Masanaga Kunugi

Elastic properties of GeSe glass under pressure

Abstract Elastic moduli and their pressure derivatives of GeSe glass of Ge content up to 30 at% have been determined at 15°C and 1 kbar by ultrasonic interferometry. Sound wave velocities νl and νt, and elastic moduli of this system, increased with Ge content and with pressure. The pressure derivatives K′0 and G′0 are in the range: K′0 = 7.9 ± 0.3 and G′0 = 2.2 ± 0.3. From this measurement it was concluded that GeSe glass is elastically normal. Elastic moduli of GeSe2 glass were estimated from the present data, and the K0 value was compared with those of silica-type glasses, e.g. SiO2, GeO2 and GeS2, based on the 4 3 power law. Elastic normality of GeSe2 glass was also elucidated from the estimated values of K′0 = 8 and G′0 = 2.2 for this glass, despite the structural similarity in Ge coordination between GeO2 and GeSe2 glasses.

Elastic properties of Se and As2Se3 glasses under pressure and temperature

Abstract The sound velocities and their pressure and temperature variations of Se and As 2 Se 3 glasses have been determined by means of a pulse superpositions method, and other elastic constants and their pressure and temperature derivatives were calculated from these data. The bulk modulus was found to be 94·6 kbar for Se glass and 143·7 kbar As 2 Se 3 glass, both of which are higher than the values calculated from the previous compression data. No anomaly was observed in any of the pressure and temperature dependence of elastic behavior of these glassses. Furthermore, the comparison of the pressure and temperature derivatives of the bulk modulus indicates that the thermodynamic self-consistency is satisfied on these materials. The bulk moduli of these glasses and crystalline As and Se were used to obtain an empirical bulk modulus-volume relationship for compounds in the As−Se system. The acoustic Gruneisen parameter was calculated and compared with the thermal Gruneisen parameter.

Temperature and pressure dependence of the elastic property of GeS2 glass

Abstract The sound velocities in GeS 2 glass have been measured by means of ultrasonic interferometry as a function of temperature or pressure up to 1.8 kbar. The bulk modulus K s = 117.6 kbar and shear modulus G = 60.60 kbar were obtained for GeS 2 glass at 15°C and 1 atm. The temperature derivatives of both sound velocities and elastic moduli are negative : ( ∂ν 1 ∂T ) p = −1.54 × 10 −4 km sec °C, ( ∂ν 1 ∂T ) p = −1.27× 10 −4 km sec °C and ( ∂K s ∂T ) p = −1.27 × 10 −2 kbar °C , ( ∂G ∂T ) p = −1.23 × 10 −2 kbar/°C, ( ∂Y ∂T ) p = −2.93 × 10 −2 their pressure derivatives are positive: ( ∂ν 1 ∂P ) T = 4.43× 10 −2 km/kbar, ( ∂ν 1 ∂P ) T = 0.633 × 10 −2 km kbar and (∂K s∂P0 ) T =6.81, ( ∂G ∂P) T = 1.03, (∂Y∂T T = 3.57. The Gruneisen parameter, γ th = 0.298, and the second Gruneisen parameter, δ s = 3.27, have also been calculated from these data. The elastic behavior of GeS 2 glass has proved to be normal despite the structural similarity among the tetrahedrally coordinated SiO 2 , GeO 2 and GeS 2 glasses.

Optical Spectra of Chromium in Mixed Alkali Silicate Glasses

As an approach to the mixed alkali effect in glass, the optical absorption spectra of Cr3+ were determined in mixed alkali silicate glasses. The values of the crystal field strength Dq and the Racah parameters B and C for the glasses were calculated from the observed band positions. The crystal field strength Dq is plotted in Fig. 1 against alkali concentration ratio, R1/(R1+R2) where (R1, R2)=(Li, Na), (Na, K) or (K, Li). The curves in Fig. 1 show that Dq deviates downwards from linearity predicted by combining the values for the end members, i.e., there is a minimum for Dq. The behavior in the glasses shown by curves in Fig. 1 may be interpreted based on the presence of mixed alkali effect.

Reduction of Aluminium Titanate

The reduction of aluminium titanate (Al2TiO5) heated at various temperature in the range of 1000∼1500°C in the reducing atmosphere containing hydrogene has been studied by the methods of X-ray analysis, differential thermal analysis and thermogravimetric analysis.The aluminium titanate was prepared by heating Al2O3-TiO2 compacts in air at 1550°C for three hours.As shown in Fig. 3, the X-ray patterns of Al2TiO5 heated at different temperatures under the reducing atmosphere containing hydrogene have shown an observable shift in the (33.0) line and the evidence of α-Al2O3.From the relation between the d value or density of the product formed by the reduction of Al2TiO5 and the extent x of solid solution, it is seen that the product is a solid solution such as {(1-x)Al2O3+xTi2O3}·TiO2.

Magnetic Properties of Silicate Glasses Containing Iron

The variation with temperature of the magnetic susceptibility of sodium silicate glasses containing various amount (0.5∼17.0%) of iron oxide has been studied over the temperature range -180 to 400°C. As a complementary study, the optical transmission properties of the glasses used in the magnetic work were measured in the visible and near infra-red regions of the spectrum.The mass magnetic susceptibility χb of the parent glass was found to be temperature invariant and negative. The glasses containing the iron oxide additions (0.5∼2.5%) showed a relationship between the value χg-χb and the absolute temperature T of the form χg-χb=C/T, where χg is the mass magnetic susceptibility of the glass and C the constant. Three forms of iron are present in the glasses, namely, as fine particles of ferric oxide, Fe3+ and Fe2+ ions. The proportion of iron present as fine particle of ferric oxide seems to increase with the increase of total iron concentration.

Some Experimental Formulae on the Flow of Molten Glass in a Tank Furnace

From the results of model experiment convection current of molten glass the authors tried to analyse the flow mathematically and to introduce the experimetl formula on the convection current.The temperature of glass in the vertical section at the hot spot ts, the temperature of glass in the descending flow layer near the side wall tw, the thickness of the layer δ, the depth of neutral point Zn, the average velocity of of current at the layer upper than the neutral point vu were formulated as the equation (3), (6), (18) and (14) respectively.

Studies on the Model Experiment of the Flow of Molten Glass in a Tank Furnace

Many researchers have attempted various model experiments as a method to study the flow patterns or the characteristics of the convection current of molten glass in a tank furnace, as well as the theoretical considerations of the law of similarity. However, the adaptation of the similarity criteria may still be open to criticism.Standing on the experiences obtained from the previous model experiments the authors intend in this paper to scrutinize the law of similarity and to get the practical and convenient method for determining the experimental conditions, with which the law may be satisfied as much as posible. In the last part of this paper some results of model experiments are indicated and the applicability and its limitations are discussed.Considering the conditions which make the three equations governing the behavor of liquid in scale model, i.e., Navier-Stokes equation, the equation of continuity and the equation of energy, similar to those of the actual tank, the similarity criteria being Pr, Gr and Re for the pull current were derived. Furthermore, the authors pointed out that some quantites in these formulae for the model should have the proportional relations to those of the actual tank and the other such as pressure, temperature and time have the linier relations, so these quantities must be selected initially to satisfy the demands.As a model liquid glycerin was used and Gr and Pr numbers for this liquid were determined for vaious concentrations, scales of model and the maximum and minimum temperatures in model. The results are summerized in Fig. 6 which shows the experimental conditions to satisfy the similarity criteria. The maximum and minimum temperatures used above were so determined that the ratio of the viscosities of glycerin at these temperatures in model is equal to that of glass in actual tank. Consequently it is found that, for instance, using 88% glycerin as the working liquid in the 1/30 scale model the applicable temperatures of the liquid are 18.5°C and 56°C against 1200°C and 1500°C in the proto type, and for the 1/50 scale model using 82% glycerin they are 14°C and 57°C.On the experimental technique it is convenient that the temperature distribution of liquid in model is made similar to that of actual tank by the method of adjusting the heating and cooling conditions.From the observations of flow patterns in our experiments it is believed that for the most part of tank the model has a posibility to represent the behavor of molten glass in actual tank fairly well.

Fundamental Studies on the Gas Flow Problems in Furnaces by Model Techniques Using Liquids

Flame length, flow patterns, and the degree of mixing of Jets in furnaces were studied by liquid model experimants.The dilute solutions of caustic soda, and of hydrochrolic acid were used to stand for, respectively, fuel gas and air in the model. The former was coloured by phenolphthalein to visualize the end point of the neutralizing reaction between the solutions supplied in two separate streams. The point at which the colour of the caustic soda solution just vanishes indicates the position of the tip, and thus the length of flame. In Fig. 2 and 3 are plotted the flame lengths under various excess air rates. The curves make it clear that the flame lengths decreases with an increasing excess air rate. The flame length was also affected by the relative port velocity as shown in Fig. 5. Some examples of liquid model flames in a scale model were shown in Fig. 6.A series of experiments was carried out to observe the flow patterns from the photographic records of the tracks of tracer particles moving in the illuminated area of the water jets in a box. When there is a difference between the velocities of two jets one having a lower velocity is drawn into the other, so that, after a little while, both flow as a single unit as it is seen in Fig. 7 b. The intensity of turbulence in the jets was evaluated from the records of the tracks described by the tracers.

Fundamental Studies on the Characteristics of Convection Current of Molten Glass by Model Techniques

All phenomena occurring in a glass tank furnace, i.e., melting the batch, refining and conditioning the molten glass, and other chemical and physical processes are connected inseparably with the convection current of molten glass. It may, therefore, be said that the effort to understand these complicated processes cannot be successful without learning the fundamental characteristics or trends of convection current.From this view point the authors carried out some series of model experiments using glycerin in place of the molten glass. In a box having a simple rectangular shape the glycerin was heated uniformly from above and cooled through side and bottom walls of the box. Temperature distributions in the fluid were measured with Cu-Constantan thermocopules whose junctions were fixed at twenty points in the vessel, and the flow patterns were observed from the photographic records of the tracks of tracer particles moving in the illuminated area of the liquid. Various factors, for example, heat input from the top surface, arrangement of heaters, viscosity of the fluid, heat transfer coefficient of the wall, and depth of the liquid were changed successively for the purpose of understanding the influence of these factors on the convection current and the temperature distribution. From the results obtained the authors pointed out some important characteristics of the convection current. Some of them are digested as follows:(1) The change of heat input causes the proportional change of temperature gradients both in vertical and horizontal directions as well as the amount of heat discharged from unit surface area of side and bottom walls, but it has not so much effect on the flow velocity of convection current.(2) Increase of heat input indicates a tendency to shift upward the circulating current and consequently the fluid near the bottom remains stagnant. These tendencies were also observed when the viscosity of fluid was decreased and when the heaters concentrated at the center of the vessel.(3) Decreases of the overall heat transfer coefficient of wall, depth of the fluid and increase of viscosity of the fluid result in a reduction in the velocity of convection current. Generally it could be pointed out that the change of the flow velocity is not so large as one would expect at first. This may be regarded as self-controlling effect of the convection current.