bluuebunny/crossref_metadata_2025 huggingface dataset:
Sintering of High‐Purity Magnesia
Authors: ALLISON A. G. , SESLER E. C. , HALDY N. L. , DUCKWORTH W. H.
Published: June 2006

The effect of calcining temperatures on the sinter ability of high‐purity magnesia powders was investigated. A marked decrease in the density of sintered (fired) compacts occurred when petro‐graphically identifiable periclase was formed in calcining. By employing proper heat‐treatment in calcining the powder, ceramic bodies with zero apparent porosities were obtained at sintering temperatures as low as 1650°C. It is suggested that proper calcinations might also facilitate the preparation of dense ceramics of other oxides.
Antimonates as Additives to Barium Titanate Dielectric Bodies
Authors: COFFEEN WILLIAM W.
Published: June 2006

Antimonates of a number of the alkalis and alkaline earths and of several other metals were prepared and their ceramic and dielectric properties were determined. Only porous bodies could be produced from the individual anti‐monates. Dielectric measurements on these bodies showed that they all had relatively low dielectric constants. The properties of dielectric bodies in the binary systems composed of the an‐timonates of sodium, lithium, barium, strontium, magnesium, and lead plus barium titanate were determined. Additions of all the antimonates except that of magnesium had a depressing effect on the Curie peak of barium titanate, resulting in bodies with dielectric constants of 2000 or less, which showed relatively little variation with temperature. The addition of magnesium orthoantimonate to barium titanate produced a very rapid downward shift in the temperature of the Curie peak. X‐ray studies showed that the antimonates of barium, strontium, sodium, and magnesium, when added to barium titanate in small amounts, formed solid solutions with slightly expanded lattice structures.
A Microstructure Study of Barium Titanate Ceramics
Authors: KULCSAR FRANK
Published: June 2006

Polishing and etching techniques suitable for the metallographic examination of polycrystalline barium titanate ceramics are described. Interpretation of the photomicrographs reveals information which may be correlated with the electromechanical properties.
Domain Twinning in Barium Titanate Ceramics
Authors: COOK WILLIAM R.
Published: June 2006

The patterns found in metallographically prepared barium titanate ceramics are shown to be due to 90° domains. Sets of domains are bounded by (110) planes. Forsbergh's solution of the “square‐net” pattern is confirmed.
Influence of Copper Ions on Adherence of Vitreous Coatings to Stainless Steel
Authors: MOORE D. G. , EUBANKS A. G.
Published: June 2006

An investigation was made of the effect of copper oxide in promoting the adherence of vitreous coatings to AISI type 321 stainless steel. It was found that copper ions in the coating produced a significant increase in adherence on both pickled and sandblasted surfaces but that the effect of the copper decreased with increased firing temperature and increased firing time for the pickled specimens. X‐ray examination of specimens revealed that the copper ions were reduced to metallic copper near the interface during firing; however, examination of sections with the metallographic microscope showed no selective corrosion of the stainless‐steel surface. It was observed that the curve obtained when plotting the copper oxide content of the coating against the adherence index was of the same type as that obtained for cobalt oxide on ingot iron.
The Crystalline Phase in Fluoride Opal Glasses
Authors: ROTHWELL G.
Published: June 2006

The crystalline phases which are present in fluoride opal glasses containing various combinations of divalent oxides have been identified. On the basis of these observations, the occurrence of various fluorides is discussed. The information deduced concerning the relative ease of precipitation of the various cations as fluorides is considered and explained in terms of the part played by such ions in the glass structure. It is shown that, other factors being equal, those ions which may be considered as taking part in the structural network are less liable to form a crystalline fluoride.
A Radioisotope Study of the Nickel Dip
Authors: RICHMOND JOSEPH C. , KIRKPATRICK HARRY B. , HARRISON WILLIAM N.
Published: June 2006

Radioisotope tracer studies of the deposition of nickel during nickel dipping of steel and of the effect of this nickel deposit on the reduction of cobalt ions to metallic cobalt during enamel firing showed the following: (1) The deposition of nickel on the metal surface during the dipping and the deposition of cobalt at the enamel‐metal interface during firing were both markedly affected by the type of cleaning given the steel and by the mechanical deformation of the metal surface. (2) The nickel from the nickel dip remained as metal at the interface during firing of the enamel. (3) The presence of the nickel deposit had little or no effect on the deposition of cobalt at the interface during firing.
Calibration of Pyrometric Cones
Authors: BEERMAN H. P.
Published: June 2006

Pyrometric cones produced by the Standard Pyrometric Cone Company (now known as The Edward Orton, Jr., Ceramic Foundation) were calibrated at the National Bureau of Standards in 1926. Cones available from the 1926 calibration were recalibrated, and new working standards were obtained by calibrating specimens of present production from the Orton Foundation. Heating rates of 150° and 60°C. per hour were used in determining the end points of a series of large cones, whereas a rate of 300°C. per hour was employed for the small cones through cone 12. The pyrometric cone equivalent (P.C.E.) series was calibrated and extended down to cone 12

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Role of Domain Processes in Polycrystalline Barium Titanate
Authors: McQUARRIE MALCOLM
Published: June 2006

The theory of magnetic domains is reviewed and a comparison is made with the ferroelectric case. The known facts regarding domain processes in barium titanate are summarized and an attempt is made to apply these facts to the formulation of mechanisms for several electrical processes in ceramic barium titanate. It is suggested that the initial (low alternating field) dielectric constant of the material is due mainly to induced polarization, with some contribution (about 20%) from 90° domain wall motion, a mechanism which makes a much larger contribution to the dielectric losses at 1000 cycles. The poling process (to make the material piezoelectrically active) is visualized as a removal of 180° domain walls, with only a temporary motion of 90° domain walls. The aging process is thought to be due to the removal from the dielectric polarization of the contribution of the 90° wall motion.
Flaw Distributions and the Variation of Glass Strength with Dimensions of the Sample
Authors: GREENE CHARLES H.
Published: June 2006

The phenomena associated with the fracture of glass are more logically expressed by a distribution function giving the probability of failure when the tensile stress at a point reaches a given value than by the concept of an intrinsic strength which is a characteristic of the material. In practice it is found that this distribution function has appreciable values only on the surface of glass. Functional equations are developed relating the results to be expected in tension tests and in modulus of rupture tests with one or two loading edges on cylindrical rods. Experiments with acid‐polished rods of Pyrex‐brand chemical glass require a two‐term distribution function dn= (2.9 × 10−9S2+ 7.15 × 10−21.S8) dS to express the results found by a bending test with one loading edge (units, kilograms and millimeters), whereas results given by Bailey for lime‐glass rods not polished are expressed by the function dn= 7.3 × 10–32 (units, pounds and inches) for tests with two loading edges.
Specular‐Gloss Measurement of Ceramic Materials
Authors: NIMEROFF I. , HAMMOND H. K. , RICHMOND J. C. , CRANDALL J. R.
Published: June 2006

A standard specular‐gloss method is required to achieve duplicability between laboratories for the wide range of gloss found in recently developed porcelain enamels. A decision was made to standardize on the gloss scale resulting from the geometry of the 45″ gloss attachment of the Hunter multipurpose reflectometer. As the source and receiver apertures of this instrument were not readily measurable, a goniophotometer was adjusted so that its scale duplicated that of the Hunter instrument. The source and receiver apertures of the adjusted goniophotometer were measured and these were recommended to glossmeter manufacturers for inclusion in the design of their instruments. Significant improvement in the duplicability of specular‐gloss measurements resulted, as evidenced by the measurement of 45″ specular gloss of a large number of ceramic specimens having a wide variety of surface‐appearance characteristics. The recommendations resulting from this investigation have been incorporated, with slight modification, into gloss tests for porcelain enamels proposed by the Porcelain Enamel Institute and the American Society for Testing Materials.
Elastic Moduli of Glasses at Elevated Temperatures by a Dynamic Method
Authors: SPINNER SAM
Published: June 2006

The elastic constants of thirteen glasses were measured by a dynamic method at elevated temperatures. Both Young's modulus and the shear modulus were determined and from these Pois‐son's ratio was calculated as a function of temperature. Fused silica, Vycor‐brand glass, and Pyrex‐brand glass had positive temperature coefficients of elastic moduli, whereas all the other glasses showed negative coefficients. Poisson's ratio was found to rise with temperature in all thirteen glasses. This is interpreted as an indication of an approach to the liquid state.
Durability of Deaired Brick
Authors: McBURNEY J. W. , JOHNSON PAUL V.
Published: June 2006

The applicability to deaired brick of the durability gradings in the current American Society for Testing Materials Specifications C 62 and C 216 was questioned because of the lack of data on the properties and weathering resistance of de‐aired brick. The production of 14 plants producing deaired brick was accordingly sampled, and determinations were made on representative subsamples of such properties as transverse and compressive strength, water absorptions by 24‐hr, cold immersion and by 5‐hr, boiling, and the derived saturation coefficients. Representative subsamples were also subjected to the action of weather in the exposure test plot maintained at the National Bureau of Standards and relations between measured properties and the effect of weathering for five years were considered. The effect of lamination and other types of nonhomo‐geneity on weathering was also noted. It was concluded that the current specifications apply to both deaired and nondeaired brick.
The Relation of Viscosity, Nuclei Formation, and Crystal Growth in Titania‐Opacified Enamel
Authors: YEE TIN BOO , ANDREWS A. I.
Published: June 2006

This investigation shows that there is a relationship between viscosity, number of nuclei, and crystal growth during the firing of titania‐opacified enamels. This agrees with a similar relationship which Tammann found in his experiments with organic glasses. The history of the development of the size, shape, and relative number of particles per unit area of titanium dioxide crystals was traced from 650° to 1300°C. As the temperature increased from 700° to 1100°C., the color of the specimens viewed under reflected light changed from light blue to white and then to cream‐white. The methods used in this investigation were the measurement of viscosity, X‐ray analysis, differential thermal analysis, and the study by light microscopy and electron microscopy of very thin heat‐treated films which had been produced by blowing bubbles from high‐temperature melts.
Effect of Certain Organic Liquids on Strength of Glass
Authors: MOORTHY V. K. , TOOLEY F. V.
Published: June 2006

This investigation was undertaken to determine the effect of certain organic liquids on the strength of glass. Constricted glass rods 10 to 12 mils in diameter were broken under various organic liquids and the strength changes were noted and compared with breakage under water. In all cases except one (nitrobenzene), breaking strengths were higher under the organics than under water, ranging from increases of 36 to 19% for alcohols to values of 10 for heptane, benzene, and toluene. The value of 10 is equivalent to breakage in air. It is believed that the polar character of an organic liquid, its molecular bulk, and its solubility in water are significant factors in its effect on the strength of glass.
Antimony Oxide Glasses
Authors: HEDDEN WALTER A. , KING BURNHAM W.
Published: June 2006

Glass compositions containing antimony oxide as a glassformer were developed. The stabilizing oxides used in these compositions were A12O3, Na2O, and K2O. Glasses formed from these oxides, containing antimony oxide in amounts up to 78% by weight, transmitted infrared radiation in wave lengths up to 6.2 μ. The compositional range and some properties of these glasses are given.
Investigations of Stresses in Glass Bottles Under Internal Hydrostatic Pressure
Authors: TEAGUE J. M. , BLAU HENRY H.
Published: June 2006

The behavior of glass bottles under internal hydrostatic pressure has been studied. Three commercial beer bottle designs were investigated by four different methods of experimental stress analysis, namely, photoelastic, electric strain gauge, brittle coating, and brittle model methods. The “fixation” or “stress‐freezing” method of three‐dimensional photoelastic stress analysis employing Fosterite models has been applied to the study of glass bottles apparently for the first time. By this method extensive measurements of the surface stress distributions have been made and are presented in graphical form. Other tests corroborate these results and illustrate the characteristics of bottles under internal pressure, including the effects of certain elements of bottle design. Results obtained by all four methods correlate well and should find valuable and practical applications in similar studies on other types of glass containers
Effect of Sulfur Dioxide Atmospheres on Efflorescence
Authors: MIKE T. M. , BROWNELL W. E.
Published: June 2006

The effect of sulfurous atmospheres on the efflorescence of structural clay materials was studied. An efflorescing shale and a nonefflorescing clay were fired in 5 and 0.5% sulfur dioxide atmospheres. The efflorescing tendency was determined by a wick‐action type of test, and the efflorescing salts were analyzed by microchemical techniques. The effects of additions of calcium carbonate and magnesium carbonate to the nonefflorescing material were studied. Sulfate development in the drier was investigated by drying specimens in a sulfurous atmosphere. Efflorescence was obtained on specimens prepared from a normally nonefflorescing material when this material was fired in a sulfurous atmosphere; the efflorescence tendency was increased, however, by drying in an atmosphere containing sulfur dioxide.
An Impact Test for Use with Cermets
Authors: SOXMAN EDWIN J. , TINKLEPAUGH JAMES R. , CURRAN MARTIN T.
Published: June 2006

Several specimens of a commercially produced nickel‐bonded titanium carbide cermet were tested in eight laboratories at room temperature and at 1800°F. by an increment‐type impact test in which the specimens were held as a cantilever in a vise and were subjected to repeated blows of increasing intensity at their free ends. The inconsistent results obtained were attributed to differences in (1) vise jaw insert material and design, (2) vise gripping pressure, or (3) the stress condition of the specimen at elevated temperatures as contrasted with that at room temperature. A different increment‐type impact test was developed and was used for evaluating the low‐velocity impact behavior of cermets as a function of temperature. In this test the specimens were supported at their ends and were subjected to impact loading at their midpoints by a freely falling hammer. Hot tests were conducted on specimens heated by means of their electrical resistance. The test was modified, by the addition of a miniature muffle furnace, for testing electrical insulators at elevated temperatures. It was established that increment impact tests, when used with metal‐bonded cermets, are subject to a repeated‐blow effect; i.e., low‐energy blows contribute not only to recoverable elastic deformation but also to some permanent damage. In spite of this complication, the new test has been tentatively accepted for use by several cermet research laboratories.
Fundamental Thermal Deflection Analysis of Enamel‐Metal Systems
Authors: LAUCHNER J. H. , COOK R. L. , ANDREWS A. I.
Published: June 2006

The deflection‐temperature relationship of enameled metal strips was automatically recorded on a function plotter from 25° to 600° C. The thermal expansions of enamels and metal were correlated with the observed deflection produced by the composite. Metal and coating thicknesses were related to deflection, and corresponding stress values were calculated.
Effect of Temperature on Modulus of Elasticity of Porcelain Enameled Steel
Authors: COWAN R. E. , ALLEN A. W. , FRIEDBERG A. L.
Published: June 2006

The modulus of elasticity of porcelain enameled steel specimens was measured at different temperatures. A dynamic test (the sonic method) was used for the determination of the modulus of the metal and of the metal‐enamel composites. Equations and constants are presented by which the elastic constant can be calculated for any enamel thickness in the temperature range from room temperature to 500° C. Graphs are also presented to show the relationship of the modulus of elasticity, temperature, and enamel‐metal thickness ratio for ground‐coated, white cover‐coated, and direct white enameled steel specimens.
Dynamic and Static Tests for Mechanical Properties of Fired Plastic Refractories and Other More Resilient Materials
Authors: MONG L E. , PENDERGAST W. L
Published: June 2006

An apparatus for loading brick‐sized specimens and a sensitive deflectometer are described. For a resilient material, the dynamic test, the static shear‐free transverse test, and the static shear‐corrected transverse test gave the same modulus of elasticity. The resilient materials were dense firebrick, glass, steel, and plaster. The elementary shear correction was satisfactory for the correction of the deflections of transverse test specimens having length‐to‐depth ratios ranging from 3.2 to 7.2. The dynamic modulus of elasticity, the static secant modulus of elasticity, and the static modulus of rupture were obtained for nine brands of heat‐treated plastic refractories. The load‐deflection curves obtained from static tests on these materials indicated plastic deformations ranging from nil to 19% of the truly elastic deformations calculated from the results obtained by the dynamic method of test. The differences in the extensibilities calculated from the static and dynamic methods of test were equivalent to these plastic deformations. For studies of thermal spalling, the static extensibilities were preferred because they approximated the strain at rupture.
Compressibility of Binary Alkaline‐Earth Borate Glasses at High Pressures
Authors: WEIR CHARLES E. , SHARTSIS LEO
Published: June 2006

Compression data to 10,000 atm. were obtained for a series of barium, strontium, and calcium borate glasses at 21°C. The compressibility was found to be in the order Ba > Sr > Ca at corresponding molar concentrations and was not appreciably affected by pressure in the experimental pressure range. Comparison of data on alkali and alkaline‐earth borate glasses shows that the compressibility at corresponding molar concentrations is smaller in the alkaline‐earth glasses. Numerical comparisons at appropriate compositions show that a large part of the decreased compressibility produced by the alkaline‐earth oxides arises from electrovalent sources.
Ceramic Ultrasonic Magnetostrictive Transducer
Authors: ROOT H. D. , McDONALD J.
Published: June 2006

The magnetic and magnetostrictive properties of cobalt and nickel ferrite were investigated. Sample making and testing procedures are described. A method of evaluation of a biased magnetostrictive transducer is demonstrated. A comparison is made between nickel metal and nickel ferrite which shows that the ferrite may compare favorably for some applications.
Phase Equilibria in High‐Alumina Part of the System CaO–MgO–Al2O3–SiO2
Authors: DeVRIES R. C. , OSBORN E. F.
Published: June 2006

Results are presented of a study of phase equilibria among crystalline and liquid phases in the quaternary system CaO–MgO‐Al2O3–SiO2 at Al2O3 contents greater than 35%. Equilibrium diagrams shown are for the five triangular joins CaAl2Si2O3‐Ca2Al2SiO7‐MgAl2O4, Ca2Al2SiO7‐MgAl2O4‐Al2O3, CaAl2Si2O8‐MgO‐Al2O3, CaAl2Si2O8‐Mg2SiO4‐MgAl2O4, and CaAl2Si2O8‐MgO‐Mg2SiO4. The composition and nature of the four quaternary peritectic points and the relationships of univariant lines and primary phase volumes are discussed.
Physical Effects of Auxiliary Fluxes in Aluminum Enamels
Authors: KAUTZ KARL , MICHELOTTI JOSEPH E. , HOUSLEY W. LEAS
Published: June 2006

Auxiliary flux additives to milled enamels for aluminum must serve (a) as an inhibitor or alkali “buffer” in enamel‐metal reactions and (b) as a flux to aid rapid enamel fusion during the early stages of firing. Raw and fritted mixtures were varied in two milled aluminum enamels. The effects of these mixtures on the physical properties, drying and firing characteristics, and water spalling resistance are tabulated. Results indicate that the proper balance between alkali, B2O3, and SiO2 functions best to meet these requirements.
Morphology of Fractures in Polished Glass Surfaces
Authors: LEVENGOOD W. C. , FOWLER W. E.
Published: June 2006

A moisture‐condensation technique previously described was utilized in a study of the effect of polishing on fracture patterns in glass surfaces. The experiments show that the apparent controversy concerning the polishing out or “bridging over” of surface fractures may be resolved on the basis of crack dimensions. If the fracture width is less than 1/4 λ, it may be sealed over by polishing, even though the depth may be 1 mm. or more. A modified condensation chamber was devised to show in detail the effect of aging and fracture growth in polished surfaces.
Effect of Ammonium Salts on an Illitic Shale
Authors: BAULEKE M. P. , DODD C. M.
Published: June 2006

The effects of additions of urea, monobasic ammonium phosphate, dibasic ammonium phosphate, sodium ammonium phosphate, ammonium nitrate, and ammonium chloride on some physical properties of an unfired and a fired illitic shale of high carbonate content were studied. X‐ray examination of the Devonian shale showed that illite was the predominant clay mineral; there was also some chlorite. Scum was reduced and a clean surface was produced by additions of ½ to 1% of ammonium phosphate. Urea did not reduce scum. Ammonium nitrate and ammonium chloride increased scum. Fired absorption was increased by monobasic ammonium phosphate, ammonium chloride, and ammonium nitrate, whereas dibasic ammonium phosphate, sodium ammonium phosphate, and urea produced only slight changes. The workability of the tempered shale was decreased by 1% additions of monobasic ammonium phosphate, ammonium chloride, and ammonium nitrate. The presence of the chloride or the nitrate ions caused thixotropy and the phosphate ion caused dilatency. All ammonium additions shortened the time for complete oxidation of the shale specimens. Ammonium chloride was the best oxidation accelerator. Only the 1% addition of ammonium chloride increased the frost resistance of specimens fired to cone 07. All specimens fired to cone 02 were frost resistant and ammonium additions had no effect. The hydration of lime on specimens fired to cone 07 was not affected by additions of ammonium salts, Firing to cone 02 reacted most of the free lime and held hydration to a minimum.
Unsteady‐State Method of Measuring Thermal Diffusivity and Biot's Modulus for Alumina Between 1500° and 1800°C.
Authors: PALADINO A. E. , SWARTS E. L. , CRANDALL W. B.
Published: June 2006

An unsteady‐state method was employed for measuring values of Biot's modulus and the thermal diffusivity of pure dense alumina in the temperature range 1500° to 1800°C. Limits were established for the possible range of values of diffusivity, and corresponding values of thermal conductivity were calculated.
Note on Thermal Expansion and Microstresses in Two‐Phase Compositions
Authors: KINGERY W. D.
Published: June 2006

Thermal expansion data for W–MgO and AlSiO2 compositions are not simply averages of end‐member values but agree quantitatively with calculations based on the assumption of substantial residual microstresses resulting from the restraint of each phase on cooling.
Determination of Sulfur in Glass
Authors: WILLIAMS J. P. , FARNCOMB F. J. , MAGLIOCCA THERESA S.
Published: June 2006

The total sulfur in glass in the range 0.01 to 1.0% SO3 can be rapidly estimated by an induction furnace combustion method using standard commercial equipment. The results compare favorably with the classical barium sulfate precipitation procedure and with X‐ray fluorescence analysis. The sulfide sulfur in glass can be determined by solution of the sample with hydrofluoric acid in the presence of silver ion, followed by titration of the amount of silver precipitated.
The Mechanism of Filter Pressing and Slip Casting
Authors: ADCOCK D. S. , McDOWALL I. C.
Published: June 2006

The literature on the mechanism of the slipcasting process is reviewed. An equation is developed to give a quantitative description of the rate at which the clay layer is deposited from the slip in the filter‐pressing and slip‐casting processes. Certain factors in the equation can be evaluated by the application of the Kozeny equation. Agreement between the calculated and observed rates of solids deposition is satisfactory and confirms that the mechanism in both processes is simple dewatering.
High‐Temperature Glazing of Alumina Bodies
Authors: FISHER EUGENE , TWELLS ROBERT
Published: June 2006

The chief problems in glazing alumina bodies at high temperatures are (1) high porosity of the body with high capacity for absorption at the glaze‐fusion temperature, (2) difference in thermal expansion between body and glaze, and (3) chemical activity of body and glaze materials. It is preferable to use feldspathic glazes with the RO group composed of alkalis from high‐potash feldspars augmented if necessary by small amounts of potash frits. The effects of varying alumina and silica, with the RO group composed entirely of alkali, are illustrated for a typical glaze field. The glazes were applied to four alumina bodies containing 0 to 30% clay. The specimens were fired to cone 18, one‐fire and two‐fire. The results show that the area of best glazes was centered around 1.0 RO, 1.5 Al2O3, 15.0 SiO2 and 1.0 RO, 1.75 Al2O3, 15.0 SiO2 for one‐fire and two‐fire glazing, respectively.
Diffusion of Argon in a Potassium‐Lime‐Silica Glass
Authors: REYNOLDS M. B.
Published: June 2006

Diffusion coefficients for bulk diffusion of argon in a potassium‐lime‐silica glass have been determined at temperatures in the range 308° to 470°C. by a radioactive counting technique. Argon diffusion was found to follow classical bulk diffusion theory within the limits of experimental accuracy. From a plot of log D versus 1000/T, an activation energy of 42 kcal. per mole was obtained for the argon diffusion process. The activation energy and diffusion coefficients obtained for argon by the radioactive counting technique are compared with values for helium and argon obtained by other investigators by use of the permeation technique.
Practical Particle‐Size Analysis of Clays: I, Sample Preparation
Authors: PHELPS G. W. , MAGUIRE S. G.
Published: June 2006

Wide variations in particle‐size data from different laboratories for the same clay were thought to be due to dissimilar preparatory techniques. It was proposed to attempt to establish universally acceptable conditioning procedures based on determination of deflocculant requirement, most effective electrolyte, and method of dispersion. Three commonly employed dispersing agents were tested over a range of percentages on four selected whiteware clays. Both high‐intensity agitation and low‐intensity stirring were tried. It was found that all the sodium polyphosphate salts tested were equally effective and that with them complete dispersions could be attained by a minimum of agitation. Electrolyte requirements for complete dispersion were found to relate directly to points of minimum viscosity of deflocculated 50% clay‐water slips.
Effect of Firing Schedules on Stress‐Temperature Relations in Enamel‐Metal Systems
Authors: LAUCHNER J. H. , COOK R. L. , ANDREWS A. I.
Published: June 2006

The effect of box and continuous enameling furnace firing schedules on the thermal deflection of enameled iron strips was studied. Effective coefficient of thermal expansion values were calculated from coefficient of thermal deflection data. Results indicate that the effective thermal expansion values for annealed and unannealed enameled iron agree with the expansion data obtained by an interferometer study of the same enamels. Variation in the cooling rate of the enameling furnaces studied is sufficient to produce a marked change in the development of thermal stress in the enameled iron. Residual compressive stresses in the enamel are increased by rapid cooling from firing temperatures. Tensile stress developed in the enamel during reheating is reduced by previous annealing.
Predicting the Thermodynamic Stabilities and Oxidation Resistances of Silicide Cermets
Authors: SEARCY ALAN W.
Published: June 2006

Available information on the thermodynamic stabilities of transition metal silicides is summarized and is used to demonstrate the calculation of the stability of silicide‐metal mixtures. The cause of the outstanding oxidation resistance of certain silicides is analyzed, and the results are used to predict high oxidation resistance for several untested disilicides. Thermodynamic and structural arguments are applied to the prediction of compositions of thermodynamically stable and oxidation‐resistant cermets.
Studies in the System (Ba, Ca, Pb)TiO3
Authors: McQUARRIE MALCOLM
Published: June 2006

The weight loss, dye absorption, crystalline phase or phases, dielectric constant, dissipation factor, and temperature variation of dielectric constant were determined for various bodies in the system (Ba, Ca, Pb)TiO3 fired in an air atmosphere at temperatures from 800?° to 1400°C. The per cent of PbO loss is proportional to e−B/T, where B is a constant and T is the absolute temperature. It is possible to fire most bodies in this system to zero (visual) dye absorption, but the sensitivity of the dissipation factor to moisture shows that some bodies are not well fired in the electrical sense. The electrical properties correlate well with the crystalline constitution. The two‐phase region of the barium‐calcium titanate binary extends into the ternary to about 35 mole %, lead titanate.
Verification of Use of Peak Area for Quantitative Differential Thermal Analysis
Authors: de Josselin de Jong G.
Published: June 2006

The amount of reacting material in a sample investigated by differential thermal analysis can be determined from the peak area according to the Boersma equation, which accounts for heat flow through sample and thermocouple wires. This relation has been checked by experiment and it has been found that the use of different thermocouples for the calibrations may lead to variations of about 30%. The values obtained for heat transfer through a sample and thermocouple have been checked by comparison of computations and observation of base‐line offset at the beginning of a run and exponential decay of the amount of heat dissipating out of a sample. It is shown that according to the equation it is not the total amount of reacting material that determines the peak area but merely the density of the material near the thermocouple. The sensitivity of the method for quantitative analysis is discussed in relation to the possible variations in the factors involved, namely, density and heat conductivity of the sample and heat transfer through the thermocouple.
Characteristics of Refractory Oxide Coatings Produced by Flame‐Spraying
Authors: AULT NEIL N.
Published: June 2006

Many ceramic materials can be applied as coatings by flame‐spraying rods made from these materials. Aluminum oxide coatings, stabilized zirconia coatings, and zircon coatings have been studied in detail with regard to their structure and their physical and thermal properties.
Crystal Chemistry of Hydrous Calcium Silicates: I, Substitution of Aluminum in Lattice of Tobermorite
Authors: KALOUSEK GEORGE L.
Published: June 2006

Mixtures of 0.8 moles of CaO per mole of SiO2 plus Al2O3 were prepared from lime, kaolin, and tripoli (microcrystalline quartz); the amounts of SiO2 to Al2O3 were varied to give from 0.2 to 20.7% Al2O3 by weight of dry solids. After hydrothermal treatment (170° to 175°C.), the products were examined by differential thermal analysis and by X‐ray diffraction. A homogeneous solid identified as the mineral tobermorite (4CaO.5SiO2.5H2O) and containing up to 4 or 5% Al2O3 was obtained. Increasing the amount of Al2O3 in the raw mixture above about 5% resulted in the formation of the hydrogarnet 3CaO.Al2O3.SiO2.4H2O as a second phase. Allowing for the Al2O3 combined in this solid, it was indicated that slightly more Al2O3 was substituted in the tobermorite as the amount was increased in the raw mixture. It is suggested that the Al3+ ions probably assume tetrahedral coordination when substituting for the Si4+ ions.
Two Peaks in the Internal Friction as a Function of Temperature in Some Soda Silicate Glasses
Authors: FORRY K. E.
Published: June 2006

Measurements of the internal friction of the glasses 17% Na2O‐83% SiO2, 25.6% Na2O‐74.4%, SiO2, and 34% Na2O‐66% SiO2 were made as a function of temperature, composition, and frequency in the range 1 to 3 cycles per second and from –90° to 500°F. The internal friction as a function of temperature revealed two distinct peaks for each glass tested. One peak occurred in the temperature range −55° to +50°F. and the other in the range 300° to 500°F. All the observed peaks were found to be best represented by an assumed Gaussian distribution of heats of activation with the high‐temperature peaks exhibiting a much wider distribution than the low‐temperature peaks. It was therefore concluded that none of the peaks was a manifestation of a single heat of activation. The temperatures at which all peaks occurred increased with increasing frequency. From this shift of “peak” temperatures with frequency, the most likely heats of activation associated with each peak were calculated. The temperature dependence of the dynamic shear modulus for each glass was used to calculate the “relaxation strength” of the relaxation process for each peak. An analysis of all these data strongly indicated that the high‐temperature peaks as well as the low‐temperature ones were related to cooperative action among sodium ions.
Structural Interpretation of Immiscibility in Oxide Systems: I, Analysis and Calculation of Immiscibility
Authors: LEVIN ERNEST M. , BLOCK STANLEY
Published: June 2006

Crystal chemistry principles are applied to the quantitative interpretation of immiscibility in nineteen binary and eight ternary glass systems. Using ionic radii and one of two coordination types, two methods are given for the calculation of immiscibility in binary systems. The additive density method gives agreement with experimental results in both the borate and silicate systems to within about 5 mole %. The oxygen‐volume method agrees, in general, to within 2 mole %. The maximum extent of immiscibility in ternary borosilicate systems can also be calculated. The importance of the electrostatic bond strength, defined as the valence divided by the coordination number, is discussed in relation to shape of liquidus curve, cation coordination type, and charge distribution on the network‐former tetrahedra. Implications of the analysis to the structure of glass are presented.
Sintering of Alumina at Temperatures of 1400°C. and Below
Authors: CUTLER IVAN B. , BRADSHAW CYRIL , CHRISTENSEN CARL J. , HYATT EDMOND P.
Published: June 2006

Previous investigators have indicated that both small particles and the addition of certain oxides promote the sintering of alumina at temperatures below 1700°C. By utilizing combinations of oxides and small particle size, the sintering temperature of 96% alumina bodies was reduced in this investigation to the 1300° to 1400°C. range. It is proposed that this low‐temperature sintering is aided by the formation of a liquid phase. Thin sections of the alumina sintered at low temperatures revealed bodies with small grain size whose bulk densities were above 3.80 gm. per cc.
Immiscibility Area in the System TiO2–ZrO2–SiO2
Authors: DON McTAGGART G. , ANDREWS A. I.
Published: June 2006

A furnace for use in conjunction with the X‐ray spectrometer was developed which was capable of heating small powdered specimens in air to temperatures as high as 1850°C. This furnace was also used for the heating and quenching of specimens in air from temperatures as high as 1850°C. An area of two liquids coexisting between 20 and 93 weight % TiO2 above 1765°± 10°C. was found to exist in the system TiO2–SiO2, which is in substantial agreement with the previous work of other investigators. The area of immiscibility in the system TiO2–SiO2 was found to extend well into the system TiO2–ZrO2–SiO2. The two liquids were found to coexist over a major portion of the TiO2 (rutile) primary‐phase area with TiO2 (rutile) being the primary crystal beneath both liquids. The temperature of two‐liquid formation in the ternary was found to fall about 80°C. with the first additions of ZrO2 up to 3%. With larger amounts of ZrO2 the change in the temperature of the boundary of the two‐liquid area was so slight as to be within the limits of error of the temperature measurement. Primary‐phase fields for TiO2 (rutile), tetragonal ZrO2, and ZrTiO4 were found to exist in the system TiO2–ZrO2–SiO2. SiO2 as high cristobalite is known to exist in the system TiO2–ZrO2–SiO2.
Thermal Decomposition of Lead Carbonate
Authors: PERETTI E. A.
Published: June 2006

The thermal decomposition of PbCO3 powder was measured at low eating rates under controlled pressures of CO. The solid phases formed by three stages of decomposition were found to be PbO.PbCO3, 2PbO.PbCO3, and PbO, in the order of increasing temperature. For each reaction a log p versus l/T plot of the data resulted in a straight line.
Black Coring in Structural Clay Products
Authors: BROWNELL WAYNE E.
Published: June 2006

The formation and removal of black cores in structural clay products was studied to provide the industry with a broader understanding of this defect. Analytical procedures indicated that carbonaceous matter was responsible for the formation of black cores, but the properties of the core were actually dependent on the state of oxidation of the iron. For the removal of black cores, time, temperature, and kiln atmosphere were varied to find the optimum conditions for core oxidation. Such conditions were found at higher temperatures than were usually recommended and with more excess air than was heretofore thought necessary. Ammonium compounds were incorporated into clay bodies to assist in core oxidation. The action of these reagents was found to be more mechanical than chemical. Ammonium chloride and ammonium hydroxide increased the porosity of the ware in such a way as to allow a better penetration of oxygen into the center. These additions greatly accelerated the oxidation of clay products, but they did not substitute for atmospheric oxygen. The experiments conducted indicated the importance of cooling as an oxidation period.
Reaction Between K2O and Al2O3‐SiO2 Refractories as Related to Blast‐Furnace Linings
Authors: McCUNE S. E. , GREANEY T. P. , ALLEN W. C. , SNOW R. B.
Published: June 2006

An examination was conducted to determine the mechanism of peeling of fire‐clay brick in the low‐temperature region of a blast furnace where 3 to 10% K2O is the principal contaminant. In laboratory tests, as‐received high‐duty and superduty fire‐clay brick and 70% alumina brick treated with KCl‐K2CO3 mixtures showed no peeling at a temperature of 1600°F. Cracks were found in high‐duty brick that were treated with KCN at 1500°F. under partially reducing conditions. X‐ray diffraction studies of mixtures of crushed brick and K2CO3 indicated the formation of leucite (K2O.Al2O3.4SiO2) and kaliophilite (K2O.‐Al2O3.2SiO2) at temperatures below 1700°F. These latter data, confirmed by specimens from used blast‐furnace linings, showed that silica is the first constituent attacked by alkali. Since the formation of leucite and kaliophilite in fire‐clay brick is the probable cause of peeling, the increased reaction of silica, in a dense Al2O3.SiO2 refractory of higher silica content than fire‐clay brick, should confine the alkali attack to the surface of the brick in low‐temperature applications.
Microstructure of Barium Titanate Ceramics
Authors: DeVRIES R. C. , BURKE J. E.
Published: June 2006

The microstructure of polycrystalline barium titanate as seen in polished and etched specimens is more complicated than that in the single crystal. The greater complexity is revealed in the form of a banded structure which is considered to be due to the stress configuration arising from mutual impingement of randomly oriented grains during the cubic‐tetragonal phase transformation.
Stability of the Aluminum Silicates
Authors: FLOOD H. , KNAPP W. J.
Published: June 2006

From the ternary phase diagrams of Al2O3–SiO2 with CaO, MgO, or FeO, it can be concluded that the free energies of formation of kyanite, andalusite, and sillimanite, according to the reaction Al2O3+ SiO2= Al2O3.SiO2, are of the order of magnitude of 0 to –10 kcal. rather than the previously accepted value of –40 to –45 kcal. However, this result may be expected from the general variation of free energies of formation with the ionic potential of the silicate‐forming cation; this conclusion is supported by a plot for some silicates, carbonates, and sulfates.
Melting Relations of the Common Rock‐Forming Oxides
Authors: SCHAIRER J. F.
Published: June 2006

Geological science is concerned with the nature of the materials of the earth and particularly with the processes by which earth materials have been changed and modified. Laboratory studies of the melting behavior of the common rock‐forming oxides have been an important adjunct to the observations of the field geologist. For the past fifty years investigators at the Geophysical Laboratory have been obtaining quantitative information on the melting relations of many of the important rock‐forming minerals. These studies of the fundamental chemistry of igneous and metamorphic rocks have yielded much information of value to ceramists, metallurgists, and mineral technologists. This paper summarizes the most important phase‐equilibrium studies of unary, binary, ternary, quaternary, and portions of quinary systems of the common rock‐forming oxides‐SiO2, Al2O3, FeO, Fe2O3, CaO, MgO, Na2O, and K2O.
Crystal Chemistry of Hydrous Calcium Silicates: II, Characterization of Interlayer Water
Authors: KALOUSEK GEORGE L. , ROY RUSTUM
Published: June 2006

Examination of tobermorite, 4–SCaO.5SiO2.‐5H2O, and xonotlite, 5CaO.5SiO2.H2O, by infrared absorption revealed striking structural similarities and differences in the two phases. In the 8‐ to 15‐μ region, the absorption was the same for both; the differences arose from the manner in which water and hydroxyl ions were bonded. Tobermorite exhibited strong absorption at 6.2μ, a band which is generally associated with interlayer water, and at 2.9μ, a band generally attributed to bonded (OH). The mineral xonotlite did not show these two bands but contained the band at 2.75μ generally associated with free (OH). Synthetic xonotlite prepared at 300°C. was essentially the same as the mineral, but samples prepared at progressively lower temperatures exhibited the 2.9‐μ band in increasing intensity. The fibrous form of tobermorite showed a band at 6.5 to 7.0μ which increased in intensity with increasing amount of CaO in the solid; this band was also found in the 14‐a.u. 1.0 CaO: SiO2 hydrate, but not in xonotlite. The great volume stability of xonotlite during drying and wetting is readily explained on the basis of the present results. Shrinkage of tobermorite during drying at temperatures up to 650°C. may be due to removal of both interlayer water and bonded (OH). The changes in absorption during drying at room temperature were too small, however, to permit drawing any conclusions. Similarities and differences between tobermorite and certain clays are discussed.
Thermal Stresses Around a Heated Hole in a Large Glass Plate
Authors: THOMPSON A. C.
Published: June 2006

The problem of sealing a hole in a cool glass plate under conditions at or above annealing temperatures is examined. By use of the well‐known equations for stresses in thin circular disks and the application of proper boundary conditions, the concept of a negative temperature distribution (a method of superposition used in stress analysis) that will represent the cooling leads to the conclusion that, under these conditions, the stress in the glass near the hole is independent of the temperature distribution around the hole and dependent only on the physical constants of the glass and the temperature of the lateral surface of the hole.
V2O5‐O pacified White Enamels
Authors: SMALLEY A. K. , KING B. W. , DUCKWORTH W. H.
Published: June 2006

Whiteness and opacity were developed in lead borosilicate enamels by additions of 3 to 8 weight % of V2O5. These enamels were characterized by their fusibility, maturing at 1125° to 1200°F. Compositions were adjusted to provide fit and adherence to both glass and aluminum. Normal methods of preparing, applying, and firing were employed. Some of the experimental enamels for glass had marginal resistance to hot alkali solutions. Others appeared to be suitable for general‐purpose enamels, for which the chemical requirements are not so stringent. The enamels for aluminum, for which acid and weather resistance are desirable, were rated as having class A acid resistance, according to the classification system of the Porcelain Enamel Institute.
Magnetic Properties and Associated Microstructure of Zinc‐Bearing Square‐Loop Ferrites
Authors: PALMER G. G. , JOHNSTON R. W. , SCHULTZ R. E.
Published: June 2006

Zinc oxide was added to square‐loop ferrite compositions in order to obtain a lower coercive force and higher magnetic saturation induction than that usually possible from standard commercial square‐loop ferrites. Curie temperatures, hysteresis loops, initial permeabilities, magnetization curves, and switching times for these zinc‐bearing square‐loop ferrites were determined, and representative curves of these parameters are given. Grain structure and etchpit density were also studied, and typical photomicrographs are presented. Zinc oxide can be added to square‐loop ferrites to great advantage, but if too much is added, the useful magnetic properties degenerate completely.