bluuebunny/crossref_metadata_2025 huggingface dataset:
Annealing as a Problem in Genetics
Authors: PRESTON F. W.
Published: June 2006

By analogy with the random loss of genes (or the extinction of family trees) in a biological population, it may be possible to compute the random loss of strain (or the extinction of “polarons”) in the process of annealing glass at constant temperature. In the simplest case this leads to a solution indistinguishable from the Adams and Williamson law of annealing, the “polarons” acting as independent individuals. In more complex cases it leads to partial loss of strain, with a finite residual birefringence that cannot be removed, which appears to agree closely with the observations of Hampton (1926) and of Ghering (1950). This involves the co‐operation of “polarons” in pairs or groups.
Compressibility of Vitreous Silica
Authors: SMYTH HAROLD T. , LONDEREE JOSEPH W. , LOREY G. EDWIN
Published: June 2006

To explain the increase of compressibility of vitreous silica with pressure, it is assumed that there is a possibility of bending of the Si—O—Si lines in the structure. Calculations of network energies show that this is a reasonable assumption. Because of the randomness of the glass structure, it is not possible at this time to obtain more than a qualitative agreement between calculated and experimental values.
Hydrothermal Synthesis of Quartz Crystals
Authors: WALKER A. C.
Published: June 2006

Research at the Bell Telephone Laboratories on the problem of growing large single crystals of quartz has now progressed to a point where it is possible to grow crystals weighing more than 1 lb. each in a period of 60 days or less. Equipment now in use includes autoclaves 4 inches in inside diameter and 4 ft. long, weighing about 1150 lb. each. In developing the hydrothermal process used to grow these quartz crystals it has been necessary to solve many problems in the little‐known field of high pressure. The results point to the possibility of growing other types of crystals, and the field of usefulness of this process now appears to be much more extensive than was the case at the beginning of the investigation in 1946. Of prime importance is the fact that crystals grown from solution are likely to be better formed and of more perfect quality than those grown from the melt or by other methods. Many of the difficulties inherent in this work have been due to corrosion of steel in alkaline solution. This was a rather unexpected problem, since in high‐pressure steam boilers alkali is added in small amounts to prevent corrosion of the boiler tubes. Such corrosion has been shown to be responsible for the appearance of electrical twinning on the growing faces of the quartz crystals. Other causes of such twinning have also been found in the course of this work.
X‐Ray Study of Glass Fibers
Authors: BANERJEE BHUPATI KUMAR
Published: June 2006

Glass fibers of different glassforming oxides, containing small amounts of gold, platinum, or silver halide, have been investigated by the X‐ray diffraction method to find a correlation between the diffraction bands and the glass composition. The degree and nature of crystallization in relation to the aging period of the various glass samples has also been studied. The investigations have revealed the presence of oriented crystallites only in the samples of the B2O3 series in which the centrosymmetric character of the diffraction bands is not disturbed at all.
Examination of Refractory Specimens in Reflected Light
Authors: SNOW R. B.
Published: June 2006

The mounting and polishing technique used to prepare a polished section is described and it is shown that the method may fail unless a good metallurgical microscope is used. The logic related to the identification of the constituents is illustrated by examples of SiO2‐Al2O3 refractories after service.
Measurement of Dry Strength of Clay Bodies
Authors: PASK JOSEPH A.
Published: June 2006

Factors affecting the measured modulus of rupture of unfired clay bars were studied. These included the following variables: mixing time and aging of plastic clay; minor modifications in extrusion‐machine design; and span width, rate of load application, and diameter of test bar used in cross‐breaking machine. It was also found that exposure of dry clay bars to atmospheres of increasing per cent relative humidity decreased their strength values significantly.
Fine Annealing of Optical Glass
Authors: LILLIE H. R. , RITLAND H. N.
Published: June 2006

Since the most important characteristic of optical glass is the uniformity of its refractive index, which is itself a function of fictive temperature, any fine annealing treatment must be such as to bring about substantial uniformity in fictive temperature. Methods of accomplishing this are reviewed. In terms of total required time in the annealing process, the most efficient method consists of soaking the glass for a short time at a temperature near the annealing point and cooling at a constant rate to a temperature below the annealing range and at an increased rate to room temperature. Formulas are given for specifying the parameters in the annealing schedule in terms of the final condition of the glass as to stress and index. The several outstanding advantages of this method of annealing are discussed.
Comparison of Two Equations for Calculation of Densities of Glasses from Their Compositions
Authors: HUGGINS M. L. , STEVELS J. M.
Published: June 2006

Two different relationships have been proposed by the authors, individually, for the calculation of the densities of glasses from their compositions. These relationships are here compared with regard to accuracy, composition limitations, relationships between their constants, etc. The Stevels equation is useful in supplying values (accurate to within about 2%) of the density of glasses having a high proportion of network formers (e.g., Si, B, and Al). Whether or not it is applicable, with different constants, when the content of network modifiers (e.g., Na, Ca, and Pb) is high, has not been determined. The Huggins relationship involves more empirical constants, including two which have different values, depending on which of four composition ranges is pertinent. It is considerably more accurate for well‐annealed glasses of accurately known composition. Difficulties arise in applying it to glasses having a high content of network formers other than silicon or to glasses having components for which accurate values of the necessary constant have not previously been deduced. It is interesting to note that the limiting conditions of the Stevels equation lead, at least for the sodium silicate system, to the same breaks of the volume‐concentration curves as found by Huggins. Comparison of the two relationships yields a better understanding of the reasons for the long‐realized fact that the presence of certain elements, such as Li, Be, and Ti, invalidates the Stevels equation.
Stability of Acid‐Resistant Red Porcelain Enamels
Authors: TUNG REY C. , COOK RALPH L.
Published: June 2006

The comparative acid resistance of a series of enamels was determined by the loss‐in‐weight test and by the spot test. The stability of the red color oxide in these enamels was also studied by varying the alumina, fluoride, soda, and potassia contents in the frit. Improved acid resistance was obtained with no alumina and no fluoride in the frit. The stability of the red color was markedly influenced by the fluoride content; the absence of fluoride in the frit gave very poor stability.
Multiple Ion Substitution in the Perovskite Lattice
Authors: ROY RUSTUM
Published: June 2006

An experimental study has been made of the possibilities and limitations of ionic substitution in the perovskite lattice. Especial attention has been paid to those cases in which more than one type of ion occupies any or all the cation and anion positions. A fairly large number of new oxide phases typified by such compositions as KLaTi2O6, Sr2CrTaO6, Ba3NiNb2O9, and BaK‐TiNbO6 have been synthesized and shown to have the perovskite structure. Anion substitution successfully yields compounds with this structure only when it is complete; no mixed‐anion perovskites have been encountered. Few perovskites with anions other than O2‐or F‐have been found. The importance of valence differences in limiting the extent of ionic replacement appears to have been clearly demonstrated.
Sintering and Grain Growth of Alumina
Authors: SMOTHERS W. J. , REYNOLDS H. J.
Published: June 2006

The sintering and grain growth of alumina as a function of the type of impurity (oxide) added was studied. One weight per cent of the impurity was added to a commercial Be‐grained alumina or was coprecipitated with iilcl3 to form hydroxides. Fired shrinkage, bulk density, and apparent porosity measurements were used to correlate sintering with grain growth as observed by the petrographic and electron microscope. Some additives which increased grain growth were believed to enter into solid solution with alumina and to strain the lattice sufficiently to increase material transport greatly. Other additives were believed to produce a glassy phase which would greatly increase surface difusion and resulting grain growth. Some additives decreased grain growth because of the relatively large vapor phase produced by the impurity upon heating which may have been sorbed on the alumina; other additives may have Wed anion vacancies to reduce material transport or may have produced complex anions whose flow or diffusion may have been impeded.
Metal‐Ceramic Interactions:IV, Absolute Measurement of Metal‐Ceramic Interfacial Energy and the Interfacial Adsorption of Silicon from Iron‐Silicon Alloys
Authors: KINGERY W. D.
Published: June 2006

The surface and interfacial energies in the system Ni‐A12O3 md Ni‐ZrO2 were determined at elevated temperatures by means of equilibrium interfacial angle measurements. Coincidental measurements of surface tension and contact angle for iron and iron‐silicon alloys in Al2O3 give values of interfacial energy. Application of Gibbs' isotherm indicates that interfacial adsorption of silicon takes place in this system.
Color and Spectral Transmittance of Amber Bottle Glass
Authors: BACON FRANK R. , BlLLlAN CARROLL J.
Published: June 2006

Because of increased interest in color uniformity among iron‐sulfur amber bottle glasses, a study was undertaken of their color, their spectral transmittance, and the relationship of these properties. It was found that the psychophysical attributes of color (C.I.E. system) as computed from complete light‐transmittance spectra can actually be estimated for iron‐sulfur amber glasses with good accuracy from transmittance at only two suitable wave lengths, 550 and 650 mp. Transmittance at 550 mμ is closely correlated with brightness (C.I.E.) and thus is sufficient to characterize color intensity, which is the most important variable of color quality among commercial amber glasses. There is also fair correlation between transmittance at 550 mμ and transmittance in the ultraviolet. The latter is important in the avoidance of photochemical action on bottled products. Incidental to this work, the transmittances of a large number of glasses were compared with their iron and sulfur contents. Broadly speaking, it was found that transmittance at 550 mp decreases with increasing ferrous iron or with increasing sulfide content. However, this transmittance is affected substantially by other factors, such as gross composition, minor constituents like fluorine, and thermal history, of which no account was taken in the present work. Transmittance at 1050 mp can be correlated closely with ferrous iron content (as determined by chemical analysis) and absorbancy per unit concentration of ferrous iron in carbon‐sulfur ambers is about the same as in green glasses containing no sulfur.
Re‐Evaluation of Glass Viscosities at Annealing and Strain Points
Authors: LILLIE HOWARD R.
Published: June 2006

A review is presented of the early work which led to the present definitions of the annealing and strain points. New tests on the same primary standards, with modem apparatus and corrections applied for expansion, indicate that the definitions should be modified. A recommendation is put forth regarding such redefinitions, by which the viscosities at the annealing and strain points would be 1013.00 and 1014.60 poises, respectively, during cooling at 4°C. per minute.
Oxidation Resistances of Ternary Mixtures of the Carbides of Titanium, Silicon, and Boron
Authors: ACCOUNTIUS OLIVER E. , SISLER HARRY H. , SHEVLIN THOMAS S. , BOLE GEORGE A.
Published: June 2006

Dense compacts of mixtures of Tic, Sic, and B,C were prepared by sintering in an argon atmosphere and by hot pressing. Titanium carbide and B4C reacted during heating to form TiB2. The oxidation resistances of these ternary compacts were determined by the weight gained at 2000°F. in air. Compacts containing 10% B4C, 70 to 50% Tic, and the remainder Sic had superior oxidation resistances. The oxide coating on these compositions consisted of rutile, silica, and an amorphous third phase. A compact composed of 73.5% Tic, 17% silicon, and 9.5% boron was hot‐pressed. It had zero porosity and better oxidation resistance than any other composition tested.
Opacifying Crystalline Phases Present in Zirconium‐Type Glazes
Authors: JACOBS C. W. F.
Published: June 2006

Various zirconium‐type opacifiers were used in a group of glazes maturing in the range cone 04 to cone 11 and the crystalline phase producing opacity in these fired glazes was studied by elevated‐temperature X‐ray diffraction techniques. The results definitely show that zirconium silicate is the major crystalline phase that promotes opacity regardless of the zirconium opacifying agent added. The foregoing conclusion pertains only to the opacifying particle; this should not be construed to mean that other important characteristics of glazes do not vary with the form of zirconium addition. These other aspects will be discussed in detail in another paper.
Elastic Moduli of Glasses by a Dynamic Method
Authors: SPINNER SAM
Published: June 2006

The elastic moduli and speed of sound of twenty‐three optical glasses, a series of Na2O3, CaO3, SiO3, and B2O3 glasses, and some specimens of fused silica were measured by a dynamic method. Each specimen, in the shape of a prismatic bar, was vibrated in four different ways: longitudinally, flexurally on the wide side, flexurally on the thin side, and torsionally. Good agreement was found on Young's modulus as determined by the first three methods. The torsional mode was used to obtain the shear modulus. Statically and dynamically determined values of Young's modulus for six sample glasses also showed good agreement.
Constitution of Bone China: I, High‐Temperature Phase Equilibrium Studies in the System Tricalcium Phosphate—Alumina—Silica
Authors: PIERRE P. D. S. ST.
Published: June 2006

This investigation represents a first attempt to interpret the thermal behavior and constitution of bone china by means of a phase diagram of an idealized system. A consideration of the Tricalcium phosphate‐alumina‐sica phase diagram in relation to the quaternary system lime‐alumina‐phosphorus pentoxide‐silica indicates that the composition of a normally tired commercial bone china body is β‐tricalcium phosphate and anorthite in a siliceous glassy matrix. X‐ray examinations of many such bodies confirm this interpretation. This preliminary investigation indicates the most profitable fields for further research.
Flame Spectrophotometric Analysis of Glasses and Ores: I, Lithium, Sodium, Potassium, Rubidium, and Cesium
Authors: WILLIAMS J. P. , ADAMS P. B.
Published: June 2006

The alkali elements in a wide range of glass and feldspar ore compositions can be rapidly determined with the flame spectrophotometer without making chemical separations. Flame photometer response to lithium, sodium, and potassium seems little affected by the presence of many of the glass constituents in concentration ranges commonly found in commercial glasses. The mean deviation in absolute per cent between chemical and flame photometer analyses for a series of twenty‐nine glass and ore samples is approximately 0.15% for each of the three common alkalis lithium, sodium, and potassium. Evaluation of the rubidium and cesium results was not possible since chemical analyses for these elements were not available.
Resistance of Refractories to Molten Lead‐Bismuth Alloy
Authors: GANGLER JAMES J.
Published: June 2006

In conjunction with studies of the suitability of liquid metals for high‐temperature heat‐transfer systems, an investigation was made to determine the resistance of forty materials–eighteen ceramics and cermets, thirteen refractory metals, and nine high‐temperature alloys–to attack by Pb‐Bi eutectic alloy (44.5% Pb and 55.5% Bi) in a dynamic system at temperatures of 1500° or 2000°F. The experimental apparatus and procedure is described. With the exception of ZrC all the ceramics and cermets were resistant to attack by molten Pb‐Bi eutectic at 2000°F. Of the thirteen refractory metals only arc‐cast molybdenum exhibited resistance to Pb‐Bi at 2000°F. All nine of the high‐temperature alloys had poor resistance at 1500°F.
Constitution of Soluble Phosphate Glasses
Authors: WESTMAN A. E. R. , CROWTHER JOAN
Published: June 2006

Filter‐paper chromatographic methods have been developed which permit the separation and de‐ termination of condensed phosphate anions containing up to four phosphorus atoms per ring and of linear structures containing from one to nine phosphorus atoms per chain. These methods have been used to study the anions produced when soluble sodium phosphate glasses of a range of compositions and methods of preparation are dissolved in water. The analyses are in qualitative agreement with the structure of phosphate glasses proposed by Van Wazer. X‐ray and other evidence is presented which indicates, for the range of compositions studied, that the structures of condensed phosphate anions found in solution correspond to similar structures of condensed phosphates in the glass before dissolution and do not arise during the solution process. The study thus supports the polymer approach to the constitution of glasses for the range of com‐ position studied.
Control of the Properties of Glazes by the Aid of Eutectics A Study of Fusion Behavior and Other Properties of Ceramic Mixtures in the Eutectic Areas
Authors: WATTS ARTHUR S.
Published: June 2006

The area of the phase equilibrium eutectics of ceramic compositions was studied to determine the location of the deformation eutectics. Mixtures of the deformation eutectics then were investigated to disclose the compositions of lowest deformation temperatures and most abrupt fusion.
Relation of Composition to Viscosity of Enamel Glasses
Authors: YEE TIN BOO , MACHIN J. S. , ANDREWS A. I.
Published: June 2006

The changes in the viscosities of a series of enamel glasses which were produced by varying the CaF2, Fe2O3, TiO2, CO3O4, NiO, MnO2, FeSO4, and NiSO4 contents were examined over a range of temperatures which corresponded approximately to normal firing temperatures. Similar studies on the variations in viscosity produced by blending selected hard and soft frits are reported.

Calcium fluoride is a most effective reagent for modifying the viscosity of ground‐coat enamel. The first few additions
Formation of Color Centers in Glasses Exposed to Gamma Radiation
Authors: KREIDL N. J. , HENSLER J. R.
Published: June 2006

Glasses exposed to gamma radiation develop a visible absorption band similar to theF‐band developed in alkali halide crystals. The function of cerium in preventing coloration of glass was studied in detail in an ultraviolet‐transmitting phosphate base glass in which its characteristic absorption could be measured. When visible absorption was thus prevented, radiation still caused a strong absorption in the ultraviolet which was associated with the electronic structure of cerium. On this basis, transition ions of similar electronic structure were introduced. It was found that iron, manganese, cobalt, nickel, vanadium, copper, and, under certain conditions, some other elements do suppress the formation of the visible absorption band formed in the base glass by radiation while forming more or less prominent bands in other spectral regions. Thus the colorless iron phosphate glass remained colorless under radiation and could be considered to be “protected.” Conversely, with cobalt the new band which reached into the visible was relatively intense and stable, suggesting its use to indicate radiation dose.
Thermodynamic Data on Oxides at Elevated Temperatures
Authors: TRIPP HARLAN P. , KING BURNHAM W.
Published: June 2006

An extensive compilation of data on the free energy of formation of oxides is presented in graphic form. From these curves it is possible to obtain the free energy of most ceramic oxides in the temperature range 0° to 2400° C.
Fundamental Study and Equipment for Sintering and Testing of Cermet Bodies: VII, Fabrication, Testing, and Properties of 34 Al2O3‐66 Cr‐Mo Cermets
Authors: SHEVLIN THOMAS S. , HAUCK CHARLES A.
Published: June 2006

The properties of a cermet solid body containing 34% Al2O3 and 66% 80Cr–20Mo alloy (50Al2O3‐50 alloy by volume) are given as firing shrinkage, density, modulus of rupture, tensile strength, stress‐rupture life, modulus of elasticity, oxidation resistance, thermal‐shock resistance, and thermal expansion. It is shown that substitutions of the 80Cr‐20Mo alloy for Cr in a similar cermet developed earlier substantially improved thermal‐shock resistance.
Ultrasonic Absorption in Fused Silica at Low Temperatures and High Frequencies
Authors: ANDERSON O. L. , BÖMMEL H. E.
Published: June 2006

The absorption of high‐frequency (60 kc. to 20 me. per second) sound waves in fused silica shows a large peak at low temperatures (30° to 50°K.). This absorption appears to result from some property of the glassy state since the absorption does not occur in crystalline silica. Data are presented showing the variation of rigidity and internal friction with temperature and frequency. It is shown that the source of the internal friction may be a structural relaxation. Some speculations are made on the nature of the structural relaxation and its relation to the glassy state.
Phase Equilibria in the System BaTiO3—CaTiO3
Authors: DeVRIES R. C. , ROY R.
Published: June 2006

The system BaTiO3–CaTiO3 was investigated from room temperature to 1900°C. by several different techniques. The system is characterized by extensive solid solution with a minimum at 18 wt.% CaTiO3. The extent of solid solution decreases rapidly with temperature from a maximum of approximately 30 wt.% in each end member at 1595°C. The temperature of the cubic‐hexagonal inversion in BaTiO3 is raised very rapidly with additions of CaTiO3. The tetragonal‐cubic inversion in BaTiO3 is lowered slightly to a minimum of 105°C. by the additions of CaTiO3. Within a wide composition region crystals of cubic BaTiO3 solid solution may be grown directly from the melt, and at the minimum from a melt of the same composition.
The Orthosilicate‐Iron Oxide Portion of the System CaO‐“FeO”‐SiO2
Authors: ALLEN W. C. , SNOW R. B.
Published: June 2006

The phase equilibrium diagram has been determined for the liquidus surface of the portion of the system CaO‐“FeO”‐SiO2 between fayalite, dicalcium silicate, wüstite, and lime. Five ternary peritectic points have been located, but no true eutectics have been found. The primary fields of wuUstite and dicalcium silicate cover most of the area studied (ignoring free iron, which is actually the primary phase in all compositions investigated). The boundaries of smaller fields of olivine solid solution, a parallel‐twinned modification of dicalcium silicate, tri‐calcium silicate, lime, and calciowüstite solid solutions also are delineated. X‐ray data show that lime may contain up to 10%“FeO” in solid solution, whereas wüstite may contain as much as 28% CaO in solid solution. Equilibria involving tricalcium silicate explain earlier observations on open‐hearth slags and furnace‐bottom refractories.
A Theory of Differential Thermal Analysis and New Methods of Measurement and Interpretation
Authors: BOERSMA S. L.
Published: June 2006

A new‐type nickel‐block sample holder for use in differential thermal analysis is described. A simple machine to aid in the interpretation of complex curves is suggested.
Phase Equilibria at Liquidus Temperatures in the System MgO‐FeO‐Fe2O3‐SiO2
Authors: MUAN ARNULF , OSBORN E. F.
Published: June 2006

Liquidus temperatures are presented for mixtures in the system MgO‐FeO‐Fe2O3‐SiO2. The standard quenching technique was modified for work under controlled atmospheres of varying O2 pressures. Data were obtained for the temperature range 1159° to 1775°C., and with O2 pressures ranging from 1 to 10‐8.9 atm. Approximate compositions of crystalline phases were determined, and paths of equilibrium crystallization were derived for selected mixtures under idealized conditions. Application of the phase diagrams to steel‐plant refractories problems is indicated.
Reactions Between Aluminum Oxide and Carbon The Al2O3—Al4C3 Phase Diagram
Authors: FOSTER L. M. , LONG G. , HUNTER M. S.
Published: June 2006

A phase diagram of the system A12O3‐A14C3 is proposed. Two intermediate oxycarbides, A14O4C and A12OC, were established. Eutectic melting between alumina and A14O4C occurred at 1840° C. No other low melting was observed. The alumina phase was not corundum but was similar to delta‐alumina. Because of the high reactivity of aluminum carbide and all the intermediate compounds with moisture and oxygen, use of refractories based on the system A12O3‐A14C3 must be limited to applications where these agents are excluded. The behavior of high‐alumina refractories in the presence of carbon is explained.
Effect of Raw‐Material Ratios on Absorption of Whiteware Compositions
Authors: HACKLER W. C. , KRIEGEL W. W. , HADER R. J.
Published: June 2006

The purpose of this paper is to present an efficient and most useful experimental design for multiple‐factor experimentation. The fired absorptions of a series of whiteware compositions are expressed as a function of the composition variables and temperatures. These variables areX1= clay/ flux,X2= clay/flint,X3= nepheline syenite/ feldspar, andX4= firing temperature. This relationship represents the “best” second‐order approximation to the true but unknown relationship between the absorption and the variables. The equation points out the contribution of each variable to the fired absorption as well as the effect of one variable as influenced by a second. The errors associated with each coefficient in the equation are included along with errors of predicted absorptions.
Factors Affecting Strength of Clays in the Temperature Range 110° to 800°C
Authors: SUTTON WILLARD H. , MATSON FREDERICK R.
Published: June 2006

Using a carefully established procedure for the preparation of test bars and for the measurement of the modulus of rupture, the effect of firing temperature on the transverse strength of a Georgia kaolin, Kentucky ball clay, and Missouri fire clay was determined. The kaolin showed the greatest temperature vs. strength sensitivity (‐19% to +50% of the dry strength); it therefore was used in a study of the effect of aging, electrodialysis, and ion exchange on strength‐temperature relationships. Kaolin treated with H2O2 and HC1, and electrodialyzed kaolin with NaCl and CaCl2, was weaker than the untreated clay after being fired at temperatures below 650°C. but was as much as 131% stronger at 800° firings.
Effect of Wollastonite Substitutions in a Semivitreous Dinnerware Body
Authors: VUKOVICH MILAN
Published: June 2006

A study was made of a series of typical semivitreous dinnerware bodies in which increasing amounts of wollastonite were substituted for flint and for equal portions of flint and feldspar. Wollastonite in amounts up to 8% improved the body by greatly reducing the moisture expansion, reducing the firing shrinkage, reducing the maturing temperature, and increasing the modulus of rupture. Three bodies were selected from this study and four additional bodies were formulated on the basis of a commercial composition. These bodies were used in a plant trial. The findings from a number of tests agreed with those of the laboratory and in addition showed that wollastonite improved dry strength and impact strength. On the basis of the entire investigation, the best bodies were obtained when wollastonite was used in the range 1 to 4%.
Studies of Silica‐Structure Phases: I, GaPO4, GaAsO4, and GaSbO4
Authors: SHAFER ELENA C. , ROY RUSTUM
Published: June 2006

In the course of work on all compositions which would probably yield silica‐structure phases, a detailed study was made of the A3+B5+O4‐type compounds with gallium as the trivalent element. Two forms of GaPO4 exist corresponding to quartz and cristobalite; the quartz form has a thermal expansion of the low‐quartz type and no stable α‐β transition is found in this phase. It inverts stably to the cristobalite form at 933°± 4°C. The cristobalite form melts at 1670°C. and the liquid cannot be made to form a glass. The cristobalite form also has a metastable displacive transition at 616°± 2°C. GaAsO4 exists only in a form corresponding to the lowquartz structure. It disproportionates into Ga2O3 and As2O5 at about 1000°C. GaSbO4 could only be prepared in one form corresponding to the rutile structure. The influence of such phases on SiO2 was determined by studying a few mixtures in the system SiO2‐GaPO4. The SiO2 end member appears to admit about 25% GaPO4 into solid solution in the cristobalite phase at the highest temperature. Even under hydrothennal conditions, however, equilibrium cannot be easily attained at the lower temperatures in a few hundred hours. The results are presented in a not‐impossible diagram for the system GaPO4‐SiO2.
Sintering and Grain Growth of Alpha‐Alumina
Authors: CAHOON HAROLD P. , CHRISTENSEN CARL J.
Published: June 2006

The sintering (densification) and grain growth of alumina were studied to determine the effect of the variables raw material, particle size, grinding in acid media, molding pressure, various single additives in different amounts, and firing temperature. Fine grinding promoted sintering and the growth of large grains and caused the grains to be more elongated in habit. Sintering was facilitated by additions of iron oxide, manganese oxide, copper oxide, and titanium oxide, provided the amounts of these oxides and the temperature of firing were within certain bounds. The growth of large grains was facilitated by additions of iron oxide and manganese oxide. Nineteen other additives had no effect or retarded sintering and large‐grain growth. Both magnesium oxide and silica had a marked effect in inhibiting the growth of large grains. The alkali metal oxides, added singly, were especially deleterious to the production of strong alumina bodies. The maximum density and maximum strength of the fired body were attained approximately simultaneously with the onset of large‐grain growth. The habit of the large grains was markedly altered by increasing amounts of each additive; the grains lost their characteristic crystalline shape and became nearly spheroidal particles. It is suggested that two grain‐growth phenomena exist which are independent of each other. One is termed “small‐grain growth” and is associated with densification; the other is referred to as “large‐grain growth” and occurs in certain specimens, depending on the additions to the alumina, after the sintering (densification) is substantially complete.
Sintering of Glass
Authors: KUCZYNSKI G. C. , ZAPLATYNSKYJ I.
Published: June 2006

It has been shown by a simple experiment on the closing of capillary glass tubes on heating that the final stage of sintering of glass particles, manifesting itself in densification of the compact, proceeds by viscous flow caused by surface tension. This effect has been predicted theoretically by Frenkel.
Limitations of the Fictive Temperature Concept
Authors: RITLAND H. N.
Published: June 2006

The fictive temperature formalism, in which the structural state of the glass is characterized by the fictive temperature T, is very useful in the qualitative description of the effects of thermal treatment in the transformation range. Experimental data are presented which show, however, that such a one‐parameter description has only a limited quantitative significance. When samples of a borosilicate crown, glass, annealed at various constant cooling rates, are compared with samples annealed at constant temperature, it is found that a single parameter does not specify all physical properties simultaneously and that the two types of samples differ markedly in transformation‐range kinetic phenomena. Properties studied include density, refractive index, low‐temperature thermal expansion, approach to equilibrium at constant temperature, and thermal expansion during heating in the transformation range.
The System CaO‐Al2O3‐H2O
Authors: MAJUMDAR A. J. , ROY RUSTUM
Published: June 2006

Phase equilibria have been determined in the system CaO‐Al2O3‐H2O in the temperature range 100° to 1000°C. under water pressures of up to 3000 atmospheres. Only three hydrated phases are formed stably in the system: Ca(OH)2, 3CaO·Al2O3·6H2O, and 4CaO·3Al2O3‐3H2O. Pressure‐temperature curves delineating the equilibrium decomposition of each of these phases have been determined, and some ther‐mochemical data have been deduced therefrom. It has been established that both the compounds CaO·Al2O3 and 3CaO·Al2O3 have a minimum temperature of stability which is above 1000°C. The relevance of the new data to some aspects of cement chemistry is discussed.
Phase Relationships in the System CaO—AI2O3—P2O5
Authors: STONE PHILIP E. , EGAN EDWARD P. , LEHR JAMES R.
Published: June 2006

Primary fields of crystallization in the system CaO‐Al2O3‐P2O5 at temperatures from 900° to 1600°C. were determined by the method of quenching. Three ternary eutectics were established: CaO·P2O5‐Al2O3·3P2O5‐Al2O3·P2O5, 2CaO·P2O6‐CaO·P2O5‐Al2O3·P2O5, and 3CaO·P2O6‐2CaO·P2O5‐Al2O3·P2O5. The rate of decomposition of Al2O3·3P2O5 was determined at several temperatures. The boundary was established between the field A12O3·P2O5, which covers about 35% of the ternary diagram, and the fields Al2O3·3P2O5, 2CaO·P2O5, and CaO·P2O5. A portion of the Al2O3·P2O5‐3CaO·P2O5 boundary also was established. A compound with the composition 2Al2O3·3P2O5 did not appear in the system. No calcium aluminum phosphates were found.
The Colors of Platinum, Palladium, and Rhodium in Simple Glasses
Authors: RINDONE G. E. , RHOADS J. L.
Published: June 2006

A study was made of the colors produced by platinum, palladium, and rhodium when they were introduced as their chlorides in alkali silicate, borate, and phosphate glasses. Yellow, pinkish‐yellow, orange, and brown colors in addition to aventurines and grays were observed in the various glasses. Platinum exhibits an interesting behavior in phosphate glasses. Small additions of platinum chloride produce gray colors, whereas larger amounts produce yellow and orange colors. Nucleation by platinum crystals leading to devitrification was observed in some phosphate glasses.
Effect of Particle Size on Bulk Density and Strength Properties of Uranium Dioxide Specimens
Authors: BURDICK M. D. , PARKER H. S.
Published: June 2006

Fused uranium dioxide was separated into fractions of varying particle size by air separation. Specimens of the nominal size of 1/8 by 1/4 by 1½ in. were formed by hydrostatic pressing, firing, and lapping. Specimens prepared from the 0 to 5 μ fraction were the strongest and most dense. The room‐temperature density was about 92% of theoretical and the room‐temperature flexural strength was about 12,000 1b. per sq. in. When tested at 1000°C., the strength was about 18,000 1b. per sq. in. The flexural strength of specimens decreased and their density decreased as the starting particle size was increased. The crystallization of the urania fragments which had occurred during the firing treatment was observed.
Observations on the Stabilization of Zirconia
Authors: WEBER B. C. , GARRETT H. J. , MAUER F. A. , SCHWARTZ M. A.
Published: June 2006

The characteristics of magnesia‐, calcia‐, and ceria‐stabilized zirconia are described. They were determined by two techniques: (1) the National Bureau of Standards high‐temperature X‐ray analysis of sintered specimens and (2) room‐temperature X‐ray analysis of specimens heat‐treated at 1180°C. up to 100 hours. Also reported is an investigation of the ternary system Ti‐Zr‐O, with particular emphasis on the binary systems TiO‐ZrO2 and Ti‐ZrO2. Data are presented on the stability of the compound ZrTiO4 and on the inability to confirm the existence of zirconium suboxides.
Phase Equilibrium Studies in the System Iron Oxide‐ A12O3 in Air and at 1 Atm. O2 Pressure
Authors: MUAN ARNULF , GEE C. L.
Published: June 2006

Phase equilibrium data, obtained by using the quenching technique, are presented for the system iron oxide‐A12O3 in air and at 1 atm. O2 pressure in the temperature interval 1085° to 1725°C. Stability ranges of the various phases are delineated, and approximate compositions of crystalline and liquid phases are determined. Special attention is focused on the phase Fe2O3·A12O3(ss) and its stability relationships.
Effect of Zircon and Zirconia on Thermal Expansion of Lead Borosilicate Glazes
Authors: GODEJAHN G. C. , COOK R. L.
Published: June 2006

The effect of mill additions of zircon and zirconia on the linear thermal expansion and general fired properties of a series of ten lead borosilicate glazes was determined by the interferometer and by visual inspection. Appreciable reductions in thermal expansion were observed for the glazes containing zircon
Influence of Impurities and Role of Iron Carbides in Deposition of Carbon from Carbon Monoxide
Authors: BERRY T. F. , AMES R. N. , SNOW R. B.
Published: June 2006

The dissociation of carbon monoxide in contact with iron oxide has been studied; the temperature range of the reaction has been determined; the composition and structure of the catalyst has been established; and factors inhibiting or accelerating the rate of reaction are discussed. Some related observations on used blast‐furnace fire‐clay linings are included.
Strength Properties of Sintered Alumina in Relation to Porosity and Grain Size
Authors: CUTLER IVAN B.
Published: June 2006

The strength properties of sintered alumina rods, as determined by modulus of rupture experiments, were measured for the purpose of finding the influence of grain size on strength. Sintering temperatures below and above the recrystallization temperature region were utilized in the fabrication of sintered alumina rods so that a wide variation of grain sizes could be tested. Porosity, measured as bulk density, had the largest influence on the moduli of rupture. No prominent change in strength could be observed as a result of recrystallization, but a minor decrease in strength could be attributed to an increase in void size or an increase in grain size.
Kinetics of Dehydroxylation of Kaolinite and Halloysite
Authors: BRINDLEY G. W. , NAKAHIRA M.
Published: June 2006

Previous studies of the kinetics of dehydroxylation of kaolinite and halloysite point to first‐order reactions, in approximate conformity with the Arrhenius relation. Isothermal weight‐loss measurements have shown that the rate constants are markedly dependent on factors such as specimen size, shape, and compaction. A technique has been developed for determining the reaction kinetics of infinitely thin disk‐type specimens. The reactions are then strictly first order and the Arrhenius relation is obeyed. Activation energies of 65 and 55 kcal. per mole are obtained for kaolinite and halloysite, respectively. Comparison is made between the behavior of kaolinite and halloysite on the one hand and of macrocrystalline anauxite on the other. For anauxite, nucleation and growth of nuclei produce a sigmoid‐type reaction curve, but for the fine‐grained minerals it is believed that nucleation alone is the rate‐controlling process. The dependence of the reaction rate on geometrical factors is attributed to the retention of water vapor within the powder specimen. The influence of water vapor on these reactions is discussed generally.
Plastic Deformation of Ceramic‐Oxide Single Crystals, II
Authors: WACHTMAN J. B. , MAXWELL L. H.
Published: June 2006

Sapphire single crystals exhibit the same qualitative creep properties over the temperature range 900° to 1400°C. as do comparable metal single crystals at room temperature. The creep of sapphire under constant load has four portions: (a) a period of increasing creep rate, (b) a period of decreasing creep rate, (c) a period of constant creep rate, and (d) a final period of increasing creep rate. The stress required to initiate creep falls smoothly from about 780 kg. per sq. cm. at 900°C. to about 130 kg. per sq. cm. at 1400°C. After creep is initiated, it will continue at a lower stress (the addition of chromia increases the stress required to initiate creep). The electrical resistivity of sapphire is apparently increased by plastic deformation and decreased by subsequent heating near 1800°C. Slip lines in periclase and rutile were studied and slip systems were identified.
Some Experiments in Comparing the Resistance of Enamels to Corrosion by Alkaline Solutions
Authors: KIRKPATRICK H. B. , McGANDY E. L. , RICHMOND J. C.
Published: June 2006

Experiments are described which show the effects of solution temperature, concentration, container material, and specimen position on the rate of dissolution of sheet‐steel and cast‐iron enamels by alkaline solutions. The results indicate that in designing apparatus to measure such corrosion rates the solution temperature should be controlled to at least ±0.1°C., that no glass parts of the apparatus should be exposed to the solution, and that, in the absence of stirring, consideration should be given to the positioning of the specimens. Corrosion test apparatus is described which was designed to meet these requirements.
Practical Particle‐Size Analysis of Clays: II, A Simplified Procedure
Authors: MAGUIRE S. G. , PHELPS G. W.
Published: June 2006

Particle size control testing is limited in. application because of equipment cost and complexity of operation. A re‐evaluation of published techniques indicated the merits of simplicity inherent in hydrometer procedures. Certain features, however, restricted their application. Among these were elements of time and inaccuracy of measurement in the colloidal region. The application of log probability plotting of data was investigated and was found to be feasible. The extrapolation of data determined with a hydrometer was checked by centrifuge particle‐size data and was found to be accurate enough for routine testing. By elimination of the centrifuge, an inexpensive simple technique was evolved and was checked on seventy‐five representative whiteware clays.
Effect of Thermal History on Glass Expansion Characteristics
Authors: HAGY H. E. , RITLAND H. N.
Published: June 2006

Thermal expansion data are presented for two glasses for both heating and cooling at constant rates. Heating data were taken on samples with varying thermal histories brought about by either constant‐rate cooling or by constant‐temperature stabilization before the expansion test. The fictive temperature concept is discussed in regard to these data. Expansion data are correlated with density and refractive index at room temperature for a variety of heat‐treatments.
Properties of Thorium Oxide Ceramics
Authors: CURTIS C. E. , JOHNSON J. R.
Published: June 2006

Included in this report are data concerning the strength, density, and porosity that may be expected of thoria ceramics formed by dry‐pressing and isostatic pressing and fired at 1400°, 1600°, and 1800°C. By dry‐pressing and firing at 1400°C., a density of 60% of theoretical (10.05) was obtained; at 1800°C. the density was increased to 80% of theoretical. By isostatic pressing a density of 87% of theoretical was obtained at 1800°C. A study of the densification of thoria ceramics by small additions of other inorganic materials showed the very marked effect of CaO (or CaF2) in proportions of 0.5 to 3%. In proportions of 0.5 to 1%, CaO additions produced densities of 97% of theoretical for ThO2 when fired at 1800°C. Experimental results intended to explain this phenomenon tended to substantiate the theory that it is due to formation of holes by substitutional solid solution and migration of ions in the altered structure. Thoria ceramics in the form of 12‐in. rods, 1.5 in. in diameter, and small (0.1‐in.) pellets with CaO additions were made having densities up to 97% of theoretical; evaluation of the abrasion resistance and strength is given. Porous thoria ceramics with densities of only 50 to 60% of theoretical were produced by addition of volatile material. Tests of the solubility of thoria ceramics showed that water at 250°C. had no effect. Ready dissolution was obtained with nitric acid and hydrofluoric acid as a catalyst.
Phase Equilibria at Liquidus Temperatures in the System Iron Oxide–Al2O3–SiO3 in Air Atmosphere
Authors: MUAN ARNULF
Published: June 2006

Liquidus temperatures, obtained by the quenching technique, are presented for mixtures in the system iron oxide–Al2O3–SiO2 in air atmosphere. Approximate compositions of crystalline phases in equilibrium with liquids have been determined, and paths of equilibrium crystallization are discussed briefly. Application of the phase diagram to refractories problems is indicated.
Oxidation of Manganese Ferrite
Authors: WEISZ R. S.
Published: June 2006

The oxidation of manganese ferrite (MnFe2O4) in air has been studied in the temperature range 750° to 1150°C. Between 1050° and 1150° a homogeneous oxidation takes place, resulting in a spinel phase of a defect type containing up to 10% of the manganese in the trivalent state. At 1050° and below, bixbyite (Mn2O3) and hematite (Fe2O3) are precipitated. The kinetics indicate that initially a diffusion‐limited homogeneous reaction takes place, followed by precipitation and grain growth. At lower temperatures, well‐defined Widmanstätten precipitates are formed; at higher temperatures, recrystallization alters these precipitates. The oxidation of manganese ferrite can be strongly retarded by a ceramic glaze, offering a practical method of preparing the material by air firing.
Structure of Neutron‐Irradiated Quartz and Vitreous Silica
Authors: SIMON IVAN
Published: June 2006

The structure of quartz and vitreous silica disordered by heavy irradiation (1020 neutrons per cm.2) of fast neutrons was studied by means of X‐ray diffraction and infrared spectroscopy. The results indicate that the structure of the disordered amorphous form of silica resembles closely that of vitreous silica. The average Si–O distance (1.61 a.u.) remains unchanged, but the average Si–O–Si bond angle decreases from 142° to 138°; the radial distances of the more distant neighbor atoms show a wider distribution in the disordered material. It is suggested that the disordered form of silica results from thermal effects (thermal spikes) accompanying the passage of knocked‐on atoms through the solid.
Effect of Some Lithium Compounds on Sintering of MgO
Authors: ATLAS LEON M.
Published: June 2006

The addition of 0.25% or more of certain lithium compounds, particularly the halides, facilitates the pressing and sintering of reactive forms of high‐purity magnesium oxide. Densities up to 3.46 gm. per cm.3 have been obtained at 1400°C. with reagent‐grade magnesium oxide containing 0.5% lithium chloride as an additive. The effectiveness of lithium salts as sintering catalysts for magnesium oxide depends on the original surface area and particle size of the MgO. After autoclaving at 150 lb. per sq. in. gauge for 2 hours, samples of MgO sintered at 1400°C. with 0.5%of LiCl showed a water absorption comparable to that of fused magnesium oxide. Similar samples of lithium‐treated periclase had about the same resistance to attack by a NaOH‐FeO melt as pure MgO fired at 1800° to 1850°C.