bluuebunny/crossref_metadata_2025 huggingface dataset:
High‐Temperature Reactions of Clay Mineral Mixtures and Their Ceramic Properties: II, Reactions of Kaolinite‐Mica‐Quartz Mixtures Compared with the K2O— Al2O3—SiO2 Equilibrium Diagram
Authors: BRINDLEY G. W. , MARONEY DOROTHY M.
Published: June 2006

Two series of mixtures containing respectively 15 and 35% quartz, together with kaolinite and muscovite in varying proportions, were fired at 1000°, llOO°, 1200°, and 1300°C. for 2‐hour periods. The resulting crystalline phases were measured quantitatively by X‐ray diffraction and the amount of noncrystalline material was estimated by difference. The results for samples fired to 1300°C. are compared with data calculated from the K2O‐Al2O3‐SiO2 equilibrium diagram, and a general agreement is obtained with the calculated equilibrium relations for this temperature. In particular, the observed and calculated amounts of mullite agree within 5%. The main departure from equilibrium is the persistence of unreacted quartz, and consequently the estimated amount of noncrystalline residue tends to be less than the calculated liquid (viz. glassy) component. At 1100° and 1200°C., the fired materials approach less closely to the equilibrium relations. The decomposition products of muscovite are discussed in an appendix.
Hot Pressing of Fused Silica
Authors: VASILOS THOMAS
Published: June 2006

The hot pressing of powdered fused silica at temperatures below the melting and devitrification regions is described. The fabrication of high‐density shapes of fused silica is possible by this process. A relation expressing densification as a function of viscosity, time, applied pressure, and initial compaction is essentially substantiated.
Hot Pressing of Aluminum Oxide
Authors: MANGSEN G. E. , LAMBERTSON W. A. , BEST B.
Published: June 2006

The hot‐pressing characteristics of two aluminum oxides were studied in order to acquire a better understanding of the densification process and to develop a method of predicting the effects of experimental conditions other than those actually tested. A rapid hot‐pressing technique was developed which greatly reduced the time element. The rate equation proposed by Murray, Livey, and Williams for hot‐pressing ceramics was found to hold for the two aluminas, thus making it possible to predict the effects of changes in hotpressing conditions. The equation used was . Viscosity, η, was calculated as a function of temperature using this equation and the experimental hot‐pressing results. Values varied from 1.2 × 1012 poises at 1300°C. to 4.6 × 1010 at 1600°C.
Apparatus for Measuring Thermal Conductivity of Ceramic and Metallic Materials to 1200°C.
Authors: SUTTON W. H.
Published: June 2006

A steady‐state apparatus for measuring thermal conductivity by a direct method, viz., water calorimetry, is described. The accuracy of measurement is about 1 to 3% in the temperature range 30° to 30O°C. and about 3 to 10% in the range 300° to 1200°C. The samples are rods 9 in. long and in. in diameter, although smaller sizes can be accommodated. One feature of the design is that the sample thermocouples can be plugged into the unit. Curves for samples of alumina, stainless steel, and graphite are included.
Effect of Aspect Ratio and Viscosity Gradients on Flow Through Open Channels
Authors: COOPER A. R.
Published: June 2006

The effect of aspect (height to half width) ratio on flow through open channels is considered by evaluation of St. Venant's solution. Near the center line, flow through moderately wide channels is unatrected by the side walls. Therefore, analytical solutions for the single‐dimension case of flow above a flat plate are determined. They reveal that until viscosity differentials are extreme, the velocity distribution is relatively insensitive to viscosity gradients. With several simplifying assumptions the temperature distribution and the corresponding viscosity field in a cross section of the melting end of a glass tank can be calculated. This permits a numerical solution of open‐channel flow for conditions appropriate to a glass tank. Calculated temperature and velocity distributions are presented for three values of the ratio of effective thermal conductivity of glass to thermal conductivity of refractory. Applications of this type of information to glass‐tank technology are briefly discussed.
A Study of Commercial Periclases
Authors: HUBBLE D. H. , DODGE N. B.
Published: June 2006

Nine commercial periclases were studied chemically, physically, and petrographically. One of the periclases was made from magnesite, one from brucite, three from sea water, and four from brine. The magnesia content ranged from 88 to 98%, and the bulk density ranged from 3.01 to 3.28 gm. per cc. Wide variations were found in the mineral placement of the silicates within each periclase. The variation of silicate content and magnesia‐crystal size within well‐sintered periclase has indicated that rotary kilns can be used to produce periclase of higher purity than the current product.
The Kinetics of Gamma‐Ray Induced Coloring of Glass
Authors: LEVY PAUL W.
Published: June 2006

When glasses are colored by ionizing radiation the induced optical absorption increases as the radiation progresses and appears to be due to the superposition of a number of individual absorption bands. A detailed study of this process has been made using a specimen of Corning boro‐silicate glass colored by exposure to 60Co gamma rays. This particular sample was chosen because only four bands are formed. If it is assumed that each band is Gaussian shaped the spectrum may be separated into four absorption bands. The peak energy E0 and full width U of these bands are, in electron volts: E0= 4.85, U= 1.19; E0= 3.95, U= 1.30; Eo= 2.58, U= 0.58; E0= 2.02, U= 0.52. For each band growth curves may be constructed showing how the density of absorption centers increases as a function of dose. These growth curves have been fitted with theoretical curves based on the following considerations: the radiation field creates ionization electrons in the glass; for each ionization electron one electron deficient region or hole is formed; absorption bands observed are due to centers formed by electron trapping although the possibility that some of the bands are due to hole trapping is not ruled out; and competition for ionization electrons exists between holes and the various kinds of electron traps. Satisfactory agreement between the observed and calculated curves is obtained. The theory indicates that the “radiation protection” imparted to glass by materials such as CeO2 may arise in several different ways and that it would be possible to decide between them from rather simple experiments.
A Gamma‐Ray Induced Absorption Band in Some Lead Borate Glasses
Authors: BISHAY ADLI M.
Published: June 2006

Observations made on some lead borate, lead aluminoborate, and lead boroaluminosilicate glasses have shown that an absorption band is induced at 1.5 e.v. (825 mμ) by gamma irradiation. Experimental evidence indicates that this band is associated with Pb2+ ions and boron in the structure of these glasses. On replacing PbO by Tl2O in a borate glass, two strong bands were observed; one band corresponds to the 1.5 e.v. band induced in lead borate glasses and a completely new band at 1.0 e.v. (1235 mμ). A postulate for the center responsible for the absorption band at 1.5 e.v. is proposed.
Dissociation Pressures of Solid Solutions from Fe3O4 to 0.4Fe3O4·0.6CoFe2O4
Authors: CARTER R. E.
Published: June 2006

The dissociation pressures of solid solutions from Fe3O4 to 0.4Fe3O4·0.6CoFe2O4 have been determined as a function of temperature. Within experimental error, solid solutions within this range are thermodynamically ideal.
Dilatometric and X‐Ray Data for Lead Compounds, I
Authors: ARGYLE J. F. , HUMMEL F. A.
Published: June 2006

Linear thermal‐expansion data are presented for lead silicate, lead phosphate, lead borosilicate, and lead silicophosphate compounds. X‐ray powder data for the compounds are given, and previous phase equilibria and X‐ray data are discussed briefly.
Oxygen Mobility in Polycrystalline NiCr2O4 and α‐Fe2O3
Authors: KINGERY W. D. , HILL D. C. , NELSON R. P.
Published: June 2006

Oxygen diffusion coefficients have been determined for polycrystalline samples of NiCr2O4 and α‐Fe2O3 by exchange measurements with oxygen gas containing the stable isotope18O, using mass spectrometer analysis. Oxygen diffusion in NiCr2O4 can be represented by the equation D = 0.017 exp (‐65,400/RT); oxygen diffusion in α‐Fe2O3 can be represented by the equation D = 1 × 1011 exp (‐146,000/RT). The large difference between D0 and activation energy for these materials suggests that different diffusion mechanisms are involved.
Application of Thermoluminescence and Reflectance Methods to Study of Lattice Defects in Alumina Ceramics
Authors: ATLAS LEON M. , FIRESTONE ROSS F.
Published: June 2006

Alumina ceramics irradiated with gamma rays emit light of varying intensity as they are warmed. The resulting glow curve may be resolved into discrete peaks, each of which corresponds to a separate electron trapping level. The energy depth of each trap may be estimated from the glow‐peak temperature and the temperature at which the light intensity reaches half its maximum value. Resolved glow curves are presented for a series of alumina ceramics including specimens having less than 100 p.p.m. of impurities as well as others contaminated with low concentrations of Si, Ti, Fe, Mg, and Ca oxides. Curves are also given for high‐purity aluminas which were heated in oxygen and in hydrogen after firing. Where possible, glow peaks are identified with the causative impurity ion or annealing treatment, and estimated trap depths are tabulated. Because of its inverse relation to optical absorption, reflectance is also sensitive to changes in the number and type of lattice defects. Annealing in oxygen and introduction of Ca2+ ions produce a significant lowering of the reflectance of irradiated alumina ceramics, whereas exposure to hydrogen has the opposite effect.
Internal Friction of Simple Alkali Silicate Glasses Containing Alkaline‐Earth Oxides: II, Interpretation and Discussion
Authors: RYDER ROBERT J. , RINDONE GUY E.
Published: June 2006

The results of internal friction measurements on simple three‐component glasses that were reported in Part I of this paper are discussed. From a consideration of the basic equations governing internal friction and examination of the results of other investigators, a basis of interpretation is developed. It is shown that changes in peak‐temperature position can be explained by changes in the activation energy of the process causing the peak. A change in peak height not accompanied by a change in the shape of the peak is shown to be due to a change in the concentration of the relaxation mechanisms. Using this information the changes in the peaks due to composition variations are explained on a structural basis. A mechanism is also suggested to explain the new high‐temperature peak. A critical examination of the measurements on alkali‐free and phosphate glasses leads to the conclusion that it may be necessary to re‐evaluate some of the concepts concerning the low‐temperature peak in alkali silicate glasses.
The Iron‐Oxygen Equilibrium in Glass: Effect of Platinum on the Fe2+/Fe3+ Equilibrium
Authors: BAAK T. , HORNYAK E. J.
Published: June 2006

A number of experiments were performed on iron‐containing sodium disilicate melts in air. It was found that it was not possible to obtain an equilibrium between Fe2+ and Fe3+ in platinum crucibles owing to the reaction between platinum and iron, whereas in alumina crucibles the equilibrium was rapidly established. Thermodynamic calculations of the reaction 2FeO (in Na2O‐2SiO2) +½O2 (g) = Fe2O3 (in Na2O‐2SiO2) showed that the equilibrium went more and more to the right with increasing temperature. The standard free energy, enthalpy, and entropy for the reaction were calculated.
New Electron‐Optical Data on the Kaolinite‐Mullite Transformation
Authors: COMER J. J.
Published: June 2006

A technique is described for preparing fired kaolinites for examination by electron diffraction and electron microscopy. Specimens fired on platinum foil at 850° and 950°C. were etched while on the foil in 10% sodium hydroxide for 1 week and were then removed by a two‐stage collodion‐carbon replica. The etching is believed to have removed free silica which is formed during the transition from metakaolin to the cubic spinel‐type phase. Electron diffraction patterns show the (111) orientation of the spinel‐type structure on thea‐bplane of the metakaolin. Patterns of specimens at 950° C. show that the mullite phase is oriented with thecaxis parallel to the [110] axes of the spinel‐type phase as proposed by Brindley and Nakahira. Particle size of the spinel‐type phase estimated from electron micrographs appears to fall within 75 to 125 a.u. Kaolinites varying in degree of crystallinity are being studied by this method.
Formation and Strength of Magnesia Whiskers
Authors: HULSE CHARLES O.
Published: June 2006

The formation of single‐crystal magnesia whiskers during the compressive deformation of single crystals at room temperatures is described. These whiskers can have strengths of the order of millions of pounds per square inch. They are formed during fracture as a result of the discontinuous propagation of cracks which are mechanically relieving internal stresses resulting from plastic flow
Fundamentals of Glass‐to‐Metal Bonding: VI, Reaction Between Metallic Iron and Molten Sodium Disilicate
Authors: HAGAN LUCY G. , RAVITZ S. FREDERICK
Published: June 2006

Molten sodium disilicate was found to react with iron powder in vacuum in the temperature range 935° to 1000°C. Under these conditions Fe reacted with Na2O in the glass to form Na gas and essentially FeO in the glass.
Electrical Properties of Single‐Crystal and Polycrystalline Alumina at High Temperatures
Authors: PAPPIS J. , KINGERY W. D.
Published: June 2006

The electrical conductivity of single‐crystal and polycrystalline aluminum oxide has been measured over the temperature range 1300° to 1750°C. and at oxygen partial pressures of 10° to 10−10 atmospheres. Alumina exhibits p‐ type conductivity at high oxygen pressures and n‐type conductivity at low oxygen pressures. The variation of conductivity with temperature depends on the specimen purity, oxygen pressure, and temperature level. Activation energies varying between 2.6 and 5.8 e.v. were found. The conductivity of alumina does not result from any single simple process over wide ranges of temperature and oxygen partial pressure. Apparently intrinsic conduction is found for single crystals at temperatures above 1600°C.
Studies of Reactions Between Uranium Dioxide and Graphite
Authors: CRAVEN B. , McCARTNEY ERIC R.
Published: June 2006

Some work is described that was carried out on the reactions which took place when uranium dioxide and graphite were heated together in an inert atmosphere at temperatures up to 2130°C. Rates of the reactions taking place at the interface between the two reactants were determined and were found to follow a parabolic rate equation.
High‐Temperature Reactions of Clay Mineral Mixtures and Their Ceramic Properties: III, Shrinkage and Porosity in Relation to Initial Mineralogy
Authors: BRINDLEY G. W. , MARONEY DOROTHY M. , UDAGAWA S.
Published: June 2006

Little exact information exists on the relation of mineralogical composition of clay materials to their properties after firing. Property‐composition diagrams are constructed for linear shrinkage and apparent porosity of quartz‐kaolinitemica mixtures fired at 1100° and 1200°C.; contours of equal shrinkage and equal porosity are derived. Sixty natural clays and shales are analyzed semiquantitatively for mineral content, and their shrinkage and porosity values are obtained after firing to 1100° and 1200°C. The ceramic properties of the natural materials are compared with those of the prepared mixtures. Conclusions are drawn regarding the influence of mineralogical composition on the ceramic properties. The mica content is shown to be particularly important because of its role in the for mation of a glassy component.
Studies in Lithium Oxide Systems: X, Lithium Phosphate Compounds
Authors: TIEN T. Y. , HUMMEL F. A.
Published: June 2006

As a preliminary to the investigation of the ternary systems Li2O‐B2O3‐P2O5 and Li2O‐SiO2‐P2O5 the existence of the previously reported lithium ortho‐, pyro‐, and metaphosphate compounds was confirmed. A rapid, reversible inversion takes place in Li4P2O7 at 630°C. New data on the melting points, optical properties, and X‐ray diffraction patterns of each of the compounds were obtained.
Growth of Barium Ferrite Single Crystals
Authors: GAMBINO R. J. , LEONHARD F.
Published: June 2006

A study has been made of the growth of barium ferrite single crystals from a sodium carbonate flux. Crystals weighing up to 5.6 gm. have been grown by cooling melts slowly from about 1250°C. The phase diagram of the system BaO‐Na2O‐Fe2O3 has been studied in the region of the BaFe12O19 composition. The effects of variations in batch composition, heating cycle, and seeding have been studied from the point of view of crystal yield and quality.
Glass Scintillator for Neutron Detection
Authors: BISHAY ADLI M.
Published: June 2006

A glass scintillator which can be used as one of the main components of a slow‐neutron time‐of‐flight spectrometer has been developed. This sodium aluminoborate glass containing 73 mole % B2O3 and 8.0 mole % Ce was melted under highly reducing conditions in a series of cerium‐activated very high boron‐containing glasses. This glass is water white with very high light transmittance for wave lengths greater than 3800 a. u. It has a neutron‐detection efficiency which is 25 to 30% greater than any other known glass scintillator in the energy range 102 to 104 e.v. and is considerably better than any other type of detector. It was found that the neutron pulse height increases with increasing cerium content up to a maximum and then decreases with further increases in the cerium content. The molar content of cerium required to obtain a maximum pulse height for each B2O3 concentration increases linearly with the increase in the B2O3 content. However, the maximum pulse height decreases gradually with the B2O3 content from 17.0 arbitrary units at 54.5 mole % to 6.7 at 73.4 mole %. This lower pulse height is still considerably above the photomultiplier noise at room temperature.
Electron Microscopic Studies of Growth Structures in Hexagonal Ferrites
Authors: DROBEK J. , BIGELOW W. C. , WELLS R. G.
Published: June 2006

Electron microscopic studies of sintered hexagonal ferrites have revealed growth structures which indicate that crystal growth from a relatively highly saturated vapor phase occurs above certain temperatures during the sintering process. Illustrations of variations in the growth structures at various locations in the ferrite are given, and the probable importance of the vapor‐phase growth mechanism in the over‐all sintering process is discussed.
Control of the Properties of Glazes by the Aid of Eutectics
Authors: WATTS ARTHUR S.
Published: June 2006

The alkaline earth‐boric oxide‐silica systems are especially important in the compounding of ceramic glazes and bodies because they enable the introduction of B2O3 in an insoluble form. Published equilibrium eutectics and other low‐temperature invariant points were investigated regarding temperatures and rates of deformation. Most of these compositions were found to be soluble in acid, alkaline, and phosphate solutions; tests in distilled water at 195°F. for 5 days therefore were chosen as the means of selecting the compositions which would be practical for use in the development of ceramic glazes. The systems BaO‐B2O3‐SiO2, CaO‐B2O3‐SiO2, and SrO‐B2O3‐SiO2 were studied first separately; the insoluble composition highest in B2O3 in each system was chosen for the triaxial study of the system alkaline earth‐boric oxide‐silica as a source of B2O3 in glazes and perhaps as a B2O3‐bearing frit in ceramic bodies. Each of these insoluble glasses was also studied for the effect of limited change in composition on softening temperature and rate of deformation.
Mechanism of Secondary Expansion of High‐Alumina Refractories Containing Calcined Bauxite
Authors: McGEE THOMAS D. , DODD C. M.
Published: June 2006

The use of some calcined bauxites in high‐alumina refractories is limited by unusual and excessive secondary expansion. One such calcined bauxite was compared with pure alpha alumina to determine the crystalline changes responsible for the expansion, to determine the mechanism of the expansion, and to suggest means for control of the expansion. X‐ray diffraction and petrographic techniques were used. The expansion was found to result from crystallization of secondary mullite by the action of impurities in aiding the diffusion of alumina and silica. Secondary mullitization and growth began at 1400°C. and caused as much as 23% expansion at 1600°C. The expansion was caused primarily by the mullite growth rather than by the true density changes associated with mullitization. Small sodium fluoride additions proved to be effective for controlling expansion.
Relations Between Heat Losses of Glass, Forming Times, and Bottle Production in Blowing Machines
Authors: GIEGERICH W.
Published: June 2006

The critical review of production numbers and forming times of different glass‐container machines is a problem of technical and economic importance that is recognized in nearly all glassworks. An exact technical and scientific investigation of these forming times is not possible because of (a) the limited knowledge of the heat transfer and flow of glass, (b) the great difficulties encountered in making measurements of the process, and (c) the influence of ordinary variations in the plant. Some simple relations between the timetable of operations and heat losses of glass during the forming process are given. Quite exact data for heat losses and operating times permit the assignment of standard values which characterize the special properties of the glass during forming.

V. Summary

Critical judgment of the capacities and forming times of various glass‐processing machines is a task that has to be carried through almost daily in glassworks, since it is closely‐related to the necessity of finding out the best way of operation. An exact technical and scientific evaluation of the forming times is hardly possible for the following reasons: (a) the meager knowledge of heat transfer and flow during forming, (b) the great, nearly insurmountable difficulties with respect to the technical problems of measurement, and (c) the variety of the manifold operational influences. Therefore an attempt has been made to describe in simple relations the chronological sequence of the individual operations of the forming process, and the cooling of the glass during the process. On the basis of exact time studies of the individual operations, and with the aid of many calorimetric measurements of the heat rates in the individual forming stages, which were made on numerous fully automatic blowing machines, one can, by means of classification and comparison of the findings, set up approximate operational values. It is hoped that such an analysis has afforded some new ideas and suggestions concerning the technical principles of fully automatic bottle blowing.
Comparison Between Heat‐Transfer Conditions and Setting Up of Strain in Glass During Heat‐Treatment
Authors: ACLOQUE PAUL
Published: June 2006

The properties of transparency and artificial anisotropy in glass were utilized in making a film recording of the development and evolution of thermal strains in glass specimens undergoing rapid cooling or heating. Discussed as examples are the traditional tempering treatment and the more original “temnization” treatment (to use a word coined by the writer several years ago). The mean temperature of the specimens was measured during these treatments by a calorimetric method, and from the representative curve of the mean temperature the temperature distribution at each instant throughout the specimens was deduced by calculation, using simple hypotheses. It was then possible to compare the distribution curves of strain with the distribution curves of temperature and from this comparison to explain certain phenomena such as the existence of conditions for “strain inversion” during tempering and conditions for “strain reversion” during temnization. This investigation is the preliminary stage of a more detailed examination of the behavior of a visco‐elastic body under variable temperature conditions when its viscosity is temperature‐dependent.
Melting Phenomena in the System CaO–SiO2– H2O: I, The Join Ca2SiO,‐Ca(OH)2
Authors: HARKER R. I. , ROY D. M. , TUTTLE O. F.
Published: June 2006

The liquidus‐solidus relations along the join Ca2SiO4‐Ca(OH), in the system CaO‐SiO2‐H2O have been determined at 1000 atm up to 1110°C. This join is binary and contains the calcium silicate hydrate, calciochondrodite, Ca5‐(SiO4(OH)2. Calciochondrodite melts incongruently to Ca2SiO2+ liquid (composition 23 wt% Ca2Si04) at 955°C. The eutectic between calcium hydroxide and calciochondrodite lies at 13% Ca2Si04 and 822°C. Preliminary experiments, also at 1000 atm, in the ternary system CaO‐Ca2Si04‐Ca(OH), indicate that the eutectic at which the fields of primary Ca(OH)2, CaO, and Ca2(Si04)2(OH)2 meet is close to the CaO‐Ca. (OH), side of the triangle at approximately 805° C. The ternary reaction point Ca2SiOl+ liquid ⇌Ca5(SiO4)2(OH)2+ CaO + liquid is believed to lie in the low‐CaO (<5%) high‐Ca(OH)2 (>70%) part of the system.
Application of Czochralski Crystal‐Pulling Technique to High‐Melting Oxides
Authors: NASSAU K. , BROYER A. M.
Published: June 2006

The Czochralski technique of pulling from the melt has been extensively used in the field of semiconductors. The criteria for its applicability are discussed and indicate that this technique should also be applicable to some of the high‐melting ceramic oxides and oxide compounds. In addition to the successful growth of large crystals of calcium tungstate, preliminary experiments were performed on several other oxides. A number of materials including ferrites, rutile, and barium titanate have been grown in single‐crystal form, and growth conditions are described. Crucible material and atmosphere control problems are also discussed.
Structure‐Controlled Reactions in Kaolinite‐Diaspore‐Boehmite Clays
Authors: BRATTON R. J. , BRINDLEY G. W.
Published: June 2006

Clays containing kaolinite, diaspore, and boehmite are analyzed chemically and mineralogically and their high‐temperature reactions in the range 1000° to 1500°C are followed quantitatively by X‐ray diffraction measurements. It is shown that the development of mullite progresses toward the equilibrium value as the temperature approaches 1500°C. When considered in detail, the reactions reflect the source of the alumina. Diaspore and boehmite first form corundum at widely different temperatures which results in the reactivity of the corundum from boehmite being greater than that from diaspore, and, in consequence, mullite develops more readily from the boehmite‐containing clays. Relative expansions of clays rich in diaspore or boehmite when fired in the range 1200° to 1400°C are correlated with the manner in which mullite forms in this temperature range.
Thermal‐Expansion Anisotropy of Oxide Solid Solutions
Authors: MERZ KENNETH M. , BROWN W. RICHARD , KIRCHNER HENRY P.
Published: June 2006

The effect of solid‐solution atoms on the thermal‐expansion anisotropy of some oxides has been studied as part of a program directed toward the prediction of the thermal‐expansion coefficients of single crystals and single‐phase and polyphase ceramic bodies. The importance of solid‐solution atoms in determining the thermal‐expansion anisotropy of rutile, SnO2, corundum, and Cr2O3 solid solutions has been demonstrated. Vanadium additions to rutile are particularly effective in reducing thermal‐expansion anisotropy. The thermal‐expansion anisotropy was determined by X‐ray diffraction techniques in the temperature range room temperature to 1000°C. Information relating to the extent of solid solution of vanadium in rutile is presented. Research in this area may be important because reduction of thermal‐expansion anisotropy can prevent the formation of microcracks in ceramic bodies, thus leading to stronger bodies.
Dislocations in Rutile as Revealed by the Etch‐Pit Technique
Authors: HIRTHE W. M. , BRITTAIN J. O.
Published: June 2006

Potassium hydroxide and sodium hydroxide were found to be satisfactory for polishing various surfaces of rutile. Dislocation etch pits could be produced by alkali fusions, 85% orthophosphoric acid, and concentrated sulfuric acid. The {l 10}‐, near {111}‐, (001)‐, and {100}‐type surfaces were etched and the etch pits were analyzed in terms of their relation to the deformation systems and crystal symmetry. The correlation between etch pits and dislocations was substantiated by means of matched cleavage surfaces, existence of substructures, generation of dislocations, dislocation densities, and polygonization phenomena. Dislocations were introduced by impacting and macroscopic plastic deformation. Generation of dislocations was observed from 1050°C to as low as room temperature. The slip planes confirmed by means of dislocation traces and slip lines were {110}‐and {101}‐type planes. The slip direction corresponding to the {110)‐type plane was [OO11, the close‐packed direction. The Burgers vector, structure, and motion of dislocations in the edge orientation on the {110) [001] system were determined by analyzing the crystal structure. The Burgers vector was c [001], the lattice translation vector, and the dislocations did not dissociate into partial dislocations. Another possible slip system was the (100) [010] system.
The System Sodium Fluoride—Alumina Investigated by Quenching Methods
Authors: FOSTER PERRY A.
Published: June 2006

Alumina was found to react with sodium fluoride on fusion to produce sodium aluminate and cryolite according to the reaction 6NaF + 2Al22c3= 3NaA102+ Na3A1F6. An insoluble sodium aluminate phase was observed under the polarizing microscope in samples quenched from as high as 1400°C. The equilibrium crystallization temperature of sodium fluoride in the presence of solid sodium aluminate was found to be slightly depressed with added alumina. A maximum lowering of 6°C was found for a starting alumina content of 5.4%. Further alumina additions resulted in the secondary precipitation of β‐Al2O3. The shallow depression of the sodium fluoride crystallization temperature and the observed limited alumina solubility are attributed to the formation of cryolite. The composition of the liquid in equilibrium with sodium aluminate and sodium fluoride or sodium aluminate and β‐alumina is represented in terms of the pseudo‐ternary system NaF‐Al2O3‐Na3A1F6.
Isomorphism Between Sillimanite and Mullite
Authors: ĎUROVIČ SLAVOMIL
Published: June 2006

It is concluded that a continuous isomorphous series can be expected between sillimanite and 2/1 mullite. The formation of individual members of this series depends on the temperature and pressure conditions used. At 1 atm pressure the members between 3/2 and 2/1 mullite are stable; 2/1 mullite is not a structurally distinct mineral, so the separate name praguite for it is unnecessary.
Thermal Conductivity of Refractory Brick
Authors: RUH EDWIN , McDOWELL J. SPOTTS
Published: June 2006

Thermal conductivity measurements were made on many types of refractory brick including high‐alumina, fireclay, silica, chrome, magnesia, forsterite, zircon, silicon carbide, and insulating brick. These measurements, made with a modified ASTM C 201–47 apparatus, covered mean specimen temperatures of 200° to 2000°F. The results are compared with other published data.
Bond Strength and Elastic Properties of Ceramic Adhesives
Authors: THORNTON H. RICHARD
Published: June 2006

Ceramic or inorganic‐type adhesives, which are relatively resistant to thermal and mechanical shock and can sustain strengths at temperatures up to 1500°F, have been developed. Several alterations of the basic glassy phase were studied to attain optimum adhesion properties. Included were the incorporation of metal fillers and recrystallizable materials and the application of special formulation techniques to the basic glassy phase. The basic physical properties, thermal expansion, residual stress, and tensile strength, were correlated with bond strength. Average tensile strength values of 5000 psi at room temperature and 3000 psi at 800°F were found. The addition of selected covalent‐bonding‐type oxides to a barium borosilicate glass resulted in increased strengths at temperatures above 1000°F. The incorporation of metal fillers improved the physical properties of the basic ceramic adhesives. Recrystallized‐type adhesives would not develop strong cohesive bonds unless a glassy phase was also present.
On the Preparation of Thin Single‐Crystal Films of BaTiO3
Authors: DeVRIES R. C.
Published: June 2006

A study was made of the growth of very thin crystals of BaTiO3 on platinum substrates by means of evaporation of KF from a KF‐BaTiO3 solution. Crystals as thin as 300 A were obtained, but the areal extent was very small (0.2 mm2) for a uniform thickness. The random nucleation on defects located on the substrate appears to be a serious limitation on producing large film area. Growth in a <110> direction resulted in more uniform thickness than growth in the <100> direction. The technique does provide a useful way of retrieving small single‐domain crystals with one electrode attached and may have useful application in microminiature devices.
Phase Relations and Crystal Chemistry in the System Uranium Oxide–Lanthanum Oxide
Authors: HILL DAVID C.
Published: June 2006

Uranium oxide‐lanthanum oxide compositions were investigated to determine the phase relations and crystal chemistry in the system under a variety of experimental conditions. X‐ray diffraction, polished‐section, and chemical analysis techniques were used as tools of investigation. Compositions of known metal atom concentration were subjected to oxygen, air, hydrogen, and vacuum environments at elevated temperatures. The dependence of lattice parameter on a stoichiometry for a U0.5La0.5O1.75+x composition was determined. Cubic fluorite solubility was found over a considerable portion of the system uranium oxide‐lanthanum oxide. Results of lattice parameter measurements, stoichiometry determinations, and microstructure examinations are also presented.
The System MgO–MgAl2O4
Authors: ALPER A. M. , McNALLY R. N. , RIBBE P. H. , DOMAN R. C.
Published: June 2006

In the determination of the liquidus, solidus, and subsolidus of the system MgO‐MgAl2O4 the limits of the solid solution of A1 ions in periclase and Mg ions in spinel were measured. By using both X‐ray diffraction and optical techniques, the maximum periclase solid solution was found at 82 wt% MgO, 18 wt% A12O3 (9.5% A13+) and maximum spinel solid solution at 39% MgO, 61 % A1203 (6% Mg++). Periclase and spinel solid solutions existed stably in easily detectable amounts at temperatures above approximately 1500°C.
The System Manganese Oxide–Alumina in Air
Authors: RANGANATHAN T. , MacKEAN B. E. , MUAN ARNULF
Published: June 2006

The quenching technique has been used to determine equilibrium relations among the various phases in the system manganese oxide‐alumina in air in the temperature range 800° to 1765°C. Three isobaric invariant situations have been determined, as follows: Tetragonal Mn2O3 solid solution, Mn203 solid solution, corundum, and gas (PO2= 0.21 atm) coexist in equilibrium at 881°± 5°C. Tetragonal Mn3O4 solid solution, spinel solid solution, corundum, and gas are the phases present together in equilibrium at 990°± 5°C. Spinel solid solution, corundum, liquid, and gas coexist in equilibrium at 1740°± 10°C.
Preparation and Magnetic Properties of Some Hexagonal Magnetic Oxides
Authors: GORDON IRWIN , HARVEY ROBERT L. , BRADEN R. A.
Published: June 2006

The preparation of nonoriented as well as magnetically oriented specimens of 2MeO · 2BaO·‐6Fe2O3 and 2MeO·3BaO·12Fe2O3 is described. The MeO component is limited to NiO, ZnO, CoO, and CuO and mixtures of these in this discussion. The orienting apparatus and technique employed are briefly described. The magnetic permeability and loss as measured at 250 Mc is shown for many of these prepared compositions. The effect of the orienting magnetic field strength as well as firing temperature on the observed magnetic properties is discussed.
Growth of Yttrium‐Iron Garnet from Molten Barium Borate
Authors: LINARES R. C.
Published: June 2006

It has been found that yttrium‐iron garnet can be grown from solutions of yttrium‐iron garnet and molten BaO·xB2O3. This solvent possesses none of the undesirable properties of the usual solvents in that it is noncorrosive, nonvolatile, and has a specific gravity less than that of yttrium‐iron garnet. These properties make the solvent useful for the usual slow‐cooling growth methods and for controlled growth on seeds. The replacement of Ba with Na, K, Pb, Ca, and Sr will yield yttrium‐iron garnet as will the replacement of B2O3 with V2O5. A definite relation exists between the amount of B2O3 in the solvent and the amount of iron in the crystallized phase; namely, the percentage of iron in the crystallized phase is higher with increased B2O3 concentration in the solvent. The use of this type of phase equilibrium information makes possible an orderly method of selecting solvents for crystal growth.
Method of Measurement of Thermal Diffusivity to 1000°C
Authors: PLUMMER W. A. , CAMPBELL D. E. , COMSTOCK A. A.
Published: June 2006

A non‐steady‐state method of measuring thermal diffusivity is described. The method has been used for measurements on glasses, ceramics, and refractories up to 1000°C with satisfactory results. The choice of a non‐steady‐state method permits simplification of the equipment and the specimen preparation required. In addition, only temperature differences, times, and specimen thickness need to be known. The temperature rise of a flat heating element and that of a heat sink in the medium are measured. For a given thickness and time, the diffusivity is a function of the ratio of the foregoing two temperatures. The applications and limitations of the method are discussed.
Effect of Surface Layers on Mechanical Characteristics of MgO
Authors: GORUM A. E. , MOBERLY J. W.
Published: June 2006

Magnesium oxide single crystals were coated with copper, cobalt, nickel, aluminum, iron, and gold to determine what effect, if any, altering the surface would have on the mechanical strength of the MgO. The coated crystals were given various heat treatments to allow a metal oxide to form on the MgO surface. The specimens were bent, using a three‐point loading machine to determine the flow stress. These geld strengths were then compared. It was found that the iron, nickel, and cobalt oxide layers decidedly lowered the yield strength whereas aluminum, gold, and copper had no effect.
Linear Thermal Expansion of Aluminum Oxide and Thorium Oxide from 100° to 1100°K
Authors: WACHTMAN J. B. , SCUDERI T. G. , CLEEK G. W.
Published: June 2006

The linear thermal expansion of single‐crystal and polycrystalline aluminum oxide and poly‐crystalline thorium oxide was measured from 100° to 1100° K with an interferometric technique. For each substance the results are well described by Gruneisen's equation using a Nernst‐Linde‐mann energy function.
Infrared Study of Compounds and Solid Solutions in the System Lithia–Alumina–Silica
Authors: MURTHY M. KRISHNA , KIRBY ELIZABETH M.
Published: June 2006

The system Li2O‐Al2O3‐SiO2 contains several compounds and solid solutions which are important commercially and which are also of interest from a structural point of view. In addition to the interesting polymorphic modifications exhibited by spodumene and eucryptite, the solid solutions between spodumene and eucryptite and more particularly the solid solutions between spodumene and silica (the so‐called silica‐O series) constitute a group of materials quite suitable for studying the applicability of infrared methods for structural interpretations. The infrared spectra of all the compounds and some typical solid solutions have been obtained and the relations between these spectra and the structures as determined by X‐ray methods are discussed.
Sintering of Zinc Sulfide
Authors: McQUEEN H. J. , KUCZYNSKI G. C.
Published: June 2006

The mechanisms of the sintering of ZnS were determined by measurement of the rate of growth of the necks between polycrystalline spheres. In vacuum (10−6 mm Hg) at temperatures higher than 600° C the mechanism of sintering is that of volume diffusion with coefficient Dv, = 1.06 × 10−2 exp (‐26,400/RT); below 600°C surface diffusion predominates, with coefficient D3, = 9.14 × 10‐3 exp (‐5700/RT). In Zn vapor (10−2 mm Hg) between 550° and 650°C the predominating mechanism of sintering is surf ace diffusion, D3, = 7.06 × 10−2 exp (‐8600/RT). It has been found that in an argon atmosphere the diffusion coefficient is much lower.
Study of Mechanism of Reaction Hot Pressing
Authors: ACCARY A. , CAILLAT R.
Published: June 2006

The mechanism of reaction sintering was studied in mixtures of uranium‐uranium sesquinitride and uranium‐silicon. Refractory uranium mono‐nitride of high density may be prepared by hot pressing mixtures of uranium and uranium sesquinitride at 1000°C. Steps of the process are (1) densification of the uranium metal into a continuous uranium matrix and (2) reaction of the uranium sesquinitride with the uranium matrix. On the contrary, during hot pressing uranium‐silicon mixtures react before any densification of the uranium occurs. The pressing temperature required for a given density is then practically the same as for unreacted powders and the previously formed compound. Densification stages of the prereacted compounds may be described by the equations y = aot2/5+ b0, y = a1 log t + b1, and y = a2t−1/2+ b2, where y is the shrinkage and t is the time. The first stage is absent during densification of the powder mixtures.
The System Bi2O,—B2O3
Authors: LEVIN ERNEST M. , MCDANIEL CLYDE L.
Published: June 2006

The phase diagram for the system Bi2O3‐B2O3 has been determined experimentally. The melting point of Bi2O3 has been redetermined as 825° C with an estimated overall uncertainty of about ±3°C, and the molal heat of fusion of Bi2O3, calculated from the slope of the liquidus curve, is 2050 cal per mole. The system contains a body‐centered cubic phase of approximate composition 12Bi2O3·B2O3, which melts incongruently at 632°C. Four congruently melting compounds exist in the system: 2Bi2O3· B2O3·5B2O3, Bi2O3·3B2O3, and Bi2O3·4B2O3, with melting points, respectively, of 675°, 722°, 708°, and 715°C. The Bi2O3·4B2O3 compound exhibits a sluggish transformation at 696°C. Compositions containing up to 97.5 wt% (85 mole %) Bi2O3 can be partly or totally quenched to glass. Indices of the quenched glasses are greater than 1.74. A region of liquid immiscibility extends at 709°C from almost pure B2O3 to 19.0 mole % Bi2O3. The extent of immiscibility theoretically calculated agrees with the experimentally determined value when 1.20 A is used for the ionic radius of Bi3+.
Exchange Behavior of Kaolins of Varying Degrees of Crystallinity
Authors: ORMSBY W. C. , SHARTSIS J. M. , WOODSIDE K. H.
Published: June 2006

Particle‐size fractions of several Georgia kaolins, which were prepared by sedimentation procedures, were examined from the standpoint of crystallinity, cation‐exchange capacity, and surface area. Crystallinity was studied using X‐ray techniques, exchange capacities were measured using the manganese saturation method, and surface areas were determined using glycerol adsorption techniques. A linear relation was obtained between surface areas and exchange capacities when areas were increased by decreasing the particle size or by changing from well‐crystallized to poorly crystallized kaolins. In most cases, the empirically determined crystallinity ratios indicated a change in crystallinity with change in particle size, the crystallinity generally increasing with decreasing particle size in individual samples. Unlike, however, the relation noted for exchange, the crystallinity did not consistently correlate with area changes both among the various samples and within the various particle‐size fractions of a single sample. These results suggest that the relatively high cation‐exchange capacity of poorly ordered kaolins is more directly a result of high surface area with crystallinity playing, at most, a very minor role.
Phase Equilibrium Studies in the System Iron Oxide‐Y2O3–Gd2O3
Authors: VAN HOOK H. JERROLD
Published: June 2006

Equilibrium data at liquidus temperatures are presented for compositions in the quaternary system Y‐Gd‐Fe‐O in ambient atmospheres of oxygen gas (pO2, = 760 mm Hg), air (PO2, = 159 mm Hg), and CO2 (pO2 variable). Incongruent melting occurred in yttrium‐iron and gadolinium‐iron garnet phases and in all intermediate garnet solid solutions in the three oxygen pressure sections studied. Fractionation in the yttrium/gadolinium ratio between oxide liquid and crystalline garnet phases in the quaternary system was not observed experimentally, indicating that unzoned (Y,Gd)3Fe5O12 crystals may be grown from a melt without special precautions to maintain a fixed Y/Gd ratio.
High‐Pressure Hot‐Pressing of Uranium Carbide Powders and Mechanism of Sintering of Refractory Bodies
Authors: CHANG R. , RHODES C. G.
Published: June 2006

Forty‐mesh uranium carbide powders were hot‐pressed in the temperature range 500° to 1500° C under pressures varying from 10,000 to 46,000 atm. Microstructural investigations of the compacts revealed grain‐boundary sliding and fragmentation as important sintering mechanisms.
Phase Relations and Electrical Parameters in the Ferroelectric‐Antiferroelectric Region of the System PbZrO3–PbTiO3‐PbNbO2O6
Authors: DUNGAN R. H. , BARNETT H. M. , STARK A. H.
Published: June 2006

Characteristics of temperature and field‐induced ferroelectric‐antiferroelectric phase transitions are reported as a function of composition. The ferroelectric compositions were found to exhibit remanent polarizations of the order of 30 μcoul per cm2, coupled with low dielectric constants and piezoelectric response. Evidence is presented for the existence of a polymorphic transition in the ferroelectric rhombohedral region of the system PbZrO3‐PbTiO3 and the existing phase diagram modified accordingly.
X‐Ray Study of Quartz‐Cristobalite Transformation
Authors: CHAKLADER A. C. D.
Published: June 2006

The transformation of quartz at 1560°C was investigated by X‐ray techniques. The effect of particle size (and grinding) on the integrated peak intensities of the quartz powders was evaluated. The formation of a so‐called nonquartz layer of preferably nonquartz phase on quartz crystals was encountered after 5 hours of grinding. The present investigation substantiated the previous finding that the process of the transformation of quartz to cristobalite is a consecutive reaction involving an intermediate transition phase. Uranium dioxide of 0.64 wt% catalyzed the transformation reaction; it appeared, however, that this catalytic effect was more pronounced in the last stage (i.e. B → C) of the reaction sequence A → B → C.
Calcium Hexaluminate and Its Stability Relations in the System CaO–Al2O3–SiO2
Authors: GENTILE ANTHONY L. , FOSTER WILFRID R.
Published: June 2006

By a combination of solid‐state sintering and quenching experiments the validity of calcium hexaluminate as a stable phase and the extent of its primary field in the system CaO–Al2O3–SiO2 have been established. The size of the primary field is considerably reduced from that suggested by earlier work. The anorthite‐corundum‐calcium hexaluminate invariant point has been relocated at 28.0% CaO, 39.7% Al2O2, and 32.3% SiO2 and at 1405°± 5°C.