the KNaO content should be low (less than 0.20 equivalent); the alkaline‐earth oxides should be used to raise the RO group to 1.00. High MgO (from 0.40 to 0.50 equivalent) definitely reduces crazing tendencies; CaO and ZnO complete the RO group. The most desirable Al2O3 and SiO2 content is 0.3 to 0.4 and 3.0 to 4.0 equivalents, respectively. The Al2O3‐SiO2 ratio considerably affects the finish and texture of the fired glaze. From 0.5 to 0.7 equivalent of ZrO2 gives satisfactory opacity and improves crazing resistance; B2O3, although important as a low‐expansion constituent, is limited to 0.2 equivalent. The compositions of glazes applicable to typical zircon porcelain bodies are given.
BACTERIA, A FACTOR IN SLIP CONTROL*
Authors: Johnson A. L. , Postlewaite D. E. , Rittenberg† S. C.
Published: October 2006

Abstract

An analysis of the significance of bacteria as a factor in slip control based on actual plant experiences is given. It is shown that variations of some magnitude in the properties of casting slip can occur as a result of bacterial action.
EFFECTS OF MAJOR AND SOME MINOR CONSTITUENTS ON GLASSMELTING*
Authors: Enright Dorothy P. , Marshall Paul A. , Poole James P.
Published: October 2006

Abstract

The effects of the major and some minor constituents on the melting and fining characteristics of amber and flint container glasses are discussed. The constituents investigated were silica, alumina, lime, magnesia, soda, fluorine, barium oxide, and sulfates. The effects were measured by seed count, visual analysis, and low‐temperature viscosity. Curves of fining time and low‐temperature viscosity characteristics are presented
SURFACE STRUCTURE AND SURFACE PROPERTIES OF CRYSTALS AND GLASSES*
Authors: Weyl W. A.
Published: October 2006

Abstract

Experiments concerning the influence of asymmetrical units on the surface properties of glasses, sponsored by the Mechanics and Materials Branch of the Office of Naval Research, led to a better understanding of the surface structure of crystalline solids A picture is advanced which indicates a close similarity between the atomic structure of the surface layer of a crystal and that of a glass. Common to both are certain characteristic features, namely, the inconstancy of (a) the coordination number, (b) the inter‐nuclear distances, and (c) the bond angles.

The difference between the surface structure and the interior of a crystal depends on the polarization properties of the ions A schematic representation of the distribution of bond strength in ideal and real crystals, in glasses, and in surface films brings out the similarity between the surface of crystals and the structure of glasses.

Based on this picture, a number of apparently unrelated phenomena are discussed and explained: (1) devitrification of the glass surface, (2) effect of imperfections on the transformation of crystals (silica brick), (3) sinteririg of highly refractory oxides. (4) dielectric constant of polycrystalline materials, and (5) electric absorption of stratified dielectrics
BEHAVIOR OF FIRED‐CLAY RING SECTIONS UNDER LOAD*
Authors: Everhart J. O.
Published: October 2006

Abstract

The advent of the electric strain gauge has made it possible to study the behavior of ceramic materials under load, and their stress‐strain relations may be determined with exactness. Earlier work by Lassettre and Everhart has shown that ceramic materials are elastic and that mathematical and engineering formulas may be applied to their use. This paper is concerned with the theoretical analysis of stresses in ring sections and with the behavior of fired ceramic ring sections, such as sewer pipe and drain tile, under stress.

Data are presented which show that fried ceramic pipe almost precisely follow the behavior predicted from theoretical calculations such as those first presented by Talbot in 1908. A new precise equation for calculating relations between diameter, wall thickness, and strain is presented, and the validity of shorter semiempirical formulas commonly used is examined in the light of the more precise knowledge. Examples of the use of these mathematical formulas for changing relationships between diameter and wall thickness are given. Some manufacturers of sewer pipe have already changed their dies to give the different relationships, with successful results.
DEVELOPMENT OF A PORCELAIN VACUUM TUBE*
Authors: Hursh R. K.
Published: October 2006

Abstract

A satisfactory vacuum tube for the betatron was produced from porcelain by the casting process. The tube is toroidal in form with two tubular arms to which glass connections are fused for the sealed‐in electrical leads. The interior of the tube has a metallic electrically conductive coating. The tube is permanently sealed off with a high vacuum.
HYGROSCOPICITY OF SODA‐LIME‐SILICA CONTAINER GLASSES*
Authors: Matson Frederick R.
Published: October 2006

Abstract

Powdered‐glass samples were exposed to an atmosphere of 98% relative humidity at 100°F. for three days. Commercial bottles and laboratory melts which systematically covered the field of container compositions were tested. The resulting gain in weight of the glasses, which is a function of their chemical compositions, can serve as an accelerated test of the rate of attack by water vapor. The determination of the permanent gain in weight of the treated samples after they have been dried and the appearance of the products formed on the surface of the glass powders provide further useful data.
SOME EFFECTS OF ZINC AND CARBON MONOXIDE ON FIRE‐CLAY REFRACTORIES*
Authors: Patrick R. F. , Sosman R. B.
Published: October 2006

Abstract

No experimental proof could be obtained that zinc has any disintegrating action on blast‐furnace fire‐clay brick. Zinc and zinc oxide, however, act as mild catalysts for the decomposition of carbon monoxide to form carbon dioxide and carbon, a reaction which has been abundantly proved, when catalyzed by iron, to be a prime cause of disintegration of fire‐clay brick. The carbon deposited by the reaction is crystalline graphite.
CRYSTALLOGRAPHIC INVERSIONS OF THE ALUMINUM ORTHOPHOSPHATE POLYMORPHS AND THEIR RELATION TO THOSE OF SILICA*
Authors: Beck Warren R.
Published: October 2006

Abstract

The temperature‐stability relationships of the AlPO, polyrnorphs have been studied by X ray, thermal analysis, and thermal expansion. The system parallels that of silica very closely. Following is a diagrammatic representation of the findings for AlPO4: Conversions from one form to another are shown to be much more rapid than for corresponding silica cases. Furthermore, the temperatures, with the exception of the berlinite inversion. are all lower than for corresponding silica temperatures.
PHOSPHATE GLASS: PbO‐WO3‐P2O5 SYSTEM*
Authors: Rothermel Joseph J. , Sun Kuan‐Han , Silverman Alexander
Published: October 2006

Abstract

The glass‐formation region has been determined for the PbO–WO3–P2O5 system ‡ and certain physical properties of representative glasses have been measured. Glasses of the system show an unusually high X‐ray and gamma‐ray absorption and are not readily discolored when exposed to X rays. Equations have been developed from which specific volumes and lead equivalents may be calculated from composition. Because of their high index of refraction and relatively low dispersion these glasses are also useful for optical purposes.
SPOT TEST FOR CHEMICAL RESISTANCE OF ENAMELED SURFACES*
Authors: Roberts J. T.
Published: October 2006

Abstract

A theoretical relationship between the color and thickness of thin films of amorphous silica was established. An acid‐resistance test based on this relationship was developed and applied in the testing of enamelware.

According to the results obtained thus far, the color changes that are actually brought about by chemical attack agree with those which should occur theoretically. The test method thus appears to be fundamentally sound, at least insofar as this point is concerned.

Its application in the testing of an enamel at different temperatures, as well as in the testing of various types of enamels at constant temperature, appears to afford satisfactory results. Enamel No. 41, when exposed for 48 hours to a solution of 20% hydrochloric acid at 60°F., developed according to this method of test a film about 675 a.u. thick. At 100°F. the film reached a thickness of about 2550 a.u. In the constant‐temperature tests the various types of enamels developed films in two hours that ranged from 60 to 2750 a.u. in thickness.
REACTIONS OF BeO AND SiO2; SYNTHESIS AND DECOMPOSITION OF PHENACITE*
Authors: Morgan R. A. , Hummel F. A.
Published: October 2006

Abstract

Reactions of pure BeO and SiO2 were investigated at temperatures ranging from 1300° to 1700 °C. The synthesis and decomposition of phenacite were studied using willemite as an additive. A phase diagram is tentatively proposed on the basis of data obtained.
NOTES ON SILICATE ANALYSIS: II, DETERMINATION OF ZINC*
Authors: Osthaus B. B.
Published: October 2006

Abstract

In silicate analysis, quinaldic acid is more selective than 8‐hydroxyquinoline or 8‐hydrosyquinaldine as a reagent for zinc in the presence of aluminum, titanium, iron, calcium, and magnesium. Zinc can be separated from these metals and the filtrate used for their determination without interference from an excess of quinaldic acid.
FURTHER FACTORS INVOLVED IN PRODUCTION OF THIN WALL TILE*
Authors: Lindquist C. Alan , Campbell R. M.
Published: October 2006

Abstract

Warpage tendencies of thinner wall tile were considered, and the practicability of producing wall tile 1/8 in. thick was investigated. The maximum permissible warpage was taken as 0.4%, which corresponds to the allowable warpage in the Simplified Practice Recommendation of the National Bureau of Standards. Wall tile 1/8 in. thick were produced successfully from both high‐talc and high‐pyrophyllite bodies. A unique method of measuring the warpage of wall tile is presented, which may have considerable application.
DISTRIBUTION OF HEAVY‐METAL IONS IN SILICATES CONTAINING SEVERAL ANIONS OF DIFFERENT SIZE*
Authors: Forland T. , Weyl W. A.
Published: October 2006

Abstract

A study of the color of minerals revealed that cobalt blue, the most common blue colorant in glasses, glazes, ceramic pigments, and synthetic minerals, seems to be almost completely absent in the mineral kingdom. This observation led to an investigation of the conditions under which the CoO4 groups form and to the composition of natural cobalt minerals. It was found that minerals containing Co2+ ions surrounded by oxygen must have formed generally at low temperature and that the cobalt was removed from the magma when the crystallization of silicates, aluminosilicates, and aluminates began. To explain this phenomenon, the distribution of heavy‐metal ions in silicate melts containing anions of different size was examined by means of model experiments.

It could be demonstrated that these anions are statistically distributed around the heavy‐metal ions as long as the thermal energy is high and the interionic distances are large. With decreasing temperatures the statistical distribution changes into one that is governed by two energy terms, one resulting from the Coulomb forces, the other from the mutual polarization of the ions.

On the basis of Fajans' theory of the deformation of ions it was possible to explain the formation of sulfidic ores from the original magma and the striking of glasses of the CdS type.
STUDY OF EFFECT OF CATION CONCENTRATION AND SIZE ON HELIUM PERMEABILITY OF ALKALI‐SILICA GLASSES*
Authors: Newkirk Terry F. , Tooley F. V.
Published: October 2006

Abstract

A study was made of the effect of systematic variations in the alkali‐cation concentration and size on the permeability of alkali‐silica glasses to helium at 300°C. Permeability determinations were made on fused silica, Pyrex‐brand chemical glass, Na2O‐SiO2 glasses containing 20, 25, and 30 mol % Na2O, a K2O‐SiO2 glass containing 30 mol % K2O, and a Li2O‐Na2O‐SiO2 glass containing 5 mol % Li2O and 25 mol % Na2O.

Additions of Na2O to SiO2 glass produced a rapid decrease in the permeability of the glass. The permeability was found to decrease exponentially over the range 0 to 30 mol % Na2O. The substitution, atom for atom, of potassium for sodium increased the permeability of the glass, whereas lithium in combination with sodium decreased the permeability as compared with the soda glass. This was attributed primarily to the difference in the polarizing power of these cations that affected the ionic radius of the surrounding oxygens and resulted in a change in the packing density of the ions in the glass.

A comparative packing index was calculated for the glasses based on the percentage of the absolute volume of glass contributed by the constituent elements. For the Na2O‐SiO2 glasses, increase in packing index (indicating a more closely packed structure) was accompanied by a decrease in permeability. It is suggested that (1) the comparative packing index is a potentially valuable index of permeability only for glasses containing the same atoms, (2) new atoms introduce a new polarizing factor in the glass, and (3) the packing index ceases to be comparative for the two glasses.
FUNDAMENTAL STUDY OF CRYSTALLINE AND GLASSY PHASES IN WHITEWARE BODIES*
Authors: Tuttle Milton A. , Cook Ralph L.
Published: October 2006

Abstract

A rapid and sensitive method for the quantitative determination of the crystalline constituents in kaolin‐flint‐feldspar blends has been developed with the Geiger‐counter X‐ray spectrometer. Two variations of this method were the use of (1) a powdered sample with a reference‐material addition and (2) a polished normal body surface. The powdered‐sample technique with a reference‐material addition showed the greater accuracy and consistency of results. The polished‐surface technique was slightly less accurate, but the preparation and nature of the test specimen make it very adaptable to control methods. With this technique the complete preparation and testing of the fired surface can be carried out in approximately 10 minutes. Standardization curves for the X‐ray spectrometer technique were used to obtain quantitative information concerning the crystalline constituents in the following blends: (1) kaolin‐flint, (2) kaolin‐feldspar, (3) flint‐feldspar, and (4) kaolin‐flint‐feldspar, as well as with additions of 1.2 and 2.8% lime and magnesia, and direct substitution of nepheline syenite for feldspar. Pressed 1 1/2‐in. pellets of each body were subjected to 3‐ and 12‐hour soaking periods at 1200° and 1400°C. Quartz, mullite, cristobalite, and wollastonite were identified as the crystalline constituents in the kaolin, flint, and feldspar blends studied. Quantitative X‐ray information concerning the reduction of the free‐quartz content, formation of cristobalite and mullite, and the amount of the total crystalline content was used to determine the effects of variations in composition and heat‐treatment for the different blends.
TESTING OF CLAYS FOR LIGHTWEIGHT AGGREGATE*
Authors: Klinefelter T. A. , Hancock Robert T. , Hamlin Howard P.
Published: October 2006

Abstract

A method of testing and evaluating clays suitable for the production of lightweight aggregate is presented. The procedures to be used with both the laboratory furnace and the pilot‐plant rotary kiln are outlined, and the determinations and tests necessary for relative comparisons of the products are described.
EFFECTS OF SOME ELECTROLYTES ON COLOR VALUE OF ENAMELS MADE FROM A STANDARD TITANIA‐OPACIFIED FRIT*
Authors: Marbaker Edward E. , Saunders Hollis S. , Baumer Leon N.
Published: October 2006

Abstract

Just as the properties of titania enamels are influenced by the clay used as the suspending agent in slip preparation, so it was thought that the salts used as electrolytes might also have effects of a similar nature. Six salts, KCl, K2CO3, NaAlO2, NaNO2, MgCO3, and KNO3, more or less commonly used as electrolytes for setting up titania enamels, were employed singly and in combinations of two and three in the preparation of 25 slips made from a standard frit. The clay content was 4%, and the milling conditions were constant. Slips, therefore, that varied in electrolyte content only were sprayed on ground‐coated steel plates, which were then fired uniformly. The set of the slips was determined by means of the Irwin slump test and the Brookfield viscometer. The reflectance, color value, finish, and acid resistance of the enamels were found by standard methods. The results showed that electrolytes have much more effect on enamel properties than has commonly been supposed and that, in the preparation of enamels, not only the quality of the frit but the properties of the components of the mill addition, clay and electrolyte alike, merit careful consideration in order to achieve the best possible results.
High‐Temperature Defect Structure of Iron‐Doped α‐Alumina
Authors: DUTT B. V. , KRÖGER F. A.
Published: October 2006

Conductivity measurements of iron‐doped a‐Al2O3 by Pappis and Kingery are interpreted on the basis of a model in which ionic defects are the major defect species. The analysis leads to equilibrium constants for the establishment of non‐stoichiornetry in Al2O3 and for the oxidation‐reduction of divalent to trivalent iron, and to the position of the electronic level of Fe2+ (=FeA1′) in the gap at Er+ 3.66 eV.
Additive and Impurity Distributions at Grain Boundaries in Sintered Alumina
Authors: JOHNSON W. C. , STEIN D. F.
Published: October 2006

Additive and impurity distributions at grain boundaries in sintered Al2O3 were determined using a scanning Auger microprobe, transmission electron microscopy, metallography, and electron probe analysis. The results indicated that Ca was present uniformly at the boundaries as a segregant, whereas the Mg or Ni levels observed resulted from nonequilibrium spinel particles. The Ca concentrations were consistent with equilibrium segregation theory and followed an equilibrium segregation isotherm.
Phases in the System NaAlO2‐Al2O3
Authors: ELLIOT A. GRANT , HUGGINS ROBERT A.
Published: October 2006

Mixed oxide powders prepared by ashing filter paper soaked in aqueous salt solutions were heat‐treated in the range 800° to 1150°C. Compositions spanning the range NaAlO2 to pure Al2O3 were examined. A phase with the mullite structure, λ‐Na2O ·xAl2O3 with x varying from 3 to ≊ 12, and a new hydrated form of sodium aluminate, ρ‐Na2O · Al2O3· 6H2O, were found. The stability ranges and decomposition behavior of these materials were determined. A K analog to the A phase was also found.
Sintering Mechanisms in Thoria Gel
Authors: BANNISTER M. J.
Published: October 2006

Isothermal sintering experiments were combined with measurements of crystallite size distribution and BET surface area in a study of the sintering mechanisms in thoria gel. The results suggest that crystallites in the gel have a coordination number of ∼5 and sinter together by a grain‐boundary diffusion mechanism.
Composition and Conductivity of Tin Oxide Films Prepared by Pyrohydrolytic Decomposition of Tin(IV) Compounds
Authors: KIM HASUCK , LAITINEN H. A.
Published: October 2006

The conductivity of thin poly crystalline Sn oxide films prepared by spraying solutions of Sn(IV) compounds onto glass or quartz substrates was studied. Conductivity was decreased by increasing the temperature or prolonging the time of heating after hydrolysis, by substituting SnBr4 for SnCl4, and by substituting O2 for N2 during spraying. These effects are explained in terms of nonstoichiometry of the sample and the presence of residual halogens in the crystal lattice as detected by ion‐probe analysis.
Hot‐Working of Aluminum Oxide: II, Optical Properties
Authors: RHODES W. H. , SELLERS D. J. , VASILOS T.
Published: October 2006

Polycrystalline Al2O3 fabricated into plates or shapes by hot‐working techniques exhibits high in‐line transmittance from 0.4 to 5.5 μm. Examination of the product by an inverse pole figure technique demonstrated a strong {0001} texture normal to the pressing direction for both equiaxed and textured microstructures. The crystallographic texture was attributed to the dominance of basal slip in deformation. A comparison of transmissivity in the 2 principal directions of a forged plate strongly suggested that a reduction of birefringence resulting from the crystallographic texture was partially responsible for the high transmissivity. The absorption coefficient at 4.5 μm was 0.15 mm‐1, ∼ that for sintered Al2O3 and 5 times that for sapphire
Effect of Melting History on the Mechanical Properties of Glass: II, Effects of Raw Materials and Bubbling Gases Through the Melt*
Authors: SPROULL JAMES F. , RINDONE GUY E.
Published: October 2006

Powdered premelted end‐member glasses were mixed in equimolar quantities to yield the composition 0.5Li2O· 0.5K2O·2SiO2. The pristine strength of glass rods drawn from melts of this mixture showed the same relation to melting history and to microphase size as that of the glass melted from batch as reported in Part I of this paper. No conclusive differences in strength were found when alkali nitrates were used instead of alkali carbonates. Bubbling dry O2 into the melt increased the strength, as did melting in dry O2, but much more rapidly. Although bubbling with dry Ar increased the strength rapidly at first, a very drastic and sharp decrease followed.
Transformational Plasticity in Bi2O3
Authors: JOHNSON C. A. , BRADT R. C. , HOKE J. H.
Published: October 2006

Transformational plasticity associated with the monoclinic‐to‐cubic phase transition at 730°C in Bi2O3 was observed and characterized. This phenomenon is explained in terms of Greenwood and Johnson's model of internal stress‐induced deformation, proceeding, in this instance, by a time‐dependent, grain‐size‐sensitive creep mechanism, probably grain‐boundary sliding. Criteria are proposed for choosing other prospective transformationally plastic ceramics; they are met by Bi2WO6, which also exhibits extensive transformation plasticity.
Application of Spectral Remote‐Sensing Method for Recovering Temperature Distribution in Glass
Authors: HOMMERT P. J. , VISKANTA R. , CHUPP R. E.
Published: October 2006

A method for recovering the temperature distribution in glass from remotely sensed spectral emission data was studied. The temperature distribution, which was related analytically to the spectral emerging intensity, was determined by an optimization technique that minimizes the difference between measured and calculated emissions. The method was evaluated by measuring spectral emission from heated glass using both a spectrometer and a spectroradiometer. Data were taken from 600 to 900 K for window glass samples with different back‐surface boundary conditions. The recovered temperature profiles obtained using data from both measuring instruments were compared with each other and with temperature profiles predicted from a combined conduction‐radiation heat‐transfer analysis. When only 2 unknown coefficients were used to represent the temperature distribution, the recovered and predicted profiles agreed within 1%.
Effects of Crystal‐Lattice Distortion on Optical Transmittance of the (Pb, La)(Zr, Ti)O3, System
Authors: MIYAUCHI KATSUKI , TODA GYŌZŌ
Published: October 2006

Optical transmittance and crystal‐lattice distortion and their relation were studied in hot‐pressed La‐doped Pb zirconate‐titanate (PLZT) ferroelectric ceramics at the ferroelectric‐antiferroelectric morphotropic phase boundary. In the thermally annealed condition, the crystal system of PLZT at the FE‐AFE morphotropic phase boundary was pseudotetragonal and similar to the antiferroelectric phase (AFEβ) appearing in Pb(Zr, Ti)O3 and (Pb, Sr)ZrO3. Optical transmittance and crystal‐lattice distortion change monotonically with respect to the Zr/Ti ratio, and the optical transmittance increases approximately linearly with decreasing lattice distortion. In view of these relations and the temperature dependence of the optical transmittance, it is suggested that light scattering in PLZT ceramics is caused mainly by the variation in refractive index encountered as the light travels from one domain or grain into another.
Arc‐Imaging Technique for Measuring High‐Temperature Thermal Conductivity and Diffusivity of Refractory Oxides
Authors: FAUCHER M. , CABANNES F. , ANTHONY A. M. , PIRIOU B. , SIMONATO J.
Published: October 2006

An imaging technique was developed for measuring the thermal conductivity and diffusivity of small disks of refractory oxides at temperatures ranging from 1500°K to the melting point of the material. One face of the sample is exposed to the radiant heat flux of an arc‐imaging furnace. A shutter instantaneously cuts off incident radiation, and the cooling of the specimen is recorded with a motion‐picture camera. The flux re‐radiated by the nonirradiated face of the sample is measured with a thermopile. Thermal conductivity and temperatures in the bulk of the sample are determined by computational analysis. Experimental data are fitted to computed cooling‐temperature curves to determine thermal diffusivity. This technique was applied to pure and stabilized ZrO2, Y2O3, and ThO2.
Phase Equilibria in the System Si3N4‐SiO2‐BeO‐Be3N2
Authors: HUSEBY IRVIN C. , LUKAS HANS L. , PETZOW GÜNTER
Published: October 2006

The 1780°C isothermal section of the reciprocal quasiternary system Si3N4‐SiO2‐BeO‐Be3N2 was investigated by the X‐ray analysis of hot‐pressed samples. The equilibrium relations shown involve previously known compounds and 8 newly found compounds: Be6Si3N8, Be11Si5N14, Be5Si2N6, Be9Si3N10, Be8SiO4N4, Be6O3N2, Be8O5N2, and Be9O6N2. Large solid solubility occurs in β‐Si3N4, BeSiN2, Be9Si3N10, Be4SiN4, and β‐Be3N2. Solid solubility in β‐Si3N4 extends toward Be2SiO4 and decreases with increasing temperature from 19 mol% at 1770°C to 11.5 mol% Be2SiO4 at 1880°C. A 4‐phase isotherm, liquid +β‐Si3N4 (ss)Si2ON2+ BeO, exists at 1770°C.
Precipitation Studies in the System WC‐Tic
Authors: BRUN M. K. , NEURGAONKAR R. R. , STUBICAN V. S.
Published: October 2006

The solubility of WC in TiC was found to vary from 50 mol% at 2050°C to 75 mol% at 2350°C; WC was precipitated from solid solutions containing 75 mol% WC‐25 mol% TiC and 65 mol% WC‐35 mol% TiC at 1900°C. The precipitated WC occurred as well‐aligned ribbon‐shaped particles. The crystallographic orientation of the precipitate and the matrix established by electron diffraction techniques is [100]WC[110]TiC and [010]WC[001′]TiC. The interfacial planes were (001) for WC and (111) for TiC solid solution. Diffraction spot splitting occurred for all reflections of precipitated WC except the 001 type, indicating that compression of WC along the [110] direction took place, resulting in an apparent orthorhombic symmetry. This phenomenon was explained on the basis of the specific volumes and the difference in thermal expansion coefficient between WC and the solid solution. Tungsten carbide precipitated rapidly in the presence of Co, with all the WC precipitating in the form of platelets randomly oriented around the matrix grains. The hardness of the solid solutions 65 mol% WC‐35 mol% TIC and 75 mol% WC‐25 mol% Tic increased ∼10% and ∼23%, respectively, after they were annealed at 1900°C.
Finite Element Techniques Applied to Cracks Interacting with Selected Singularities
Authors: CONWAY JOSEPH C.
Published: October 2006

The finite‐element method for computing the extensional stress‐intensity factor, K1, for cracks approaching selected singularities of varied geometry is described. Stress‐intensity factors are generated using both displacement and J‐integral techniques, and numerical results are compared to those obtained experimentally in a photoelastic investigation. The selected singularities considered are a colinear crack, a circular penetration, and a notched circular penetration. Results indicate that singularities greatly influence the crack‐tip stress‐intensity factor as the crack approaches the singularity. In addition, the degree of influence can be regulated by varying the overall geometry of the singularity. Local changes in singularity geometry have little effect on the stress‐intensity factor for the cases investigated.
Influence of Microstructure on Crack Propagation in ZnSe
Authors: FREIMAN S. W. , MECHOLSKY JOHN J. , RICE ROY W. , WURST J. C.
Published: October 2006

The rate of crack propagation as a function of the stress intensity factor, K1, for chemically vapor‐deposited (CVD) ZnSe was significantly larger in H2O than in air. Lower flexural strengths were measured in H2O (29 MN/m2) than in air (40 MN/m2). Fracture surface analysis of these flexural specimens showed that failure usually resulted from flaws contained within 1 or 2 large grains. These flaws were shown to propagate at a stress‐intensity factor of 0.33 MN/m3/2 compared to the measured value of 0.70 MN/m3/2 for polycrystalline ZnSe. Fracture mechanics parameters obtained in the present study were used to show that failure time predictions using values of K1C for propagation through a single grain are 25 times shorter, and proof‐to‐service stress ratios are 1.1 times greater, than those obtained for polycrystalline ZnSe.
Surface Texture Formation in Al2O3 Substrates
Authors: NAKADA Y. , SCHOCK T. L.
Published: October 2006

Crystallographic texture formed at the surface during the sintering of 3 tape‐cast Al2O3 substrates was studied as a function of sintering temperature and atmosphere. The sintering atmosphere strongly influenced the surface texture formed. A strong (001) basal‐plane fiber texture normal to the plane of the substrate is produced when commercial green substrates are sintered in air at 1600° to 1700°C; sintering in vacuum (< 2 × 10‐6 mm Hg) or dry H2 produces a weaker texture. Grain growth is a necessary but insufficient condition for the formation of a strong surface texture. It is proposed that surface texture formation is caused by an excess driving force which results in growth of grains with a low‐surface‐energy plane exposed at the substrate surface. Since the surface energy of a crystallographic plane is a function of atmosphere and impurities adsorbed on the surface, both these factors should have a pronounced effect on surface texture formation, as observed in the present study.
Interdiffusion in Semiconducting Oxide Solid Solutions
Authors: COOPER A. R.
Published: October 2006

Previous workers have used the Darken equation to describe Interdiffusion in NiO‐CoO. It is shown that, for this equation to be appropriate, not only is a mobile nonionic charge carrier required, but also it is necessary to create cation and anion lattice sites on one side of the couple and destroy them on the other. To achieve this result and conserve oxygen requires transport of oxygen relative to the lattice. It is suggested that oxygen interstitial diffusion provides a likely means of transport with is consistent with the observation that the interdiffusion does not depend on specimen thickness.
Ba2Ti9O20 as a Microwave Dielectric Resonator
Authors: PLOURDE J. K. , LINN D. F. , O'BRYAN H. M. , THOMSON JOHN
Published: October 2006

Microwave measurements of Ba2Ti9O20 show that this ceramic is uniquely suited for dielectric resonators. (Suitable ceramics should have a high dielectric constant K, a low dielectric loss (high Q), and a low temperature coefficient of resonant frequency, τ.) At 4 GHz, Ba2Ti9O20 resonators have Q >8000, K= 39.8, and τ=2 ppm/°C. Measurements of Q and τ were made on unmetallized ceramic resonator disks positioned in a waveguide; K was measured using a dielectric post resonator technique. From 4 to 10 GHz, Q approaches that for a copper waveguide cavity, whereas the temperature coefficient is typically 8 times lower.
Pyroelectric Response in Transparent Ferroelectric Glass‐Ceramics
Authors: LAYTON M. M. , SMITH J. W.
Published: October 2006

When the network system is limited, most ferroelectric glass‐ceramics will produce a fully crystallized transparent body when cerammed at low temperatures. Higher‐temperature heat treatment results in crystal growth and gradual loss of transparency. In the transparent state, the crystal size is limited to ∼2000 Å. Piezoelectric and hysteresis loop measurements have failed to detect evidence of ferroelectricity, but the present pyroelectric measurements show that fully transparent glass‐ceramics can be ferroelectric.
Interdiffusion in the CaF2‐YF3 System
Authors: VISSER R. G. , SCHIAVI W. F. , BERARD M. F.
Published: October 2006

An electron microprobe interdiffusion study was made in single crystals between 1200° and 1331°C over the solid‐solution compositional range 0 to 20 mol% YF3 in CaF2. At constant temperature, the value of δ, the interdiffusion coefficient, increased approximately exponentially with increasing YF3 content. As YF3 content increased, the temperature dependence of δ decreased. Extrapolation of δ to 0% YF3 combined with consideration of the defect formation mechanism at mite dilution allowed estimation of the impurity diffusion coefficient for Y in essentially pure CaF2.
Grain‐Boundary Diffusion of U in Pure and Doped Uranium Carbides with Different C/U Ratios
Authors: ROUTBORT J. L. , MATZKE Hj.
Published: October 2006

“The grain‐boundary diffusivity of U in UC was measured between 1200” and 2200°C in pure carbides with a wide range of C/U ratios (0.93 to 2.00) and in material doped with up to 2.4 wt% W, V, or Ta. Grain‐boundary diffusion is ∼ 103 to 105 times faster than volume diffusion, and, for UC1,0, has an activation enthalpy of 75.9 ± 9.1 kcal/mol, ∼ 55% of that for volume diffusion. In the monocarbide region, grain‐boundary mobility increases as the C/U ratio decreases and is impeded by the addition of impurities.
Equilibrium Studies of Fe in Alkali Phosphate Glasses
Authors: MAJUMDAR RABINDRANATH , LAHIRI DURGADAS
Published: October 2006

The Fe2+‐Fe3+ equilibrium in binary Na2O‐P2O5, glasses was studied by equilibrating glass melts at different temperatures in air. The enthalpy change (δH) of the reaction 1/2Fe2O3⇌FeO+1/4O2 was calculated for 4 glasses. The results indicate that (1) the equilibrium shifts toward the oxidized state as the Na2O content of the glass increases (plots of log ([Fe2+]/[Fe3+]) vs mol% alkali were linear) and (2) ΔH values for glasses of different composition are nearly equal but differ from the standard (calculated) value for the reaction. The experimental ΔH values were nearly equal to that for the reaction FePO4→1/3 Fe3(PO4)2+ 1/6P2O5+1/4O2, indicating that Fe forms phosphate or polyphosphate configurations in the Na2O‐P2O5 glasses. In certain of the glasses studied a faint‐pink solid precipitated; its X‐ray diffraction pattern indicated that its principal component is crystalline Na2Fe111P3O10.
Primary Recrystallization During the Hot‐Pressing of MgAl2O4
Authors: DAW JEFFREY D. , NICHOLSON PATRICK S.
Published: October 2006

Magnesium aluminate powders, both pure and doped with 0.5 wt% LiF, were hot‐pressed under vacuum at 1050°, 1170°, and 1290°C and 2500 and 5000 psi. Densification data were analyzed according to the classical hot‐pressing equation, In P/P0= ‐Kt; deviations are discussed in terms of the Occurrence of primary recrystallization. Examination of fracture surfaces and thermally etched polished surfaces by SEM corroborated this approach, indicating that strain‐induced primary recrystallization Occurred during hot‐pressing. Increased hydrostatic components of stress resulting from the presence of a liquid phase associated with LiF are proposed as the cause of plastic flow in the LiF‐doped spinel at low temperatures. Analogies are suggested between densification during primary recrystallization and reactive hot‐pressing.
Thermal Conductivity of Infrared Transparent Chalcogenide Glasses
Authors: HAYES D. J. , REA S. N. , HILTON A. R.
Published: October 2006

Chalcogenide glasses exhibit low thermal conductivities on the order of 10‐3 W cm‐1K‐1. Since many of these glasses are transparent in the infrared, the photon contribution to the apparent thermal conductivity of these materials can be significant even at relatively low temperatures, The temperature‐dependent thermal conductivity of Ge28 Sb12 Se60 was measured over the range 175 to 475 K and a simplified approach is presented to correct the data for radiation (photon) effects. In addition, room‐temperature thermal conductivities of 13 other glass compositions were measured. The phonon conductivities agreed well with simple Debye theory predictions after the radiation contributions were eliminated.
The System Hafnia‐Samaria
Authors: DURAN P.
Published: October 2006

The phase relations in the system HfO2‐Sm2O3 were studied by high‐temperature and room‐temperature X‐ray diffraction. The areas of existence of the solid solutions based on HfO2, Sm2Hf2O7, and Sm2O3 were determined using the lattice parameter method. Also, the influence of small additions of Sm2O3 on the monoclinic‐tetragonal transformation temperature of hafnia was studied. A tentative phase diagram is proposed.