ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb13792.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

The mechanical and physical properties of pyrolytic graphite are closely related to the structure produced during its deposition. It is shown how various features of the deposited structure can be predicted with some accuracy. These features include the structure of isolated nodules, the influence of various substrate conditions, and the effects of continuous nucleation. The effect of these structures on properties is discussed and the relation of the residual stress state to the deposition conditions is explained.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb13793.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

An improved counterbalanced sphere viscometer‐densitometer was used to obtain information at temperatures between 1000° and 1400°C for (a) molten B2O3, (b) a series of borosilicate melts containing up to 55 mole % SiO2, and (c) a series of borogermanate melts containing up to 65 mole % GeO2. The dependence on composition of these structure‐sensitive parameters was used to develop a model for the alteration of molten B2O8by other network‐forming species. The B/Si or B/Ge ratio is shown to be a significant factor in determining melt structure. The silicon (or germanium) atoms appear to be widely separated in the B2O2solvent for compositions in the 0 to 10‐20 mole % SiO2(or GeO2) region. The evidence suggests that a gradual microclustering of SiO2(or GeO2) accompanies moderate departures from ideality for B2O3in the 10‐20 to 60 mole % SiO2(or GeO2) region. Extensive micro‐clustering of SiO2(or GeO2), approaching network formation, appears to occur in the 60 to 100 mole % SiO2(or GeO2) region; some of the boron atoms remain in clusters and/or are forced to adopt a tetrahedral configuration i

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb13794.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

The barrier‐layer model previously proposed to explain the anomalous increase in resistivity that occurs in doped BaTiO3has been reexamined in the light of data obtained from more recent experiments. The picture thus obtained describes correctly and quantitatively the resistivity anomaly and the frequency and voltage dependence of the resistivity in the entire temperature range investigated (‐180° to +200°C). The activation energy of the donors and of the surface states as well as the density of states in BaTiO3were determined and are in close agreement with other investigations. Comments are made regarding the uncertainty of the nature of the surface s

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb13795.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

Magnetic susceptibility data between 4.2° and 300°K have been obtained for the (Al,Cr)2BeO4solid‐solution series. Chromium chrysoberyl is antiferromagnetic with a Néel temperature near 28°K; above 60°K it obeys the Curie‐Weiss law with θ= 13OK and an effective atomic moment of 3.2 Bohr magnetons. A four‐sublattice Weiss model consistent with the experimental results i

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb13796.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

Magnesium oxide crystals show a wide variety of deformation and fracture modes under tension. These modes are determined by the number of slip systems operating concurrently in a given volume. (1) At low temperatures, slip is confined to a single (110) (110) system and plasticity is limited by stress concentrations which develop where slip switches from one plane to another. (2) At intermediate temperatures, (110) (110) slip systems at 90° can interpenetrate but those at 60° cannot. Mechanical properties then depend on the initial slip distribution. When slip is confined to 90° systems there is little work hardening and crystals neck down to a knife‐edgeductile fracture.When slip is confined to 60° systems, crystals work harden and fracture by cleavage. (3) At high temperatures, dislocations can interpenetrate on all systems and polygonization can occur. After easy glide the crystals work harden and elongate over 100% before fracturing in a completely ductile manner. The transition temperature from one mode to another depends on strain

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb13797.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

An electrophoretic technique was used to determine the variation of charge on a kaolinite particle as a function of temperature. A monodies‐persed fraction of kaolinite was treated with various amounts of sodium hydroxide. The pH, conductivity, and electrophoretic mobility of the clay were determined as functions of temperature. From this information the charge on the particles and an energy related to the energy of adsorpti

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb13798.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

Phase relations in the spinel region of the system FeO‐Fe2O3‐Al2O3were determined in CO2at 1300°, 1400°, and 15000°C and for partial oxygen pressures of 4 × 10−7and 7 × 10−10atmospheres at 15OO°C. The spinel field extends continuously from Fe3O4

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb13799.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

A theory to introduce particle‐size distribution of the reacting component into Carter's equation on solid‐state reaction is described. The particle‐size distribution is defined as follows: The reacting component is divided according to particle size into groups and the mean particle sizes of each group are set in a geometrical series. By introducing the particle size distribution into the equation, the reacted fractions of the groups can be mathematically determined. The theory was applied to the solid‐state reaction of lead zircon‐ate from lead oxide and zirconium oxide having a particle size distribution. Using the measured particle‐size distribution of the zirconium oxide and the overall fraction of zirconium oxide reacted, an activation energy of about 100 kcal per mole was

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb13800.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

By streaming potential measurements, the zero point of charge (zpc) of or‐Al2O3having a fully hydroxylated surface was found to occur at pH 9.2 ± 0.2. By calcining the alumina at temperatures above 1000°C, the zpc was lowered to about pH 6.7. By aging the calcined material in water at room temperature for a period of weeks, the surface was rehydroxylated and the zpc increased. The zpc of MgO occurred at pH 12.5 f 0.5. Because of its high solubility, the zpc of MgO was not affected by heat treatm

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb13801.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY