摘要:

Compositions in the series Na1+xZr2P3‐xSixO12and Na1+4zZr2‐zP3O12, where x = 0≤x≤1 and z=0≤z≤1/2, have thermal expansions that can be controlled (by selecting the composition) to values in the range<10×10‐7in a temperature regime of a few hundred degrees. The lowest a values were obtained for x ∼

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1984.tb19516.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Crystalline phases in the system ZrO2‐P2Oswere reexamined. Samples of varied composition were prepared by the sol‐gel route and calcining, as well as by reacting mixtures ofZrO2and NH4H2PO4, at temperatures from 200° to 1400°C. Confusion regarding compositions and structures was clarified, and the phase Zr3(PO4)4was confirmed. The latter can be written Zro.2sZr2(PO4)3and is iso‐structural withNaZr2P3O12. The role of mineralizers and the influence of zirconium salts can now be und

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1984.tb19517.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The thermal diffusivity of hot‐pressed SiC /BN composites is shown to exhibit a high degree of anisotropy with respect to the hot‐pressing direction as a result of preferred orientation of the BN phase. This effect is particularly pronounced at the higher BN contents at both room and elevated temperatu

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1984.tb19518.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Crystallization of the glassy grain‐boundary phase in a series of sialon ceramics fabricated using a range of hot‐pressing schedules increased the thermal diffusivity at room temperature by an average of ∼10%. For samples made by a given hot‐pressing schedule, the relative difference in thermal diffusivity between composites containing a glassy grain‐boundary phase and those in which this phase had crystallized decreased with increasing temperature. This behavior is attributed to enhanced phonon scattering in the crystalline grain‐bou

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1984.tb19519.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

By comparing the position of the K absorption edge of VOxto that of V metal, V2O4, and V2O5, it is concluded that the cation in VOxhas the classical valence of 2 + only for oxygen‐rich composition

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1984.tb19520.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The growth of α‐Al2O3from a planar specimen of thermally grown γ‐alumina on a molybdenum transmission electron microscope grid was studied. The α‐Al2O3grows into the transition alumina matrix and then thickens via a ledge growth mechanism. Faceted Mo crystallites cause pinning of α‐Al2O3ledges and are larger on α‐Al2O3than on the transition

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1984.tb19521.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The decrease in size dependence of thermal diffusivity measured by the laser‐flash method with increasing specimen thickness for a lithium aluminosilicate glass‐ceramic is suggested to be attributable in part to the role of the view factor in radiative heat transfer between specimen surfaces. Appropriate expressions for the effective radiative thermal conductivity and diffusivity are derived. Comparison of the observed and predicted specimen size dependence suggests that the view factor should be taken into acco

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1984.tb19522.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Fine‐grained, homogeneously dispersed alumina‐zirconia and zirconia powders were prepared by evaporative decomposition of solutions. The pure metastable tetragonal zirconia powder transformed to the monoclinic form when it was heated to 1150°C. The zirconia in the alumina‐zirconia powder, which was also in the tetragonal form, did not transform when the powder was heated to 1150° C. This result is explained in terms of inhibition of coarsening of the zirconia grains by the alumina pa

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1984.tb19523.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

A kinetic model for the removal of optical defects in glasses by exposure to hydrogen or deuterium gas is presented. Since annealing involves a chemical reaction at low temperatures, it is called “chemical annealing” to distinguish it from the common, higher‐temperature, thermal annealing processes. As an example, this model is applied to the elimination of the aluminum/oxygen hole center in irradiated vitreous silica at 73°C in 93 kPa

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1984.tb19524.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1984.tb19526.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY