Showing papers in "Journal of the American Ceramic Society in 1961"
TL;DR: An idealized experimental study of particle packing was made as mentioned in this paper, where spherical metal shot of several discrete, narrow size ranges was efficiently packed in glass containers by mechanical vibration, and the significance and utility of this work to the ceramic and other industries was discussed.
Abstract: An idealized experimental study of particle packing was made. Spherical metal shot of several discrete, narrow size ranges was efficiently packed in glass containers by mechanical vibration. Packing arrangements and the dynamic process of packing were studied visually. One-size spheres packed in an orthorhombic arrangement with a density 62.5% of theoretical density. Forming of high-density multicomponent packings was shown to require at least a sevenfold difference between sphere sizes of the individual components. A quaternary packing with a density 95.1% of theoretical density was formed from spheres with diameter ratios 1:7:38:316 and volume compositions 6.1:10.2:23.0:60.7%, respectively. Such packings could be poured from their glass containers, thus proving that effective mechanical packing is simply an efficient arrangement of spheres of prescribed sizes and proportions. The significance and utility of this work to the ceramic and other industries is discussed.
869 citations
545 citations
491 citations
TL;DR: Inert marker experiments have shown that the solid-state reactions forming MgAl2O4 and MgFe3+, and A13+ ions through the relatively rigid oxygen lattice of the spinel or ferrite as mentioned in this paper.
Abstract: Inert marker experiments have shown that the solid-state reactions forming MgAl2O4 and MgFe2O4 occur by counterdiffusion of the Mg2+, Fe3+, and A13+ ions through the relatively rigid oxygen lattice of the spinel or ferrite. It is suggested that earlier claims that ZnAl2O4 forms by diffusion of Zn2+ and O2- ions were probably due to a splitting of the markers, leaving some marker on the specimen surface. Pores in one component of a reacting couple are shown to serve as inert markers. The formation of those materials, e.g., ferrites and stannates, which dissolve marker materials can now be studied.
255 citations
TL;DR: The grain size of TiO2 heated in H2 has been shown to be larger than that of the same grain in O2, in air, in argon, and in vacuum as discussed by the authors.
Abstract: Additions of NiO, CoO, MnO2, Fe2O3, and CuO promote the anatase-rutile transformation and grain growth of TiO2. Additions of Na2O and WO3 retard the transformation and have no effect on the grain growth. The addition of MoO3 strongly promotes the grain growth but has only a slight effect on the phase transformation. Both the grain growth and transformation are promoted slightly by Cr2O3. The transformation is significantly affected by the method of preparing TiO2. The grain size of TiO2 heated in H2 exceeds that of TiO2 heated in O2, in air, in argon, and in vacuum. The rate of transformation decreases with an increase in the partial pressure of oxygen of the atmosphere.
164 citations
TL;DR: In addition to the well-known zinc orthotitanate (Zn2TiO4), the study of solid-state reactions in the system ZnO-TiO2 disclosed a previously unrecognized compound as discussed by the authors.
Abstract: In addition to the well-known zinc orthotitanate (Zn2TiO4) and zinc metatitanate (ZnTiO3), the study of solid-state reactions in the system ZnO-TiO2 disclosed a previously unrecognized compound, Zn2Ti3O8. This compound was obtained when sulfate-containing hydrous titanium oxide of anatase structure was reacted with ZnO at 700° to 900° C. It crystallized in a defect spinel structure with eight Zn2+ ions occupying the tetrahedral positions and twelve Ti4+ ions distributed in sixteen octahedral positions (a0= 8.395 ± 0.002 a.u.). Crystallographic data are given for zinc orthotitanate and metatitanate.
Formation of the latter compound appeared to be favored by rutile TiO2 sources and those readily convertible to rutile under the reaction conditions.
163 citations
TL;DR: In this paper, a non-mathematical elucidation of the physical phenomena underlying radiant heat transfer in glass is presented, where conditions at the boundaries of transparent bodies and applications to unsteady-state processes are discussed.
Abstract: This review is aimed at a nonmathematical elucidation of the physical phenomena underlying radiant heat transfer in glass In transparent materials, unlike the more familiar opaque materials, the emission and absorption of radiation are bulk, rather than surface, phenomena Interaction of the simultaneous emission and absorption of radiation throughout the volume leads to a dependence of the emissivity of transparent bodies on their thickness The interaction also leads to a mechanism of radiative heat transfer in the interior of transparent materials entailing not the familiar radiation through them but internal radiant exchanges between nearby layers The analogy of this mechanism with thermal conduction has led to the definition of an equivalent ‘radiative conductivity” The origin and limitations of this concept are briefly discussed, together with conditions at the boundaries of transparent bodies and applications to unsteady-state processes
127 citations
TL;DR: In this article, the formation of Cr3O8, Cr2O5, CrO2, and CrO3 by the decomposition of anhydrous chromium oxides under high oxygen pressure and their physical and chemical properties are presented.
Abstract: The formation of Cr3O8, Cr2O5, CrO2, and Cr2O3 by the decomposition of anhydrous CrO3 under a high oxygen pressure and their physical and chemical properties are presented. The crystal structure of CrO2 is a rutile type and its lattice constants do not vary with the ratio O/Cr. The specific gravity of CrO2 decreases with an increase in the ratio O/Cr. This is explained by assuming that the crystal structure of CrO2 contains an excess of Cr ions at interstitial sites. This crystal model is supported by the low electrical resistivity of CrO2. An electron microscopic examination showed an abnormal grain growth of CrO2 during the decomposition of Cr2O5 to CrO2. The activation energies of the decomposition of Cr2O5 and CrO2 to Cr2O3 in air are 61.7 and 48.2 kcal. per mole, respectively. The pressure-temperature diagram of various chromium oxides has been determined. From the pressure-temperature curve of CrO2-Cr2O3 the heat of decomposition is found to be 26.3 kcal. per mole.
117 citations
TL;DR: In this article, the common oxides of lead were examined at pressures of 0 to 60,000 atmospheres and temperatures of 100° to 600° C. The pressure-temperature curve for the litharge-massicot transition was measured, giving a ΔH of transition of 57 cal. per mole.
Abstract: The common oxides of lead, PbO, PbO2, and Pb3O4, were examined at pressures of 0 to 60,000 atmospheres and temperatures of 100° to 600° C. The pressure-temperature curve for the litharge-massicot transition was measured, giving a ΔH of transition of 57 cal. per mole. Unusual meta-stability and inversion characteristics of the massicot phase were examined in detail. PbO2 (rutile) transformed at pressures in excess of 13,000 atmospheres at 300°C. to an ortho-rhombic form. The univariant equilibrium curve for the transition gave a ΔH of 11 cal. per mole. Pb3O4 underwent a disproportionation reaction yielding PbO and “Pb2O3.” The equilibrium curve for this reaction was measured, and ΔH was determined to be 4500 cal. per mole.
110 citations
TL;DR: In this article, the diffusion rate of silicon carbide was studied at different partial pressures of water vapor and showed that the diffusing species appeared to be the same in the presence of partial pressure of water vapour and oxygen.
Abstract: The rate of oxidation of silicon carbide was studied at different partial pressures of water vapor. The diffusion-rate constant was found to vary with the logarithm of the partial pressure of water vapor according to the theory of thin-film oxidation as proposed by Engell and Hauffe. The products of oxidation were cristobalite and tridymite, depending on the temperature. The diffusing species appeared to be the same in the presence of partial pressures of water vapor and in the presence of partial pressures of oxygen.
105 citations
TL;DR: 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 as discussed by the authors.
Abstract: 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.
TL;DR: In this paper, anomalous resistivity-temperature characteristics found in semiconducting barium titanates were studied in relation to their composition, and the resistivity and impedance characteristics and the crystal structures were investigated for different compositions in the systems.
Abstract: The anomalous resistivity-temperature characteristics found in semiconducting barium titanates were studied in relation to their composition. The resistivity and impedance characteristics and the crystal structures were investigated for different compositions in the systems (Ba, -Sr) (Ti, Sn)O3, (Ba, Ca, Sr)TiO3) (Ba, Pb)TiO3, Ba-(Ti, Zr)O3, and Ba(Ti, Si)O3 doped with 0.1 mole % of Ce and also in the system (Ba, Mg, Ce) TiO3. Bodies whose compositions were quite different from BaTiO3 could not be semiconducting. The resistivity anomaly in each semiconducting body showed a good correlation with the crystal transition.
TL;DR: The effect of rare earth oxides on the d-c resistivity of sintered barium titanate was investigated in this paper, where the rare earths samarium, gadolinium, and holmium were introduced singly into the titanate, and the resistivity was measured as a function of temperature from -170 deg to +330 deg C.
Abstract: The effect of additions of 0.0015 to 0.0030 mole fraction of rare earth oxides on the d-c resistivity of sintered barium titanate was investigated. The substitution may be represented by (X/sub 2/O/sub 3/)M (BaTiO/sub 3/)/sub 1-M/, where X is the rare earth. The rare earths samarium, gadolinium, and holmium were introduced singly into the titanate, and the resistivity was measured as a function of temperature from -170 deg to +330 deg C. An anomalous increase near the tetragonal -- cubic transition temperature at 120 deg C occurred which in some cases amounted to an increase in the resistivity of 4000 times the value in the tetragonal phase. The thermoelectric power of the material changed sign at the Curie temperature. The tetragonal phase exhibited n-type behavior whereas the cubic phase was p-type. The rhombohedral and orthorhombic phases exhibited conduction activation energies of the order of 0.2 ev whereas that in the tetragonal phase was approximately 0.1 ev. (auth)
TL;DR: Theoretical estimations of the sintering rate are in reasonable agreement with experimental measurements as discussed by the authors, which is consistent with the observed microstructure changes in several systems and the rate of densification of magnesium oxide, titanium carbide, and tungsten carbide.
Abstract: Observations of microstructure changes in several systems and the rate of densification during sintering of magnesium oxide, titanium carbide, and tungsten carbide in the presence of a liquid phase indicate that the densification rate is controlled by diffusion through a liquid film between particles. Dependence of the sintering rate on time, particle size, and temperature are in agreement with predictions. Theoretical estimations of the sintering rate are in reasonable agreement with experimental measurements.
TL;DR: In this paper, the phase equilibrium diagram for the system La2O3-b2o3 has been determined experimentally and a method for estimating immiscibility in the system is demonstrated, which requires experimentally only the determination of the index of refraction of the modifier-rich liquid.
Abstract: The phase equilibrium diagram for the system La2O3-B2O3 has been determined experimentally. The compounds La2O3-3B2O3and La2O3-B2O3 melt congruently at 1141°± 5°C. and 1660°± 15°C, respectively. At 1488°± 5°C, La2O3-B2O3 inverts from the aragonite-type structure to a high-temperature form. Trilanthanum borate, 3La2O3 B2O3, melts incongruently at 1386°± 5°C. to give liquid and La2O3. No solid solutions exist in the system. A region of liquid immiscibility exists in the system and extends at 1136°± 5°C. from almost pure B2O3 to 21.5 mole % La2O3. The experimental value for the extent of immiscibility agrees with that calculated from theoretical considerations. A second method for estimating immiscibility in the system is demonstrated, which requires experimentally only the determination of the index of refraction of the modifier-rich liquid. Principles governing immiscibility are discussed.
TL;DR: In this article, the relations between the structure, crystal chemistry, chemical bonds involved, and the infrared spectra of layer-structure silicates established on the basis of recent experiments are discussed and summarized.
Abstract: The relations between the structure, crystal chemistry, chemical bonds involved, and the infrared spectra of layer-structure silicates established on the basis of recent experiments are discussed and summarized.
TL;DR: In this article, a study of the growth of barium ferrite single crystals from a sodium carbonate flux was made, and the effects of variations in batch composition, heating cycle, and seeding have been studied from the point of view of crystal yield and quality.
Abstract: 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.
TL;DR: In this article, the phase properties of the spinel phase of Magnesioferrite were investigated and the phase was shown to decompose at 1713°± 5°C. to a solid solution phase and liquid, under equilibrium conditions in air.
Abstract: The quenching technique has been used to investigate phase relations in the liquidus temperature region of a part of the system magnesium oxide-iron oxide. The study concerns primarily the nature of the melting behavior of the spinel phase magnesioferrite, “MgO-Fe2O3.” This phase is shown to decompose at 1713°± 5°C. to a magnesiowustite solid solution phase and liquid, under equilibrium conditions in air.
TL;DR: In this article, the authors describe pyrolytic graphite as a vapor-deposited form of carbon which is characterized by strong anisotropic properties, which is caused by the tendency of individual crystallites to align themselves in such a way that their c axes are perpendicular to the surface of deposition.
Abstract: Pyrolytic graphite is a vapor-deposited form of carbon which is characterized by strong anisotropic properties. The anisotropy is caused by the tendency of the individual crystallites to align themselves in such a way that their c axes are perpendicular to the surface of deposition. The Individual crystallites are composed of parallel graphitic layers which are randomly oriented with respect to the c axis. The ultimate strength of pyrolytic graphite in tension, bending, and compression has been found to increase considerably with increasing test temperatures. Other properties such as thermal conductivity and electrical resistivity give extremely high and low conduction parallel and perpendicular to the basal planes, respectively, in addition to varying considerably with increasing test temperatures. Properties are also influenced by the as-deposited microstructure and by the amount of graphitization to which the material has been subjected. The properties and possible uses of this unique material are presented, discussed, and compared with the properties of other high-temperature materials.
TL;DR: In this article, the stability regions of the α-oxides (FemTi2-mO3), of the spinels, (FenTi3-nO4), and of the orthorhombic oxides (fepTi3p O5) were determined.
Abstract: The 1200°C. isotherm in the system Fe-Ti-O has been studied by equilibrating mixtures of iron oxide (Fe2O3) and titanium oxide (TiO2) with atmospheres of controlled oxygen partial pressure. These atmospheresmnsisted of CO2, air, oxygen, mixtures of CO2 and H2, and mixtures of CO2 and CO. The resulting oxide mixtures were examined at room temperature by chemical analysis and by X-ray diffraction. The stability regions of the α-oxides (FemTi2-mO3), of the spinels, (FenTi3-nO4), and of the orthorhombic oxides (FepTi3-p O5)were determined. Some nonstoichiometry occurs in the spinels and in the α-oxides. The oxygen partial pressures at which spinel is reduced to (iron +α-oxides) and at which α-oxide (ilmenite) is reduced to (iron + orthorhombic oxide) were determined as 2.1 × 10−13 and 9.3 × 10−14atm., respectively. The orthorhombic solid solution series extends over the whole range of oxygen partial pressures studied.
TL;DR: The conditions under which tridymite becomes a stable phase have been investigated in this paper, and the results showed that the formation of trithymite can be strictly a solid state process.
Abstract: The conditions under which tridymite becomes a stable phase have been reinvestigated. When quartz was heated with 2% alkali oxide, tridymite formed directly at 872° to 898°C. with Na2O, at 883° to 902°C. with K2O, and above 1005°C. with Li2O. Cristobalite occurred as an intermediate phase above 893°C. with Li2O, above 898°C. with Na2O, and above 902°C. with K2O. When quartz plus sodium chloride was heated in vacuum, tridymite did not form but cristobalite started to appear at 1050°C. The results showed that the formation of tridymite can be strictly a solid-state process. New schematic tentative diagrams for the high-silica region of binary systems are suggested. Quartz and cristobalite are regarded as the only stable crystalline phases of pure silica. Tridymite is pictured as a binary incongruently melting phase.
TL;DR: In this article, the effect of compaction on the physical properties of fibers is discussed and the mechanism of this phenomenon is described briefly, but the effect is not discussed in detail.
Abstract: Glass fibers as commercially produced have physical and mechanical properties which differ from those of the massive form of the same glass. When these fibers are subjected to subsequent heat-treatments, the values of the measured properties tend to return to those of the massive glass. This phenomenon is called compaction because in the process density increases. The effect of compaction on the physical properties of fibers is discussed and the mechanism of this phenomenon is described briefly.
TL;DR: In a hydrogen atmosphere, MgO was vaporized by heating periclase in the range 1500° to 1900° C, and the vapor products diffused into Al2O3 (sapphire) to form a uniform outer layer of spinel on all surfaces as discussed by the authors.
Abstract: In a hydrogen atmosphere, MgO was vaporized by heating MgO (periclase) in the range 1500° to 1900° C, and the vapor products diffused into Al2O3 (sapphire) to form a uniform outer layer of spinel on all surfaces. At 1900°C. a spinel layer 48 mils thick could be obtained in 16 hours. The rates of spinel formation were determined and the activation energy was calculated to be about 100 kcal. per mole. In the spinel layer, the lattice constant, Vickers hardness, and the refractive index varied from the outer surface to the inner boundary in a fairly uniform manner, indicating a continuous change in composition from 1MgO: 1Al2O3 to 1MgO: 2–3Al2O3. In conversion to spinel a volume increase of 47% over that of the original sapphire took place. Transparent clear shapes of spinel such as disks and rods were obtained from clear sapphire and from translucent polycrystalline alumina. Clear rods of spinel with polished ends acted as thin lenses, round rods as convex lenses, and flat rods as planocylindrical lenses owing to the increase in refractive index from the outer surface to the inner central portion. Objects made of opaque polycrystalline alumina were also converted to spinel. The MgO periclase blocks were etched in the hydrogen atmosphere, and the vapor products of Al2O3 entered the MgO to form tiny spinel droplets in an opalescent border. In an oxidizing atmosphere, spinel was formed only on the surface of the sapphire directly in contact with periclase, in the range 1500° to 1900°C.
TL;DR: In this article, a phase diagram was constructed up to 1100°C and 90,000 atmospheres, the probable melting curve being calculated by the use of the Simon melting equation.
Abstract: Crystalline B2O3 was readily obtained from the glassy phase at high pressures and temperatures. Single crystals 0.3 mm. in dimension of both α-B2O2 (ordinary hexagonal) and β-B2O3 (dense monoclinic) were prepared. The difference in the density of the two forms was about 20%. Crystals of β-B2O3 were only slowly attacked by H2O and dilute HF. At atmospheric pressure, transitions between the α-, β-, and liquid phases were extremely sluggish. A tentative phase diagram was constructed up to 1100°C. and 90,000 atmospheres, the probable melting curve being calculated by the use of the Simon melting equation.
TL;DR: In this paper, the transformation of quartz to cristobalite was studied in the temperature range 1400° to 1650° C. The process was found to be a consecutive reaction involving an intermediate transition phase.
Abstract: The transformation of quartz to cristobalite was studied in the temperature range 1400° to 1650° C. The process which was believed to be a direct one was found to be a consecutive reaction involving an intermediate transition phase. Both Madagascar and Brazilian quartz were used to study the transformation reaction. The reaction rate was found to be much faster for the Madagascar quartz than for the Brazilian quartz, although no difference in their impurity content was found in the spectrographic analysis. An approximate consecutive reaction kinetics was applied and the deviation of the experimentally observed values of the transition phase at a particular temperature from that of the mathematical prediction was noted and is discussed.
TL;DR: The conversion of boehmite to transition aluminas and to alpha (corundum) was studied in this paper, where the conversion rate was strongly dependent on the temperature of the transition.
Abstract: The conversion of boehmite to transition aluminas and to alpha (corundum) was studied with (a)fibrillar colloidal boehmite, about 50 a.u. in diameter, (b)finely divided boehmite in the form of thin elongated platelets, and (c)macroscopic boehmite crystals. In the range 500o to 700o C., (a)was converted to fibrillar gamma, essentially unchanged in size or shape, (b)was dehydrated to gamma, but the platelets appeared to be partly cracked longitudinally about every 70 a.u., and (c)was similarly cracked into much smaller crystallites of gamma. At about 1000oC., (a)yielded only rodlike theta alumina, whereas (b)and (c)appeared to give a mixture of theta and delta aluminas, characterized by round holes or pores developed from the cracks. In the range 1000o to 1100oC., all the aluminas were converted to alpha, at a rate which was strongly dependent on temperature. The conversion of (a)and (b) to alpha could be followed by subsequent examination with the electron microscope. The alpha crystals, once nucleated, apparently grew rapidly to 0.5 or 1.0 μ in size, since there was no evidence of smaller alpha crystals. The smaller alpha crystals appeared to grow while embedded in a glassy matrix which must have been amorphous alumina. This phase acted as a bridge between the diminishing theta particles and the growing alpha crystals and may have consisted of the alumina which was in the process of being transported.
TL;DR: In this paper, temperature and ternary composition for coexisting liquid and crystalline phases on the air isobar in the system Fe2O3-Fe3O4-YFeO3 with particular regard to the stability range and compositional limits of yttrium iron garnet were determined by conventional quenching techniques combined with measurements of loss in weight at the reaction temperature.
Abstract: Measurements were made of temperature and ternary composition for coexisting liquid and crystalline phases on the air isobar in the system Fe2O3-Fe3O4-YFeO3 with particular regard to the stability range and compositional limits of yttrium iron garnet. Phase equilibrium relations were determined by conventional quenching techniques combined with measurements of loss in weight at the reaction temperature to locate true ternary compositions. The intersection of the air isobar with the ternary univariant boundary curve for coexisting magnetite, garnet, and liquid phases results in a eutectic-type situation at the composition Y0.27Fe1.73 O2.87 and 1469°± 2°C. A similar intersection of the isobar with the boundary curve for coexisting garnet, orthoferrite, and liquid phases gives rise to a peritectic-type reaction at 1555° 3°C. and Y0.44Fe1.56 O2.89 The yttrium iron garnet crystallizing from liquids within these temperature and composition limits contains up to 0.5 mole % iron oxide in excess of the stoichiometric formula in terms of the starting composition 37.5 mole % Y2O3, 62.5 mole % Fe2O3. At 1470° C. the garnet phase in equilibrium with oxide liquid contains 2 mole % FeO in solid solution. The small solubility of excess of iron oxide and partial reduction of the garnet phase in air are unavoidable during equilibrium growth from the melt.
TL;DR: The strength and static fatigue behavior of abraded glass specimens tested in various surrounding media have been studied in this paper, showing that liquid water is the most effective agent for promoting a high rate of static fatigue and very dry air with a small concentration of water vapor is least effective.
Abstract: The strength and static fatigue behavior of abraded glass specimens tested in various surrounding media have been studied. The test media included distilled water, nitrogen atmospheres of varying humidity, methyl and isopropyl alcohol and mixtures of these with distilled water, and various acidic and basic solutions. For intermediate durations of load the strength values in atmospheres of 0.5 and 43% relative humidity were 45 and 20% greater, respectively, than in distilled water. The value of t0.5, the characteristic duration for static fatigue, under these three test conditions was 3500, 200, and 8 seconds, respectively, for the particular grit-blast abrasion studied, indicating that liquid water is the most effective agent for promoting a high rate of static fatigue and very dry air with a small concentration of water vapor is least effective. In reagent-grade methyl or isopropyl alcohol (0.01 to 0.05% H2O) the strength at an intermediate load duration of 10 seconds was about 40% greater than in distilled water and the slope of the static fatigue curve differed somewhat from that obtained for tests in water. With the addition of water to the alcohol solutions the fatigue curve became parallel to that for water, and as the water content was increased, the curves shifted toward the water curve. For tests in acidic and basic solutions the strength at an intermediate load duration was independent of pH over the range pH 1 to 13. For more acidic solutions the strength was slightly less and for more basic solutions slightly greater than in this range. The results are discussed in terms of possible mechanisms for static fatigue. It is concluded that the static fatigue of abraded glass results from changes in the shape or size of surface abrasion cracks under the combined action of stress and the surrounding medium. In general, water or water vapor is the primary agent in promoting fatigue, and, unlike the usual chemical attack, the interaction appears to involve primarily the neutral water molecule and the SiO2 network of the glass. The presence of other ions or molecules is relatively unimportant except as it may serve to reduce the concentration of water and its availability to the tip of the abrasion crack.
TL;DR: In this article, solidus equilibrium relations in a portion of the system Li 2O-Fe2O3-Al 2O3 in the temperature range 500° to 1400°C. have been determined near po2= 0.21.
Abstract: Subsolidus equilibrium relations in a portion of the system Li2O-Fe2O3-Al2O3 in the temperature range 500° to 1400°C. have been determined near po2= 0.21. Of particular interest in this system is the LiFe5O8-LiAl5O8 join, which shows complete solid solution above 1180°C. Below this temperature the solid solution exsolves into two spinel phases. At 600°C. approximately 15 mole % of each compound is soluble in the other. The high-temperature solid solution and the low-temperature exsolution dome extend into the ternary system from the 1:5 join. There is no appreciable crystalline solubility of LiFeO2 or of α-Fe2O3 in LiFe5O8. An attempt to confirm HFe5O8 as the correct formulation of the magnetic ferric oxide “γ-Fe2O3” was inconclusive, but in the absence of positive evidence, the retention of γ-Fe2O3 is recommended. All the metallic oxides of the Group IV elements increase the temperature of the monotropic conversion of -γ-Fe2O3 to α-Fe2O3. Silica and thoria have a greater effect on this conversion than does titania or zirconia.