ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1957.tb12570.x

出版商:Blackwell Publishing Ltd    

年代:1957

数据来源: WILEY

摘要:

The weight loss, dye absorption, crystalline phase or phases, dielectric constant, dissipation factor, and temperature variation of dielectric constant were determined for various bodies in the system (Ba, Ca, Pb)TiO3fired in an air atmosphere at temperatures from 800?° to 1400°C. The per cent of PbO loss is proportional toe−B/T, whereBis a constant andTis the absolute temperature. It is possible to fire most bodies in this system to zero (visual) dye absorption, but the sensitivity of the dissipation factor to moisture shows that some bodies are not well fired in the electrical sense. The electrical properties correlate well with the crystalline constitution. The two‐phase region of the barium‐calcium titanate binary extends into the ternary to about 35 mole %, lead t

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1957.tb12571.x

出版商:Blackwell Publishing Ltd    

年代:1957

数据来源: WILEY

摘要:

The amount of reacting material in a sample investigated by differential thermal analysis can be determined from the peak area according to the Boersma equation, which accounts for heat flow through sample and thermocouple wires. This relation has been checked by experiment and it has been found that the use of different thermocouples for the calibrations may lead to variations of about 30%. The values obtained for heat transfer through a sample and thermocouple have been checked by comparison of computations and observation of base‐line offset at the beginning of a run and exponential decay of the amount of heat dissipating out of a sample. It is shown that according to the equation it is not the total amount of reacting material that determines the peak area but merely the density of the material near the thermocouple. The sensitivity of the method for quantitative analysis is discussed in relation to the possible variations in the factors involved, namely, density and heat conductivity of the sample and heat transfer through the thermocoupl

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1957.tb12572.x

出版商:Blackwell Publishing Ltd    

年代:1957

数据来源: WILEY

摘要:

Systems of five or more components cannot be represented in three‐dimensional space. In working with these multicomponent systems, a method must be devised where it is not necessary to visualize the system. A general equation for a system of any number of components is presented. The derivation of the constants by the use of a unity coefficient is demonstrated for hypothetical and for actual systems. Relationships in the quinary system Na2O–Fe2O3–Al2O3–SO2–CaO are derived and the transformation equations are

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1957.tb12573.x

出版商:Blackwell Publishing Ltd    

年代:1957

数据来源: WILEY

摘要:

The ability to form a glass, i.e., the ability to form bonds which lead to a vitreous network, appears periodically in the classification chart of the elements. Thus simple glasses containing only one kind of atom are formed by the elements of Group VI of the periodic table (O, S, Se, and Te). Only these elements are known to form monatomic (primary) glasses and they retain the ability to form a vitreous network when mixed or chemically bound to each other. The elements of Group VI also form binary glasses, i.e., glasses containing two kinds of atoms, with the elements of Groups III, IV, and V. Experimental evidence of the glassforming capacities of these elements and compounds is given; about twenty new glasses suggested by the foregoing were prepared in the author's laboratory. Binary glasses are also known to exist composed of an element of Group VII (F, Cl, I, or Br) and an element of one of Groups II, III, and IV or a transition element. Experimental evidence for these glasses is presented.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1957.tb12574.x

出版商:Blackwell Publishing Ltd    

年代:1957

数据来源: WILEY

摘要:

Birefringence measurements were made on glass‐to‐metal seals with simple geometries during cooling at various rates. Thermal contraction data were also obtained on the metal and on the glass while cooling at the same rates. Using these data, the viscosity of the glass during cooling at a constant rate was calculated. The viscosity deviates markedly from the equilibrium curve and is a function of cooling rate in this temperature region. Viscous flow in the seal is measurable as much as 125°C. below the strain p

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1957.tb12575.x

出版商:Blackwell Publishing Ltd    

年代:1957

数据来源: WILEY

摘要:

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 ThO2when 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 aci

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1957.tb12576.x

出版商:Blackwell Publishing Ltd    

年代:1957

数据来源: WILEY