ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb13734.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

Although the greater portion of ground. feldspar and flint particles is in the noncolloidal range, the results of experiments conducted on commercially available flint and feldspars show conclusively that variations in the specific surface of these materials, stemming from differences in particle‐size distribution, can be a major factor in variable slip behavio

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb13735.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

A coating consisting essentially of zircon and glass was fired in vacuum on tungsten wires. Coated wires were tested up to 10 hours at 3000°F. in an air atmosphere. Microstructural and X‐ray diffraction analyses indicated that the coating on the tested specimens consisted of glass and monoclinic zirconia and that certain tungsten oxides were present in the coating. These analyses also indicated that the probable mechanism of degradation in this type of coating may be attributed to the gradual migration of oxygen through the coating, with the resultant formation of tungsten oxides which then migrate to the coating surface and volatili

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb13736.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

The internal friction of partly crystallized Li2O.‐2.75 SiO2glass fibers, containing a maximum of 78% lithium disilicate crystals, was measured by the torsion pendulum technique. The following changes in the internal friction were observed with increasing crystallization: (1) The low‐temperature peak, generally attributed to the stress‐induced diffusion of alkali ions, decreased continuously in height and shifted to higher temperatures at the higher crystal contents, (2) the intermediate‐temperature peak decreased continuously in height, and (3) a new relaxation, which first appeared as an inflection in the background of the glasses which had been nucleated at 500° C. without any crystallization, became a well‐defined peak in the partly crystallized fibers. It is suggested that this new relaxation may be an indication of the early stages of nucleation. Possible explanations are given for the high‐temperature relaxation observed in the partly crystall

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb13737.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

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 magnesiowüstite solid solution phase and liquid, under equilibrium condit

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb13738.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

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 ΔHof 11 cal. per mole. Pb3O4underwent a disproportionation reaction yielding PbO and “Pb2O3.” The equilibrium curve for this reaction was measured, and ΔHwas determined to be 4

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb13739.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

The effect of additions of 0.22, 0.44, 0.88, and 1.76% A12O3(Si4+/A13+ratio of 200:1, 100:1, 50:1, and 25:1) on the transformation of Brazilian quartz to cristobalite was studied at 1500°, 1530°, and 1570°C. The smaller percentages of A12O3(0.22 and 0.44%) catalyzed the transformation of quartz and the formation of cristobalite considerably. The rates of transformation of quartz with 0.88 and 1.76% A12O3were slower than with 0.22 or 0.44%, indicating a critical A13+/Si4+ratio where the catalytic effect was found to be maximum. This appeared to occur at about 0.5% A12O3. The transformation rate of quartz indicated that the reaction was first order. Cristobalite, however, showed two different rates; the initial rapid growth was followed by a slower rate. The point of changeover was found to be at about 30 ± 5% cristobalite. The critical nature of the A13−/Si4+ratio at about 0.01 (or A12O3/SiO2± 0.005) may have some bearing on the properties of silica refractories with more or less than 0.5%

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb13740.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

A high‐temperature microscope for use with transmitted or reflected light up to × 400 magnification and up to 1400°C. was constructed. Nucleation and crystal growth in sodium disilicate glass was studied with this microscope. Heterogeneous nucleation occurred at the interface between the glass and the platinum heating element from 450° to 870° C. with a maximum at 600° C. Heterogeneous nucleation also occurred at the glass‐atmosphere interface from 25° to 375° C. as a result of surface reactions with water vapor. No homogeneous nucleation was observed. Linear growth rates of α and β sodium disilicate crystals were measured from 600° to 870° C. in two sodium disilicate glasses. Metastable growth of both α and β was observed, and growth rates of α and β were the same at a given temperature for a given glass. An equation relating fluidity and undercooling to growt

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb13741.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

In this study 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 (X2O3)M(BaTiO3)1‐MwhereXis 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° to +330°C. An anomalous increase near the tetragonal ‐ cubic transition temperature at 120°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 exhibitedn‐type behavior whereas the cubic phase wasp‐type. The rhombohedra1 and orthorhombic phases exhibited conduction activation energies of the order of 0.2 e.v. whereas that in the tetragonal phase was appro

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb13742.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

The formation of yttrium iron garnet, Y3Fe2‐(FeO4)3, starting with (1) Fe2O3and Y2O3and (2) Fe3O4and Y2O3, was studied as a function of temperature and time by means of magnetic moment and X‐ray measurements. The reaction began at 600°C. and was completed at 1200°C. The perovskite phase appeared only between 600° and 800°C. Above 1200°C. only the garnet phase was present. The microwave line width andg‐factor at 9303 mc. per second were also measured and related to the preparation

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb13743.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY