bluuebunny/crossref_metadata_2025 huggingface dataset:
REACTIONS OF SLAG WITH REFRACTORIES II, REFRACTORY COATINGS PRODUCED WITH METALLIC ALUMINUM*
Authors: Schurecht H. G.
Published: October 2006

Abstract

Hard refractory coatings with good adherence were produced on fire brick by spraying a slip composed of clay and aluminum powder on the samples and firing. Similar coatings were produced by spraying molten aluminum on fire brick. The hardness probably is produced by heat developed from aluminothermic reactions between the aluminum and clay, and the strong adherence is caused by similar reactions between the aluminum and fireclay brick. These reactions were found to start between 750° to 930°C, and the heat generated may raise the temperature of the coating up to 1500°C in five minutes. The coatings increased the resistance of fireclay refractories to attack from basic slags but caused acid slags to corrode them more than where no coatings were employed.
THERMAL DISSOCIATION OF DIASPORE CLAY*
Authors: Herold Paul G. , Dodd C. M.
Published: October 2006

Abstract

Diaspora clay, under conditions of equilibrium, forms corundum and gamma alumina at 400°C. The gamma alumina gradually changes to corundum at higher temperatures, part of which combines with free silica to form mullite at about 1150°. Between 400° and 750°, there is a gradual increase in the size of the corundum unit cell as determined by X‐ray crystal analysis, which, upon continued heating at higher temperatures, gradually reduces to the true dimensions of corundum.
SUPPRESSION OF RADIATIONS AT HIGH TEMPERATURES BY MEANS OF CERAMIC COATINGS*
Authors: Bennett D. G.
Published: October 2006

Abstract

A method was developed for measuring the emissivities of ceramic coatings and ceramic‐coating materials with respect to oxidized stainless steel. The emissivities in the visible‐red and near‐infrared spectral regions were studied over a temperature range of 800° to 1600°F. The numerous materials investigated were found to cover an emissivity range from more than 100% to less than 10%. Lepidolite was the highest emitter, Uverite the lowest. Transmission of radiant energy decreased with coat thickness according to established laws. The transmission of radiant energy through coat‐bonding glasses could be greatly influenced by composition. Every material has a characteristic tendency to emit radiations at a given temperature. High‐temperature ceramic paints were found to be effective radiation suppressors and thermal insulators.
IMPROVEMENTS IN THE BUTTON TEST FOR DETERMINATION OF FRIT FLUIDITY*
Authors: MARBAKER Edward E.
Published: October 2006

Abstract

An investigation has been conducted on the factors involved in making the so‐called button test for frit fluidity in a small Hoskins electric furnace, in order to attain a high degree of reproducibility. Among the important factors are (1) the particle size and shape of the frit, (2) the kind and amount of binder, (3) the maintenance of constant dimensions and weight of the pellet, (4) the position of the test plate in the furnace, and (5) the time of heating in the horizontal position. An improved procedure is suggested for carrying out the test.
WATER CONTENT AND INFRARED TRANSMISSION OF SIMPLE GLASSES*
Authors: Harrison Anna J.
Published: October 2006

Abstract

Since glasses, which are high in silica or boric oxide content, have high absorption in the region of 2.7 to 3.0 microns, a study of the transmission characteristics of several simple glasses has been made.

Measurements of a variety of commercially available samples (5 mm. thick) of fused silica showed absorption in the 2.70‐micron band to vary from strong to essentially absent. Measurements of a number of samples (1 mm.) of fused boric oxide showed the 2.85 band to be variable and to be absent in some samples. The samples which did not show a minimum were prepared by bubbling the melt with boron trichloride to remove water and by casting between two pieces of platinum foil. The foil was removed in an anhydrous atmosphere at the time of measurement. Similar measurements on fused sodium tetraborate samples (1 mm.) showed the minimum at 2.95 microns to be variable but not completely removed. Bubbling was carried out with dry air in this case since boron trichloride reacts with sodium tetraborate.

The above bands are attributed to the OH vibrational absorption introduced by the water content of the glass. It is suggested that the exact position of the band might be an indication of the strength of bonding with the principal components of the glass.
QUANTITATIVE SPECTROGRAPHIC ANALYSIS OF POWDERED CERAMIC MATERIALS*
Authors: Zander J. M. , Terry J. H.
Published: October 2006

Abstract

A description is given of a rapid quantitative spectrographs method of analysis applicable to the quality control of milled minerals and powdered industrial chemicals. The method of sample preparation and complete spectrographic procedure is outlined for several specific materials. The effect of variable factors and the accuracy of the method is discussed.
EXAMINATION OF POLISHED SPECIMENS OF REFRACTORIES BY REFLECTED LIGHT*
Authors: Raymond Hensler J. , Zerfoss Samuel
Published: October 2006

Abstract

A discussion is presented of the preparation of the sample specimen and the polishing, etching, and identification of phases when the technique is applied to basic and silica refractories. This method shows the relationship of high‐iron slag to tridymite and cristobalite in the silica brick and it aids in the explanation of the bursting of chrome‐magnesite brick by iron oxide.
REACTIONS OCCURRING IN DECORATION OF VITRIFIED CHINAWARE USING UNDERGLAZE DECALCOMANIA METHOD*
Authors: Flannigan A. M.
Published: October 2006

Abstract

Studies were made on the causes of defects in underglaze decalcomania transfer on vitreous hotel chinaware. The best hardening‐on firing schedule to eliminate frizzling was as follows: (1) Heat as rapidly as ware will permit to 600°F., (2) at 600° to 800°F., heat at rate not exceeding 40° to 50°F. per hour, and (3) above 800 °F., heat as rapidly as ware will permit. The hardening‐on fire can be eliminated by reducing the coating of varnish through control of the viscosity of the varnish in the range of 4.0 to 6.0 (Mac‐Michael viscosimeter with No. 30 B & S wire, with cup rotating at 19 r.p.m.). The best results on the tackiness period were obtained in a room at 74 °F. dry bulb and 73% relative humidity.
SOME EXPERIMENTS ON CRYSTAL GROWTH AND SOLUTION IN GLASSES*
Authors: Swift Howard R.
Published: October 2006

Abstract

Experiments, which included the development of methods of measuring the linear rates of crystal growth and crystal solution and a study of surface crystallization, were conducted on commercial‐type glasses. A method of studying interdiffusion of two glasses of similar composition is described but no conclusions were reached.

It was found that (a) the rate of crystal growth is constant until the crystallization zones from the opposite surfaces meet and (b) the curve of crystal solution is continuous with that of crystal growth as the temperature is raised above the liquidus temperature. The results indicate that dust in the atmosphere is a major contributing factor promoting surface devitrification.
GLASS DENSITY DETERMINATIONS BY SINK‐FLOAT METHOD*
Authors: Duff R. D.
Published: October 2006

Abstract

Procedures are described which have been in use for several years in a bottle plant for the purpose of making daily determinations of glass density as a check on glass composition. These procedures are examined experimentally with a view to adopting any changes in technique, such as those suggested by Knight and others, which will yield results more quickly.

This study includes (1) a comparison of alternate methods of observing sink‐float temperatures as to precision and time required, (2) determination of the effect of handling and marking samples, (3) an estimate of the variability introduced into density results by the use of samples from commercially annealed bottles, (4) a comparison of the amount and type of information which may be expected from various plans of sampling plant production, and (5) data on the reliability for use in glass‐composition control of rod samples taken from forehearths, troughs, or tap streams.

The use of rod samples, prepared “as described” and without reannealing, is recommended in composition‐control work because (1) rod samples show less variability in the effect of thermal history on density than do those from lehr‐annealed bottles from a number of lehrs, (2) elapsed time between entry of batch into the furnace and the completion of density determinations on glass made therefrom is approximately three hours less than when lehr‐annealed bottle samples are used and approximately six hours less than when* reannealed samples from bottles are used, and (3) rod samples are available regardless of whether or not finished ware is being produced.
CONTROL OF COLOR ON AMBER CONTAINER WARE DURING PRODUCTION*
Authors: Manring W. H.
Published: October 2006

Abstract

A rapid method for determining the amber color of glasses has been developed by measuring light transmission at 5250 a.u. with a revised Fisher electrophotometer. The results are in fair agreement with data obtained by slower, more elaborate equipment. Control charts show that amber color becomes darker with increased tank pull. Major causes of color fluctuation are discussed.
CHARACTERISTICS OF ZIRCON PORCELAIN*
Authors: Russell Ralston , Mohr W. C.
Published: October 2006

Abstract

The manufacturing characteristics, properties, uses, and future possibilities of zircon porcelain are discussed. Any of the usua1 manufacturing processes may be used, but special glazes must be employed because zircon absorbs normal glazes: The typical properties (approximate values) are (a) linear expansion, 4.5 × 10‐6 per °C., (b) thermal conductivity, 0.012 (normal porcelain, 0.004), (c) tensile strength, 13,000 Ib. per sq. in., (d) compressive strength, 100,000 Ib. per sq. in., (e) modulus of elasticity, 25 × 106 Ib. per sq. in., (f) thermal‐shock resistance, good, (g) power factor at 1 mc., 0.001, and (h) dielectric constant, 9.
SUBSTITUTION OF DOMESTIC MINERALS FOR INDIA KYANITE: VI, REFRACTORY PROPERTIES OF GEORGIA MASSIVE KYANITE*
Authors: McVay T. N. , Wilson Hewitt
Published: October 2006

Abstract

The massive kyanite of Georgia is similar in structure to India kyanite, but it contains quartz with only occasional small amounts of corundum; sericite between the kyanite crystals is common. Excellent coarse grog (67% through 6‐ on 35‐mesh) can be produced from this kyanite. Maximum expansion of the rock during calcining occurs at 1400°C. with slight shrinkage thereafter.

Brick were made of the kyanite grog with 3% and 10%, respectively, of EPK (Florida) clay; both had excellent resistance to load at elevated temperatures and met the reheat specifications of the Navy Department and the A.S.T.M. In the panel spalling test, Georgia kyanite brick showed approximately 20% loss, whereas India kyanite brick of the same grain size and clay content showed only 0.3% loss. Intensive prospecting is necessary and the unusual mining and cleaning operations with present known deposits make large‐scale commercial operation questionable.
X‐RAY DIFFRACTION DATA FOR COMPOUNDS IN SYSTEMS Li2O‐SiO2 AND BaO‐SiO2*
Authors: Austin Alfred E.
Published: October 2006

Abstract

X‐ray diffraction powder patterns for 2Li2O·SiO2, Li2O·SiO2, Li2O·2SiO2, 2BaO·SiO2, BaO·SiO2,2BaO·3SiO2, BaO·2SiO2, and K2O·4PbO·8SiO2 are presented.
TESTS FOR HOT‐WATER RESISTANCE OF TANK ENAMELS*
Authors: Moore Dwight G. , Harrison William N.
Published: October 2006

Abstract

The resistance to attack by hot water of a representative group of commercial enamels, designed especially for use on hot‐water tanks, and of several nontank enamels was measured by the following three types of test: (A) loss of gloss after periods up to several hours in a conventional autoclave with distilled water, (B) loss of gloss after one day to two weeks in apparatus which kept the specimens in contact with constantly changing, boiling distilled water, and (C) loss in thickness after periods up to 5000 hours (208 days) in a modified autoclave with circulating aerated tap water under pressure. The tests are described in detail, comparisons are made, and the loss‐of‐gloss test with boiling distilled water as used in Commercial Standard CS115–44 is discussed.
FACTORS AFFECTING ORANGE PEEL*
Authors: Steencken John J.
Published: October 2006

Abstract

The effects of spraying techniques on orange‐peel surface of porcelain enamel were studied. The volume of atomizing air per unit volume of atomized slip is the predominating factor, and the ratio appears to be 1000 to 1200 cc. of air per 1.0 cc. of slip for average conditions. The angle of incidence should be 60 degrees or more. The minimum fluid and atomizing pressures should be adjusted to suit the specific gun nozzle and tip but should maintain the air‐to‐slip ratio indicated. The following conclusions are given: (1) The type of fluid nozzle of the spray gun alone does not appreciably affect orange peel; (2) the type of air cap and its air capacity affects orange peel definitely; the tip with the largest number of orifices and greatest air capacity offers much better atomization and smoother spray, and there is a definite indication that the fineness and degree of atomization is a measure of the amount of orange peel that may be expected; (3) lowering the atomizing pressure increases the tendency toward orange peel; (4) increasing the rate of flow of the enamel through the spray gun increases the tendency toward orange peel; (5) closer spraying distances increase the tendency toward orange peel; (6) decreasing the angle of incidence of the spray increases the tendency toward orange peel; (7) a round, concentrated spray has a greater tendency toward orange peel than the wide flat spray fan; (8) increasing the application weight increases the tendency toward orange peel although good results could be obtained up to 50 to 55 gm. per sq. ft. in one coat; (9) decreasing the specific gravity of the enamel slip increases the tendency toward orange peel; the best specific gravities for spraying cover‐coat enamels are above 1.80; and (10) the viscosity of the enamel slip does not appreciably affect the orange‐peel tendencies of the enamel, but there is a definite indication that the best results are obtained with the higher viscosities.
FUNDAMENTAL CONDITION OF GLASS FORMATION*
Authors: Sun Kuan‐Han
Published: October 2006

Abstract

The fundamental condition for glass formation is the existence of strongly bonded large networks or long chains of atoms in the liquid. Such chains or networks prevent or hinder the orderly orientation of atoms in the chains or networks themselves and also that of atoms, not in the networks in the liquid, near the melting point or liquidus temperature. A liquid structure will persist when the liquid is cooled below the melting point or liquidus temperature and will continue until free, long‐range movement of atoms becomes impossible. In order to obtain such long chains or large networks, it is necessary that (1) the bond strength of atoms in the chains or networks be very strong; (2) the small ring formation of these strongly bonded atoms be at a minimum; and (3) the relative numbers of various atoms in the chains or networks be such that at least a continuous chain is configuratively and structurally possible; at the same time, the coordination numbers of the glassforming atoms should be as small as possible to keep the bond strong. The general treatment is applied to all kinds of glasses, particularly oxide glasses. The bond strengths of all M—O single‐bond linkages in these glasses are calculated and tabulated here for the first time. The bond strength of all the glassformers was found to be greater than 80 kilocalories per Avogadro bond, that of the intermediates between 60 and 80, and that of the modifiers below 60; the transition is continuous, and the division into glassformers, intermediates, and modifiers is arbitrary.
CALCULATION OF REFRACTIVE INDEX OF A GLASS AS A DIRECT FUNCTION OF ITS COMPOSITION*
Authors: Sun Kuan‐Han
Published: October 2006

Abstract

Methods have been presented for the direct calculation of refractive index of a glass from its composition. For a given region of composition and structure of silicate glasses, defined by the ratio of Si to the total number of oxygen, or NSi, the excess refractive index (n— 1) is found to be linearly additive of composition. Equations and constants are given for various expressions of composition, including the weight percentages. Part of the constants have physical significance since they represent the refractive‐index contribution of the components concerned.
CONTRIBUTION TO REFRACTIVE INDEX AND ABBE VALUE OF OXIDE COMPONENTS IN GLASS*
Authors: Sun Kuan‐Han
Published: October 2006

Abstract

A plot is given showing the relationship between the refractive index, n, and the Abbe value, v, for many oxide components forming constituents of a glass, particularly of the silicate type. The n and v values were derived previously by various authors. A comparison is also given of the refractive indices of borate, silicate, germanate, and phosphate glasses.
SEMICONDUCTING CERAMIC MATERIALS*
Authors: Hausner Henry H.
Published: October 2006

Abstract

The paper presents a brief résumé on the principles of electrical conductivity. Studies were made on compositions consisting mainly of oxides such as TiO2, Fe2O3, FesO4, ZrO2, and others. The effects of composition on the electrical resistivity and its temperature coefficient of these semiconductors were investigated. The reduction of the oxides and its effect on electrical properties are described. Test results are correlated with the theory. The effect of activation energy on electrical properties of the semiconductors is also described.
AN INTERMEDIATE COMPOUND IN THE SYSTEM BeO ‐Al2O3 (CHRYSOBERYL)‐Al2O3 (CORUNDUM)*
Authors: Foster Wilfrid R. , Royal Herbert F.
Published: October 2006

Abstract

The results of studies in the high‐alumina portion of the system BeO‐ Al2O3 do not agree with those of previous workers. An X‐ray study of sintered and fused mixtures in this portion of the system indicates the existence of a hitherto unrecognized compound intermediate between chrysoberyl (BeO‐ Al2O3) and corundum (Al2O3) and possessing the probable formula BeO‐3 Al2O3. The new compound is optically almost identical with chrysoberyl but gives a decidedly different X‐ray pattern. Discussion and criticism of earlier work are presented with the aid of equilibrium diagrams.
EXPLOSION TESTS ON GLASS WINDOWS, EFFECT ON GLASS BREAKAGE OF VARYING THE RATE OF PRESSURE APPLICATION*
Authors: Thompson Norman J. , Cousins Edward W.
Published: October 2006

Abstract

Tests were made to determine whether or not glass windows would be of value in preventing building damage from internal explosions involving combustible dusts or vapors It was found that the effective strength of glass panes increases in an approximate linear ratio with increased rate of pressure application. It was concluded that window glass is of dubious value for explosion venting purposes, except possibly for explosions of high pressure but of very short duration, such as those that might occur if small quantities of high explosive were placed relatively near the windows.
INDUCTION FURNACE FOR HIGH‐TEMPERATURE CERAMIC RESEARCH*
Authors: Johnson P. D.
Published: October 2006

Abstract

A vacuum induction furnace for high‐temperature research is described. With the use of molybdenum units, temperatures up to 2300°C. may be obtained.
CERAMIC SPARK‐PLUG INSULATORS*
Authors: Riddle Frank H.
Published: October 2006

Foreword

It was with a feeling of deep humility that I received the invitation to be the Edward Orton, Jr., Fellow Lecturer this year. Every year, when the program of the Annual Meeting is announced in The Bulletin, my first interest in it is the Orton Lecture, and the significant honor bestowed upon the man chosen to give it.

The availability of the literature of The American Ceramic Society to me when I was graduated from high school and began to work in an art pottery helped me to decide to go to college and to choose the course in ceramics at Ohio State University. In doing so, I was very fortunate in having been closely associated with Doctor Orton both as a student and as an instructor. We became friends, and this friendship continued through the years. I am very grateful to have this opportunity to acknowledge the assistance and counsel of Edward Orton, Jr., and his associates.
INFLUENCE OF MINOR ADDITIONS ON COLOR AND ELECTRICAL PROPERTIES OF RUTILE*
Authors: Johnson Gordon , Weyl W. A.
Published: October 2006

Abstract

In connection with some work on the color of minerals it was found that the presence of Ti3+ in rutile can originate from two basically different causes.

The bluish color of certain rutile preparations due to the presence of the Ti3+ ion of Ti2O3 is the result of (a) reducing conditions causing an oxygen deficiency in the rutile lattice or (b) the presence of cations having a valency higher than four. Replacing a tetravalent titanium ion by a pentavalent ion, for example, Sb5+, forces another titanium ion into the trivalent state in order to maintain the electroneutrality of the lattice The presence of ZrO2 in TiO2 makes the rutile more susceptible to certain impurities in its lattice, thus enhancing discoloration. The value of these crystal‐chemical considerations for the opacification of enamels and the dielectric properties of ceramic bodies containing rutile or rutile‐zirconia mixed crystals is pointed out.
CORRELATION OF GLAZE‐BODY STRESSES WITH THERMAL PROPERTIES OF WHITEWARE BODIES*
Authors: Cook Ralph L. , Brunner Cedric D.
Published: October 2006

Abstract

Several lead borosilicate glazes with high to low thermal expansion were applied to a bisque whiteware body having porosities ranging from 20 to 30%, and the thermal properties were studied. Test pieces were subjected to an autoclave test at 50, 150, and 300 lb. per sq. in. and to a thermal‐shock test by quenching from 400° to 600°F. into cold water. The thermal‐expansion curves for the various glazes and for the body at each porosity were determined on the interferometer. The glaze‐fit ring test was used to determine the degree of tensile and compressive stress, and these stresses were plotted graphically with the body porosity. The resistance to crazing was increased in both the autoclave and thermal‐shock tests as the thermal expansion of the glazes, as measured on the interferometer, decreased. The 10% porosity body gave the best results in the thermal‐shock test. A close correlation was found between the thermal‐expansion curves for the glazes and bodies of varying porosity and the stress characteristics shown by the glaze‐fit ring test.
EFFECT OF REFRACTORY MILL ADDITIONS ON MOLTEN APPARENT VISCOSITIES OF STEEL GROUND‐COAT ENAMELS*
Authors: Bruce B. D. , Sharon A. V.
Published: October 2006

Abstract

A viscosimeter of the rotating‐cylinder type was used to determine the effect of refractory mill additions on the molten apparent viscosity of steel ground‐coat enamel. A blend of three commercial frits was used as the base enamel to study the effect on molten viscosity of various amounts of silica, feldspar; and nepheline syenite.

Results indicated that silica imparted the greatest increase in molten viscosity. Additions of feldspar and nepheline syenite of 9% or less increased the molten viscosity about the Same amount. With, however, a 12% addition of refractory, feldspar was more effective for increasing molten viscosity than nepheline syenite.
PROPERTIES AND USES OF PURE OXIDE HEAVY REFRACTORIES*
Authors: Whittemore O. J.
Published: October 2006

Abstract

Thermal conductivity, high‐temperature load‐bearing resistance, reheat shrinkage, and porosity were determined on new pure oxide heavy refractories of alumina, magnesia, and stabilized zirconia. Alumina refractories were shown to be capable of lining furnaces for operation to 1900 °C, and magnesia and stabilized zirconia refractories to at least 2300 °C. The thermal conductivity of alumina refractories was found to vary directly with density, and four mixtures are described with conductivities ranging from 6 to 18 B.t.u. per hr. per sq. ft. per in. per °F. at 1800°F. Stabilized zirconia refractories, although having twice the bulk density of fire‐clay brick, showed lower thermal conductivity. The uses and limitations of pure oxide heavy refractories are discussed.
DEVELOPMENT OF CORDIERITE BODIES WITH SIERRALITE, A NEW CERAMIC MATERIAL*
Authors: Lamar R. S.
Published: October 2006

Abstract

Several cordierite ceramic bodies exhibiting exceptionally low coefficients of thermal expansion and good thermal‐shock resistance have been developed. Firing ranges, coefficients of thermal expansion, and results of petrographic examinations are given for each body.

Bodies prepared from sierralite, a hydrous magnesium aluminum silicate, and clay had exceptionally low coefficients of thermal expansion but short firing ranges. The addition of from 5 to 20% zircon extended the firing range greatly without materially affecting the thermal expansion or thermal‐shock resistance.
FUNDAMENTAL STUDY, AND EQUIPMENT FOR SINTERING AND TESTING OF CERMET BODIES, I–III*
Authors: Blackburn A. R. , Shevlin T. S. , Lowers H. R.
Published: October 2006

Abstract

Cermet bodies, † composed of metals and oxides, are being developed for high‐temperature service. Part I covers the theoretical aspects of experiments of a fundamental chemistry nature which accompanied the laboratory development of test specimens. Compacts of metal powders (Xi, Fe, Co, Cr, and Cr‐B) were fired at 2880° to 3500°F. on pure Al2O3 tile in various controlled atmospheres. The results indicate that a controlled layer of oxide on the surfaces of the metal‐powder grains is essential for good bonding. Special furnaces, described in Part II, were necessary for the fundamental study and for sintering cermet specimens. Equipment for determining instantaneous modulus of rupture and tensile rupture, and longtime stress‐rupture in bending at temperatures up to 2400°F., is described in Part III.
DENSE CORDIERITE BODIES*
Authors: Gebler Kenneth A. , Wisely Harriet R.
Published: October 2006

Cordierite bodies having virtually zero porosity when fired between 1285° and 1325°C. were obtained by using calcined blends of MgCO3, talc, and clay; the calcine was combined with raw clay to form the body. These bodies were characterized by low thermal expansion, good mechanical strength, and excellent thermal‐shock resistance.
A GLASS SAND BENEFICIATION PROCESS*
Authors: Poole James P.
Published: October 2006

Abstract

A technique of attrition grinding is described that makes possible the production of a high‐quality sand for fit glass from a low‐grade sandstone. Details of a proposed plant with a daily capacity of 300 tons of sand are given.
COLORATION OF GLASS BY GOLD, SILVER, AND COPPER*
Authors: Stookey S. D.
Published: October 2006

Abstract

A discussion of hypotheses concerning the development of gold ruby, silver yellow, and copper ruby colors in silicate glass is presented. Experiments are described which were designed to determine whether gold dissolves in molten silicate glasses in an oxidized (ionic) state or as uncombined metal. Results are believed to prove that gold dissolves as ions rather than in the metallic state. Similar conclusions apply to silver and copper. The metal coloration results from reduction of the metal ions to insoluble metal at low temperatures, the reducing agent being Sn+2, or other polyvalent ions, as postulated by Badger, Weyl, and Rudow and by Dietzel.
METHOD OF DETERMINING THE DIELECTRIC CONSTANT AND POWER FACTOR OF CERAMICS AT 100 MEGACYCLES AS A FUNCTION OF TEMPERATURE*
Authors: Evans Howard J.
Published: October 2006

Abstract

Many applications of ceramic insulators used in electron tubes subject the ceramic to temperatures of several hundred degrees centigrade and to high‐frequency electric fields. At the higher radio frequencies the dielectric heating in the insulator often becomes great enough to cause the insulator to fail.

This paper describes a method of measuring the dielectric constant and power factor versus temperature for glasses and ceramics at 100 mc. per second. Measurements are given for certain ceramics at temperatures up to 500 °C. and are compared with measurements made at 15 mc. per second.
Electrode Effects in the Measurement of Ionic Conductivity
Authors: FRANKLIN A. D.
Published: October 2006

Even with thermodynamically reversible electrodes, slow processes inhibiting the discharge of ions at the interface between a solid ionic conductor and the electrode can give rise to overvoltages when current is passed or to an interface impedance in ac measurements. Some of the more important of the mechanisms responsible for this inhibition, i.e. boundary layers, slow charge‐transfer processes with double‐layer formation, product storage in the electrodes with slow mass transport to the ultimate thermodynamic reservoirs, and rough or porous surfaces, can be understood in a nonrigorous physical way with the help of simple models. The properties of such systems can often be expressed in terms of equivalent circuits, and these are then very useful in analyzing the behavior of specific systems. Examples from studies of materials such as CaO‐stabilized ZrO2 (oxygen‐ion conductor) and β‐Al2O3 (sodium‐ion conductor) illustrate these effects.
Electrical Resistivity of Hot‐Pressed Compacts
Authors: RAMANAN T. , CHAKLADER A. C. D.
Published: October 2006

The electrical resistivity of compacts of glass and nickel spheres has been correlated with bulk density during hot‐pressing. Conductivity, based on deformation of spheres into several geometric shapes under hot‐pressing conditions, is described by σm/σc=α (D2/3β2/3R2— 1), where σm and σc are the conductivities of a compact of spheres at relative density D and theoretical density (D= 1), respectively; α and β are constants depending on geometry; and R is the radius of the deformed sphere.
Reproducibilities of Some Physical Properties of MgF2
Authors: Bailey D. M. , Calderwood F. W. , Greiner J. D. , Hunter O. , Smith J. F. , Schiltz R. J.
Published: October 2006

Opticalquality MgF, specimens selected to represent varying levels of fabrication stresses and impurities were examined to determine their elastic moduli, thermal expansions, and thermal conductivities. These properties proved to be insensitive to the variations in impurities among the samples. The elastic moduli were also insensitive to the variations in residual strain. Any sensitivity to residual strain was masked, in the case of thermal conductivity measurements, by the fracture of highly strained specimens during sample manipulation and, in the case of thermal expansion measurements, by crushing the specimens to powder before measurement.
Effect of Impurities on the High‐Temperature Creep of LiF
Authors: RUOFF ARTHUR L. , NARAYAN RAO C. V. S.
Published: October 2006

Creep of undoped and Mg‐doped single‐crystal LiF was investigated in the range 650° to 750°C. The behavior observed is similar to that of pure metals. The strain rate was proportional to (stress)″, with n= 5.0±0.4 at T= 650° and 700°C and n= 3.60±0.2 at T= 750°C; n was independent of dopant level. The activation energies for creep were 2.09±0.08 eV for undoped specimens in the intrinsic range and 2.60±0.08 eV for doped specimens in the extrinsic range. A lower creep rate was found in doped samples than in undoped samples. However, the creep strain rates observed in heavily doped samples were not inversely proportional to the dopant level. The observations for pure LiF are explained on the basis of vacancy diffusion through the lattice. A model based on dopant cation vacancy complexes and binding of dopant to charged dislocations is presented to explain the behavior of the doped specimens.
Topology of Liquidus Phase Diagrams of Charge‐Asymmetric Reciprocal Molten Salt Systems
Authors: SABOUNGI MARIE‐LOUISE , BLANDER MILTON
Published: October 2006

An empirical extension of conformal ionic solution theory is presented which describes the solution behavior of a class of reciprocal molten salt systems, the A+qA, B+qB∥C‐qC, D‐qD charge‐asymmetric systems. The thermodynamic properties of such ternary systems can be calculated from data on the standard free energy change for the metathetical reaction between the 4 pure constituents and solution data on the 4 binary subsystems. Calculated liquidus phase diagrams for the systems Na,Sr∥Cl,NO3; Na,Ba∥Cl,NO3; Li,K∥Cl,CrO4; Li,K∥Br,CrO4; and Na,Ca∥F,Cl agree well with measurements within experimental uncertainties. These systems are illustrative of a wide range of values of the thermodynamic quantities used in the calculations. The equations developed should prove useful as a test of the self‐consistency of reported phase diagrams, as a means of calculating Liquidus temperatures in experimentally inaccessible regions, and as an aid in constructing phase diagrams from a minimum number of measurements.
Solubility Limit of La in the Lead Zirconate‐Titanate System
Authors: SCHULZE W. A. , MILLER T. G. , BIGGERS J. V.
Published: October 2006

The disappearing‐phase method was used to determine the extent of the solid‐solution region of the PLZT system for conventionally sintered ceramics prepared at 1100° and 1300°C in a PbO atmosphere provided by pbZrO3. A decrease in the firing temperature from 1300° to 1100°C lowers the solubility limit by 5 to 8 at.% La. Beyond the limits of solubility, additional La forms La2Zr2O7 and/or La2Ti2O7. The limit determined by the disappearing‐phase method (1300°C firing) is compared to values determined by the parametric method. The Curie temperature is stabilized at 5 at.% La for modified PbZrO3 (1300°C firing).
Bending of Elastically Supported Axisymmetric Plates
Authors: GULATI S. T.
Published: October 2006

In the bending of symmetrically loaded circular plates of brittle material, e.g. glass, which are supported between flexible gaskets at the periphery, large errors can result in estimating the stresses and deflections in the plate if it is assumed that the plate is simply supported. This paper uses the exact numerical solution, given elsewhere, in comparing the exact stresses and deflections with those obtained by assuming simply supported edges. It is shown that gasket width and stiffness are important in controlling the maximum stress. The deviation from an assumption of simple support is greatest when the plate is thin.
Crystal Chemistry and Reactivity of the MgO‐Stabilized Alites
Authors: THOMPSON R. A. , KILLOH D. C. , FORRESTER J. A.
Published: October 2006

The reactivity with water of 3CaO· SiO2 stabilized in the tri‐clinic and monoclinic forms with MgO was studied by monitoring the heat of hydration using conduction calorimetry. The early heats of hydration increase moderately when the MgO content brings the sample near the monoclinic‐triclinic transition point. Reactivity increases markedly when samples with high MgO contents are annealed. Annealing appears to cause separation of some of the MgO and also eventually converts monoclinic samples to the triclinic form. Samples containing < 0.9% MgO showed a slight reduction in reactivity after they were annealed, but pure 3CaO· SiO2 was unaffected. Preparation of the samples and their examination by X‐ray diffraction and chemical extraction methods are described. Possible explanations for the hydration behavior are discussed.
Hydration and Strength Development in Tricalcium Silicate Pastes Seeded with Afwillite
Authors: DAVIS R. W. , YOUNG J. F.
Published: October 2006

The formation of afwillite in tricalcium silicate pastes initiated by ding with crystals was studied to determine the effects on development of tensile strength. Afwillite forms in pastes only when fresh surfaces of both tricalcium silicate and afwillite seed are exposed by initial grinding. Higher early strengths reflect increased rates of hydration in seeded pastes, but strengths at later ages are lower than those of untreated pastes. At all ages tensile strength is lower at a given degree of hydration in seeded pastes than in unseeded ones; this behavior is considered to result from changes in pore‐size distribution which occur as afwillite forms. Afwillite initially forms concomitantly with calcium silicate hydrate gel but later arises from conversion of the gel.
Strength and Microstructure in Lithium Disilicate Glass‐Ceramics
Authors: BOROM MARCUS P. , TURKALO ANNA M. , DOREMUS ROBERT H.
Published: October 2006

The effect of heat treatment on the microstructure of Li2O‐Al2O3·SiO2 glass‐ceramics which contain crystals of either Li2SiO3, Li2Si2O5, or both was investigated quantitatively. Strength determinations for abraded rods were correlated with heat treatment on the basis of both size and distribution of crystals and the type and amount of crystal phases present. The presence of Li2Si2O5 crystals enhanced the strength, whereas the presence of Li2SiO3 crystals did not change the strength of the abraded parent glass. The interrelation between strength and microstructure is discussed.
Ceramic Models for Study of Piezoelectricity in Solids
Authors: WILLIAMS WENDELL S. , BREGER LANCE , JOHNSON MARVIN
Published: October 2006

The piezoelectric behavior of certain biological materials (bone and tendon) was studied by comparing them with well‐understood piezoelectric ceramics (quartz and tourmaline). The results show that, whereas the ceramic model materials conform to the standard theory of piezoelectricity in both compression and bending, the organic materials deviate quantitatively and qualitatively in bending. An extension of the formal theory is developed to include a polarization proportional to the gradient of the stress and yields predictions in accord with the experimental findings for bone and tendon. Implications for transducers competing with electrical ceramics are noted.
Strength Degradation of Brittle Surfaces: Blunt Indenters
Authors: LAWN B. R. , WIEDERHORN S. M. , JOHNSON H. H.
Published: October 2006

Indentation fracture mechanics is used to develop a theoretical basis for predetermining the strength properties of brittle surfaces in prospective contact situations. Indenters are classified as blunt or sharp; only the first is considered in the present work. The classical Hertzian cone crack conveniently models the fracture damage incurred by the surface in this class of indentation event. Significant degradation is predicted at a critical contact load; when the load is increased beyond this critical level, further degradation occurs at a relatively slight rate. Bend tests on abraded glass slabs confirm the essential features of the theoretical predictions. The controlling variables in the degradation process, notably starting flaw size and in‐denter radius, are investigated systematically. An indication is also given as to optimization of material parameters.
Predictability Gap Between Science and Technology of Cements: I, Characterization of Hydraulic Cements
Authors: SEREDA P. J. , RAMACHANDRAN V. S.
Published: October 2006

Scientific publications fall, traditionally, into two general categories: reports of original research and state‐of‐the‐art reviews of areas of research. In both types, scientists communicate with other scientists. If science is to Serve technology, however, there must be effective communication or transfer of information between the scientist and the technologist. At present, many believe that such transfer is not very effective and that this ineffectiveness contributes to the difficulty the technologist experiences in predicting the performance of materials. The authors plan a series of papers that will provide a critical assessment of what will be required if research is to improve predictability in the technology of cements. Part I discusses problems involved in the characterization of hydraulic cements in terms of reactivity, role of admixtures, surface area, crystal modification, and chemical composition.
Measurements of High‐Temperature Absorption Coefficients of Glasses
Authors: WEDDING BRENT
Published: October 2006

An instrument for measuring spectral transmittance at wavelengths from 0.25 to 7 μm of samples at temperatures between ambient and 1300°C is described. Data showing the effect of temperature on the fundamental, Fe, and water absorption bands in glass are given and discussed.
Influence of Strain Energy on Kinetics of Ion Exchange in Glass
Authors: VARSHNEYA A. K.
Published: October 2006

The kinetics of the K+⇌ Na+ exchange in Na2O·3SiO2 glass at 350°C were studied. The distribution of K in the glass specimens after exchange in molten KNO3 was determined with an electron microprobe. The calculated interdiffusion coefficients, which varied with the local composition in the glass, were compared with those obtained using the Nernst‐Planck equation and Fleming and Day's self‐diffusion data for xNa2O. (1‐x)K2O·3SiO2 glasses. Deviations of the observed interdiffusion coefficient from the Nernst‐Planck formula were noted. These deviations are explained on the basis of changes in the average size of the alkali ion sites and in the strain energy that occur during ion exchange.
Rare‐Earth‐Oxide‐Metal Eutectic Composites
Authors: STENDERA J. W. , BENZEL J. F.
Published: October 2006

Unidirectionally solidified composites of a rare‐earth sesquioxide + CeO2+ (Mo or W) and of CeO2+ (Mo or W) were grown using the direct‐rf‐coupling internal‐molten‐zone technique. The dramatic fiber improvement on addition of CeO2 to the sesquioxide systems suggests that it provides extra loosely bound oxygen to increase the solubility of the metal in the molten oxide. The composites have extensive areas of ordered eutectic growth containing from 8 to 50 × 106 metal fibers/cm2; the fibers are 0.1 to 0.6 μm in diameter. Fiber density increased almost linearly as the growth rate was increased from 0.5 to × 5.0 cm/h. Slow growth favors the platelet metal morphology over the fiber morphology. Platelets are typically observed in areas where high impurity concentrations would be expected, e.g. at the top of the solidified zone and at grain boundaries.
Application of Finite Element Analysis to Ceramic Components
Authors: VISSER C. , LIEN S. , SCHALLER R. J.
Published: October 2006

A finite element analysis of a rotating ceramic gas turbine blade consisting of an airfoil and root is discussed. Three‐dimensional results were obtained for the blade using both isotropic and orthotropic material properties. A two‐dimensional study of the root considered the effects of friction, contact area, and root geometry.
Creep Behavior of Uranium Carbide‐Based Alloys
Authors: SELTZER M. S. , WRIGHT T. R. , MOAK D. P.
Published: October 2006

Compression creep tests were performed on fully dense specimens of UC1.01, UC1.05, UC1.01.+ 4 wt% W, and U0.9Zr0.1C1.01+ 4 wt% W. Steady‐state creep rates were measured from 1400° to 1800°C in a vacuum of 1.33 × 10‐3 N/m2 (1 × 10‐5 torr) at stresses of 4.55 to 69.0 MN/m2 (660 to 10,000 psi). The data for UC1.01 could best be fit by an expression of the form ɛ= 1773σ6.024 exp (106.5/RT), where σ is the steady‐state creep rate (h‐l), σ is the applied stress (MN/m2), and the creep activation energy is given in kcal/mol. The stress dependence for creep of UC1.05 decreased with decreasing temperature because of second‐phase precipitation; therefore, a unique creep activation energy could not be established for this U/C ratio. At all temperatures, the creep strength of UC1.05 exceeded that of UC1.01. For example, at 1700 ° C steady‐state creep rates for UC1.05 are ∼1/4 those for UC1.01, but at 1400°C the creep rates are ∼ 3 orders of magnitude less. At 1700°C, creep rates for UC alloys are ∼4 orders of magnitude lower than those for unalloyed UC1.01.
Microstructures and Crystallization Behavior of Gels in the System La2O3‐SiO2,
Authors: MUKHERJEE S. P. , ZARZYCKI J.
Published: October 2006

Gels in the system La2O3,‐SiO2, were prepared by two methods, one based on the gelling of a commercial silica hydrosol and one based on the polymerization reaction of alkoxysilane. The microstructural changes and the variability in crystallization rates of the gels in relation to the methods of preparation, thermal treatment, and composition were investigated.
The Role of Cerium Orthosilicate in the Densification of Si3N4
Authors: MAH TAI‐IL , MAZDIYASNI K. S. , RUH ROBERT
Published: October 2006

The existence of compounds between Si3N4‐CeO2 and Si3N4‐Ce2O3 was investigated for firing temperatures of 1600° to 1700°C. The two new monoclinic compounds found were Ce2O3·2Si3N4 with lattice parameters a= 16.288, b= 4.848, and c=7.853 Å and β=91.54° and Ce4Si2O7N2 with lattice parameters a= 10.360, b= 10.865, and c=3.974 Å and β=90.33°. Cerium orthosilicate (Ce4.67(SiO4)3O) is present during firing as a glassy intermediate phase which promotes sintering and densification and then reacts with silicon nitride to form cerium silicon oxynitrde (CeSiO2N).
Thermal, Structural, and Dielectric Properties of Cu‐Doped Ge‐S Glasses
Authors: DOUPOVEC JURAJ , THURZO ILJA , VLASÁK GABRIEL
Published: October 2006

Glasses of GeS1.5+y at.% Cu and GeS1.375+z at.% Cu were analyzed by DTA. For concentrations y≊2.5 and z≊4, new exothermic transformations and an initial small endothermic effect appear. All these transformations occur below the glass transition temperature of the original Ge:S glass, Analysis by X‐ray and electron diffraction showed that this devitrification process is connected with crystallization of a Cu2GeS3 phase. Electron transmission microscopy showed that this crystalline phase is dispersed in a glassy matrix as disconnected aggregates with irregular symmetry. Near the maximum copper concentration y≊5, z≊6) at the boundary of the glass‐forming region, there is one additional exothermic transformation in the system GeS1.5+y at.% Cu and two in the system GeS1.375+z at.% Cu, one of them corresponding to crystallization of the Cu3GeS4 phase. X‐ray diffraction patterns of the crystalline phases are shown. The spectrum of ionic thermocurrents in such glassyceramic material shows a new peak at 120 K which is probably related to interfacial polarization associated with the crystalline phase‐glassy matrix boundary.
Kinetics of Formation of an Iron‐Zircon Pink Color
Authors: EPPLER RICHARD A.
Published: October 2006

The kinetics of formation of an iron‐zircon pink color were studied by X‐ray diffraction. The iron reacts with the zirconia at a temperature below the reaction temperature. The initial reaction is nucleation‐growth‐controlled. At higher percent conversion a change in mechanism occurs, probably becoming diffusion‐controlled. At any given reaction temperature, there is an apparent limiting percent conversion.
Effect of MoO3 Addition on the Grain Growth Kinetics of a Manganese Zinc Ferrite
Authors: JAIN G. C. , DAS B. K. , GOEL N. C.
Published: October 2006

The effect of MoO3 addition on the grain growth and densification kinetics of a high permeability manganese zinc ferrite was studied. Grain growth in the presence of a small amount of MoO3 occurs in two main stages characterized by a faster rate of grain growth accompanied by rapid densification and pore coalescence in the first stage, when the MoO3 is present as a liquid phase along the grain boundaries, and comparatively slower rates of grain growth and densification than those for the basic composition in the second stage, when MoO3 evaporates from the matrix. The activation energies for grain growth in these stages suggested that surface and volume diffusion mechanisms were operating in the first and second stages respectively.