CaO-SiO2 System Research Articles

Carbon Dioxide in igneous petrogenesis: I

A number of experimental CO2 solubility data for silicate and aluminosilicate melts at a variety of P- T conditions are consistent with solution of CO2 in the melt by polymer condensation reactions such as SiO 4( 4− +CO2(v)+Si n O 3+1() (2+1) ⇌Si n+1O 3+4() (2+4)− +CO 3( )2− . For various metalsilicate systems the relative solubility of CO2 should depend markedly on the relative Gibbs free change of reaction. Experimental solubility data for the systems Li2O-SiO2, Na2O-SiO2, K2O-SiO2, CaO-SiO2, MgO-SiO2 and other aluminosilicate melts are in complete accord with predictions based on Gibbs Free energies of model polycondesation reactions. A rigorous thermodynamic treatment of published P- T-wt.% CO2 solubility data for a number of mineral and natural melts suggests that for the reaction CO2(m) ⇌ CO2(v) $$\ln X_{{\text{CO}}_{\text{2}} }^m = \ln f_{{\text{CO}}_{\text{2}} } - \frac{A}{T} - B - \frac{C}{T}(P - 1)$$ have been determined. Regression parameters are (A, B, C): andesite (3.419, 11.164, 0.408), tholeiite (14.040, 5.440,0.393), melilite (9.226, 7.860, 0.352). The solubility equations are believed to be accurate in the range 3<P<30 kbar and 1,100°<T<1,650 °C. A series of CO2 isopleth diagrams for a wide range of T and P are drawn for andesitic, tholeiitic and alkalic melts.

珪酸陰イオンを解析するための改良トリメチルシリル化法

In the application of the trimethylsilylation method by Götz and Masson for the analysis of the silicate anions, Masson et al. have shown that water is essential for the trimethylsilylation of anhydrous silicates. However, that a subreaction caused by the presence of water may affect the trimethylsilal reaction. In this work we used the improved solvents containing no water, (CH3)3SiCl 3 cm3, CH3OH 6 cm3 and (CH3)3SiOSi(CH3)3 9 cm3. Crystalline calcium silicates with well defined structures and lead silicate, which showed poor reaction efficiency in Masson’s method were analysed by these solvents. The results obtained are summarized as follows.(1) The reaction efficiency of trimethylsilylation was 100% for the glasses of PbO-SiO2 and CaO-SiO2 systems.(2) The products were obtained 100% as the derivative of Si4O1210− for the α-CaO·SiO2, 100% as the derivative of Si2O76− for the 3CaO·2SiO2 and 97% as the derivative of SiO44− for the 2CaO·SiO2.(3) For the crystalline calcium silicate (43.3 mol%SiO2) with a mixture of different anions, the products were determined to be composed of 80.5%Si2O76− and 18.6%Si4O1210− derivatives.As the result obtained was better than that by Masson’s method, the present method may be used for determining various silicate structures with high accuracy as their corresponding trimethylsilyl derivatives.

酸化性雰囲気下における溶融スラグの気化脱硫

The rates of desulphurization from liquid slag to the gas phase have been studied under an oxidizing atmosphere. A series of experiments was carried out by introducing Ar-O2 gas mixtures on to the surfaces of those liquid slags containing sulphur, such as CaO-SiO2, CaO-Al2O3 and some CaO-SiO2-MO ternary slags as well as CaF2 bearing slags.The results are as follows:(1) The desulphurization reaction of those slags by oxidizing gases is divided into a rapid rate reaction at the initial stage and a slow rate reaction at the later stage. The former should be controlled by the chemical reaction at the surface of the slags and the latter by the diffusion of sulphur in slags.(2) The rates of desulphurization of slag are proportional to the square root of partial pressure of oxygen and the rates of desuliphurization of the binary CaO-Al2O3 are higher than those of the CaO-SiO2 system. However, the rates of desulphurization for ESR slags are higher than those for CaO-Al2O3 slag. The rate constants for CaO-SiO2-MO ternary slags can be estimated from the sulphide capacity of the slags.(3) It was found that the rates of desulphurization increase in proportion to the concentration of basic oxides (CaO, MgO, MnO, FeO) but decrease as acid oxides (SiO2, Al2O3) contents are increased. Particularly, the effects of MnO and FeO are significant.

Viscosite de melanges de silicates fondus du systeme CaOSiO 2MnO

Viscosities of melts of the ternary system CaOSiO 2MnO with 0.5 to 0.35 mole% SiO 2 have been measured between the liquidus temperature and 1500°C. Results are given in function of the composition and show the effect of the silica content of the melt and of the substitution of CaO by MnO.

Rate of formation of C 3S in the system CaOSiO 2Al 2O 3Fe 2O 3MgO with addition of CaF 2

The influence of CaF 2 on the kinetics of the reaction C+C 2S → C 3S in five-component diffusion sandwiches (CaOSiO 2Al 2O 3Fe 2O 3MgO) was determined in the temperature interval 1350°C to 1500°C. With the addition of 0.5% CaF 2 to the reacting system the rate of reaction increased by a factor of 2.4 at a reaction temperature of 1350°C, and a factor of 1.2 at 1500°C. Addition of 1% CaF 2 raised the reaction rate 2.8 times at 1350°C and 1.7 times at 1500°C. The effect of CaF 2 on the rate of C 3S formation may be attributed to the fact that the C 3S primary field is much wider in the CSCaF 2 system than in the CSAF system.

A spectroscopic study of the structure of glasses in the CaO-SiO2 system

A spectroscopic study of the structure of glasses in the CaO-SiO2 system

NiOを含む溶融珪酸塩へのMgOの添加効果

The measurements of electrical conductivity for CaO-SiO2-NiO-MgO and PbO-SiO2-NiO-MgO melts have been conducted to discuss the interaction of NiO and MgO contained in silicate melts. The measurements of infrared and far-infrared absorption spectra were carried out to discuss the dissociation of NiO in the silicate.When NiO was replaced by MgO in CaO-SiO2 and PbO-SiO2 systems, the electrical conductivity tends to deviate from the additivity line to positive side. The absorption band of the molecular type (no dissociation to Ni2+ and O2−) of NiO observed in far-infrared region faded out with addition of MgO, and changed into that of dissociation type of NiO. It appears that the MgO promote the dissociation of NiO in silicate melts. The mechanism for interaction of NiO and MgO was discussed.

Poids specifiques et volumes molaires de melanges d'oxydes fondus du systeme CaOSiO 2MnO

Densities of melts of the ternary system CaOSiO 2MnO with 0.5 to 0.35 mole% SiO 2 have been measured between the liquidus temperature and 1500 °C. Molar volumes and thermal expansivity are calculated by use of the density measurements and presented as a function on the composition of the melts.

Conductivites electriques de melanges de silicates fondus du systeme CaOSiO 2MnO

Specific electrical conductivities in ternary melts of the system CaOSiO 2MnO with 55 to 26 mole% SiO 2 was measured from the liquidus temperature to 1550 °C. Knowing the molar volume of the melts, the equivalent electrical conductivities were calculated. A structural interpretation is given in view of the known theories about structure of silicate melts.

Study of the structure and crystallization properties of β-dicalcium silicate (β-C 2S) hydrate

The concentration of β-C 2S by bottle hydration at room temperature produced a similar type of calcium silicate hydrate (CSH) as that from C 3S hydrate, but containing less calcium hydroxide. However, they show differences in the course of the reaction. The morphological changes over time by hydration of β-C 2S, the properties of Ca(OH) 2 and the aqueous phase are described. The composition, the mechanism of the reaction with water, and the structure of the crystalline compounds formed in the CSH system are discussed in considerable detail. Hannawayya originally gave the name CSH(I 1) and CSH(II 2) to the calcium silicate hydrate which is produced by bottle hydration of β-C 2S hydrate. The lower and upper limits of the CaO/SiO 2 mole ratio of CSH(II 2) are 1.56 and 1.88, respectively. The present investigation deals with the system CaOSiO 2H 2O (CSH), in which equilibrium is reached through interaction between the components. The ratio of CaO/SiO 2 was determined in the solid phases under conditions of hypothetical equilibrium in solution, in which the CaO concentration was varied. The products formed are a series of compounds, whose composition varies. Their crystal structures are illustrated by scanning electron microscopy and X-ray diffraction. The uncombined calcium oxide was estimated quantitatively as calcium hydroxide, using the X-ray diffraction quantitative method. This method is clearly described. In low lime concentration, calcium silicate hydrate(I 1) (CSH(I 1)) develops flaky, crinkled, irregular crystals, some intermingled with twisted foils. In saturated and supersaturated lime solution, calcium silicate hydrate(II 2) (CSH(II 2)) develops fibrous or needle-like bundles of crystals identified by scanning electron microscopy. In a separate paper Hannawayya has made an extensive study of the product, CSH(II 2), by electron microscopy, X-ray (Guinier camera), and electron diffraction. Electron microscopy revealed that this product consisted of bundles of fibers, characteristically cigar-shaped (see, Figs. 19, 21).

Na&lt;SUB&gt;2&lt;/SUB&gt;O-SiO&lt;SUB&gt;2&lt;/SUB&gt;-MgO系およびCaO-SiO&lt;SUB&gt;2&lt;/SUB&gt;-MgO系融体の電気伝導度

The measurements on the electrical conductivity of Na2O-SiO2-MgO and CaO-SiO2-MgO melts have been conducted to find out the behavior of MgO in these systems.The electrical conductivity decreased with increasing MgO content in the Na2O-SiO2 system, but it slightly increased in the CaO-SiO2 system. The electrical conductivity gave a good linear relationship with Na atomic % in the Na2O-SiO2-MgO system and Ca+Mg atomic % in the CaO-SiO2-MgO system. Mg2+ ions contributed to the electrical conductivity in the CaO-SiO2 system to such a degree as shown by Ca2+ ions, whereas it will give no contribution in the Na2O-SiO2 system, probably due to the formation of complex anions. Compared with the viscosity data in the previous paper, the SiO2 equivalent to MgO was calculated, and the structural aspects of Mg2+ in the melt were estimated.

The structure of molten binary silicate systems CaO-SiO2 and MgO-SiO2

The structure of molten binary silicate systems CaO-SiO2 and MgO-SiO2

The structure of molten binary silicate systems CaO-SiO2 and MgO-SiO2

The structure of the molten binary CaO-SiO2 and MgO-SiO2 was investigated by means of a high temperature X-ray diffraction technique. From an analysis of the X-ray scattering intensity, the radial distribution function was evaluated from which interionic distances and coordination numbers were calculated. The following features emerge from these results: Molten silicates consist mainly of SiO4 tetrahedral units, up to 57 mol pct alkaline earth metal oxides. The number of oxygens which surround Ca and Mg at the monosilicate composition is 7 and 5 respectively. The structure of molten silicates is insensitive to temperature within the present experimental temperature range. The ionic distribution and structural changes in the molten mixture of alkaline earth silicates are also discussed.

CaO-SiO&lt;SUB&gt;2&lt;/SUB&gt;-Fe&lt;SUB&gt;2&lt;/SUB&gt;O&lt;SUB&gt;3&lt;/SUB&gt;系および，CaO-SiO&lt;SUB&gt;2&lt;/SUB&gt;-MgO系融体へのCaOの溶解機構

The mechanism of CaO dissolution into molten slag was studied by applying the hot-filament method to melt about 5 mg of slag samples on the electrically heated Pt-Rh filament.The results indicate that the molten slag migrates between the CaO crystal and a newly formed 2 CaO·SiO2 layer through the cracks as seen in CaO-SiO2 system. In the case of higher Fe2O3 content, the layers of the compounds 2 CaO·SiO2 and 3 CaO·SiO2 formed around the CaO crystal were not continuous but looked more like particles, which promoted the dissolution of CaO. In the case of higher MgO content (30% CaO-50% SiO2-20% MgO), no compound layer was observed on the CaO crystal, and Akermanite was formed around CaO in only the quenched sample.The effect of additions of chlorides (MgCl2, CaCl2, LiCl, NaCl) upon the dissolution rate of CaO was studied in the CaO-SiO2 system. The results have revealed that among the chlorides, MgCl2 is most effective in breaking the compound layer formed arround CaO, but less in extent than CaF2 addition.

CaO-SiO&lt;SUB&gt;2&lt;/SUB&gt;, Na&lt;SUB&gt;2&lt;/SUB&gt;O-SiO&lt;SUB&gt;2&lt;/SUB&gt;系におけるFeイオンの酸素配位数

In order to determine the oxygen coordination numbers of Fe ions in the melts, Mössbauer spectra of Fe ions in silicate and posphate glasses have been measured and the distributions of Fe3+ (tetr.) and Fe3+ (oct.) in CaO-SiO2 or Na2O-SiO2 systems have been calculated. The results indicate that the ratio of Fe3+ (oct.)/Fe3+ (tetr.) is varied with the basicity of glasses and Fe2O3 contents. In the glasses containing 10 mol%Fe2O3, Fe3+ (tetr.) is predominant for basic samples, and Fe3+ (oct.), on the other hand, for acidic glasses. The ratio of Fe3+ (oct.)/Fe3+ (tetr.) increases with increasing Fe2O3 content.The constitution of Fe3+-oxygen complex anions is also discussed in terms of the ratio of Fe3+ (oct.)/Fe3+ (tetr.).

X-ray diffraction studies of hydration reaction of cement components and sulfoaluminate (C 4A 3S̄) Part IA. Silicates mixed with different components

The purpose of this investigation is to determine the reaction of different cement components and sulfoaluminate in mixtures and their mutual influence on the hydration. The components used are silicates, C 3S and β-C 2S, aluminates, C 3A, C 12A 7 and CA 2, ferrites, C 4AF and C 2F, and sulfoaluminate, C 4A 3S̄. The investigation includes separate components as well as combinations of two components. These combinations include one component from each of the following groups: silicate, aluminate, ferrite and sulfate. All combinations have been made with or without addition of gypsum. All eight hundred different combinations of the components have been investigated for one day, seven days, twenty-eight days and one year. The relations between the products of hydration and the oxide compositions of the cement components in system CaO  SiO 2  Al 2O 3  Fe 2O 3 were explored. The different components were mixed at water/solid ratio of 0.5. The specimens were not protected from CO 2, consequently monocarboaluminate, C 4AC̄H 11, was formed. The hydrate phases developing during hydration have been observed qualitatively by X-ray diffraction technique. In a neat paste of C 3A, di- and tetracalcium aluminate hydrates were formed. After a while C 3AH 6 crystals appeared, according to the following scheme: ▪ High-sulfate form (ettringite) forms in hardened cement, a result of interaction of calcium sulfate with aluminates or ferrites, changing to monosulfate hydrate with time. When there are both gypsum and lime (the lime that is released from C 3S or β-C 2S during the hydration) the reactivity of C 4AF is reduced. The lime seems to stabilize the ettringite crystals somewhat. In the presence of C 3S and gypsum, the hydration of the sulfoaluminate yields a product with a greater quantity of ettringite than that from the pastes without C 3S. The new phase of gehlenite hydrate, C 2ASH 8, found in a different system, seems to be a result of the hydration of C 3S or β-C 2S in alumina saturated solution (alumina components), C 4A 3S̄.

白金電極とCaO-SiO2, CaO-SiO2-Al2O3およびCaO-Al2O3界面におけるコンデンサー成分の測定

The electrical double layer capacitance at the interface of a platinum electrode and oxide melts in the systems CaO-SiO2, CaO-SiO2-Al2O3 and CaO-Al2O3 was measured by an AC impedance method.The results obtained are as follows:(1) Capacitance-Potential curves (C-E curves) measured at various frequencies (0.2∼2.0 kHz) were similar to those for Na2O-SiO2 previously investigated.(2) There were two minima and a hump on the C-E curves extrapolated to an infinite frequency.(3) The maximum capacitance on the C-E curves increased with increasing CaO concentration and temperature.(4) The maximum on the C-E curves for CaO-Al2O3 melts was larger than those for CaO-SiO2 and CaO-SiO2-Al2O3.(5) The minimum capacitances extrapolated to infinite frequency increased with increasing CaO concentration and temperature, and the effect of temperature was more pronounced for basic slags.(6) The minimum capacitance on the anodic branch was in the vicinity of 100 mV (vs Pt), indicating adsorption of oxygen ions on the surface of the Pt electrode.(7) The span of E for adsorption or desorption of oxygen ions extended 250 to 300 mV and was independent of slag composition.

The densities and structures of melts in the system CaO-“FeO”-SiO2

The densities of melts in the systems CaO-SiO2, CaO-“FeO,” “FeO”-SiO2 and in ternary melts containing 33 and 44 mole pct SiO2 have been measured from the liquidus temperature to 1600°C. Structural interpretation of melt density and expansivity has provided information on the nature of the ions present in these systems, and, in conjunction with known thermodynamic behavior, has indicated the natures of the interactions occurring among these ions. The influence of temperature, silica content andCaO/FeO ratio on the structures of ternary iron-calcium silicates is discussed.

Ionic Conductivity in Calcium Silicate Glasses

Glasses in the system CaO–SiO2 were prepared with the composition varying from 40 to 55 mole % CaO. The Na2O impurity content ranged from 0.01 to 1.30 mole %. The electrical resistivity was insensitive to the Na2O content but decreased with increasing CaO concentration. The activation energy for conduction ranged from 33.54 to 31.23 kcal/mole as the CaO concentration increased. The conduction mechanism was considered in terms of three arbitrary parameters: (1) equivalent oxygen packing density, (2) ionic radius, and (3) ion‐oxygen attraction.

A New Calcium Silicosulphate

A COMPREHENSIVE investigation is in progress of high-temperature phase equilibria in the system CaO—SiO2—SO3 which is important in the chemistry of cements. A new compound has been located of molar composition at present best represented as (2CaO.SiO2)2.CaSO4. This compound has been prepared from calcium carbonate (99.9 per cent pure), crushed quartz (99.95 per cent pure) and AnalaR CaSO42H2O by ignition for 150 h at 1,150° C in platinum boats in a platinum-rhodium resistance furnace. For successful preparation the mixture has to be finely ground to pass a 300-mesh sieve in between periods of heating. The X-ray diffraction pattern of the new compound first became discernible after about 2 h of heating. On continued heating, the X-ray diffraction patterns of the reactants and of dicalcium silicate became progressively weaker until, after 150 h, they reached intensity-levels representative of trace quantities.